My Memories of Van Wyngaardt

My Memories of Van Wyngaardt

To view the page listing all articles related to memories, visit “My Memories.”

On Monday, 18 March 2019 I started working at Van Wyngaardt in Johannesburg. Here are my memories of the company.

Arrival early 2019

I drove my car up from Cape Town on the weekend of 15 March 2019. I was appointed as sales manager, but the factory was in such a state that it demanded urgent and detailed attention.

Paul, the Van Wyngaardt team and I embarked on a turnaround strategy and the following received urgent attention: hygiene, food safety, recipes; SOP’s (Batch Companions); re-doing spice make-up; equipment maintenance; factory capacity; staff discipline; accounting; product costings; plant refrigeration; client base and business model; suppliers; deboning; production plans; packaging; QC program headed by a competent QC manager; aligning with the right micro laboratory; outsourcing R&D; re-evaluate the product offering; software packages and IT integration; linking sales and operations; distribution; competitive strategies and products; dispatch procedure; revamping night shift. Before we could seriously look at sales, these all had to be addressed.

It took us till the end of July 2019 before the majority of these received sufficient attention for us to shift focus to evaluate and adjust the business model in order to establish a commercially viable operation.

The first order of business was to understand the current business model. We did promotions at existing clients which helped to give us the insight we needed into the reasons why they are actually doing business with Van Wyngaardt. The current business model became clear. There was a big problem in that it did not align with the objectives of the shareholder.

In order to develop a new strategy which is in line with the hopes and dreams of the owner, for myself, I first had to find the soul of the company and the region. Nothing without a soul is ever worth pursuing.

I turned 50 on 13 April 2019 which I celebrated on Eastwick Stud Farm. By itself, this was very symbolic – indicative that something profound is developing. I came from the Western Cape – an area replete with soul and substance. Johannesburg is notoriously soulless and devoid of substance. Why was I here? How did this happen? Previous business partners stole and destroyed the soul of my previous project, Woodys Brands. They killed it! Why did the universe bring me here to Johannesburg?

Glimpses of the answer came to me on the day I turned 50. My introduction to Van Wyngaardt was very rough. A shock to the system, to state it mildly.

Etienne gave me an introduction to his Nguni cattle; I climbed to the top of the Magaliesberg mountains; I discovered old ruins. When this occurred, I took notice. Slowly but surely I started seeing a vision. Nguni cattle showed me their soul and introduced me to the ancient inhabitants who took me in and my eyes were renewed. The haze of the violence done to Woodys by my previous partners lifted and I started seeing clearly. I fell in love with the concept of this company, Van Wyngaardt.


In my heart has always been one certainty: together with colleagues and loved ones we will achieve the impossible! Paul and I headed the turn-around team. Carlo joined us from Cape Town as production manager. Jaques was appointed to head Food Safety and QC. Johann continued to ensure that staffing is done correctly; Hennie took over electrical work; Jonothan made dispatch his own. Julian’s staff from Johannesburg took over the refrigeration plant with Lu as the point man. Slowly but surely a new model started taking shape in our collective mind. Tristan, Minette, and Lauren continued to be instrumental in motivation and encouragement.


A new concept was first suggested by Frank from Castlemain; a year later precipitated by Haresh Keswani and Etienne Lotter. Concepts that started in Cheviot and Gorde Bay in New Zealand around Manuka huney now distilled. Etienne and Christo continued preaching a very focussed vision. I hiked the ancient ruins while my family remained pivotal. The Van Wyngaardt vision started turned into reality. Cherise, Nicole, Jocelyn – they all became custodians of the future of something remarkable! Carlo with Stephen by his side continued to improve on the basics of our growth and transformation, the factory itself.

Back at the factory key aspects of running a meat plan were addressed. We were all given heart and soul to the project! After one deep clean I landed up in the emergency unit with severe breathing difficulty. Some colleagues left us but even more importantly was the ones who joined us. The team grew in its ability. Dr. Francois Mellett re did all our functional ingredients and continue to work closely with the team.

A New Concept

Product quality took a major step forward. This was another foundation of a new strategy. In August 2019 a new way of marketing the range was launched. A conduit for high-quality German, Spanish, Italian, Danish, Dutch, Belgium, and English cured and fermented products. The quest for its African soul continued. The goal was and is nothing less than to create something authentic which will celebrate the great culinary heritage of our land.

Years of research started bearing fruit. There emerged evidence of a great heritage of smoked, fermented and cured meat, born from the African soil. Dr. Henry Lichtenstein describes a scene in his book, “Travels in Southern Africa” that conjures up the heart of Van Wyngaardt.  He writes that when their party traveling through South Africa approached the Winterhoek Mountains in the Cape, they met an old German who once worked for the East Indian Company and who is a veteran of the Esterhazy’s regiment.  For the greater part of the year (he) saw no Europeans, lived among his African friends and sustained himself almost entirely on dried mutton and biltong.” The Guardian (London, England), 21 July 1952, page, from the article, “Biltong for the Arctic.”

I imagine his surname to have been Van Wyngaardt. He knew how to prepare the best German cured and fermented dishes but was clearly influenced by African tradition. By drying the strips of meat, he created biltong which is an African dish, influenced by North European practices of adding vinegar to their hams.

This is the heart of the spirit of Van Wyndaardt!  It takes the best from Europe and fuses it with homegrown African dishes and curing methods. The influence comes from all the people and tribes of this land. From Boer to Brit, German to Italian and Spanish. From Tswana, Sotho, Venda, Swazi, Xhosa, and Zulu. From the Khoi to the San Bushman.

Just after we launched the revamped concept in Jasmyn, Lauren joined me in Johannesburg to lend a hand in rolling out the new strategy. It was in its infancy and we needed to think on our feet.

Paul crunch the numbers and kept us all focused on the bottom line. A master of good practices, he diligently patrolled the fences and worked on the strategy.

The ancient voices spoke to me from the technology they embraced, the cities they built, the lands they walked and the food they prepared. I am not sure where any of this will end, but I am convinced that the universe has uniquely gifted and prepared the group of people, assembled for the task to give the manifestation of a grand vision.

The story continues!

(c) Eben van Tonder

MDM – Not all are created equal!

MDM – Not all are created equal!
By Eben van Tonder
16 April 2018



Last Saturday I turned 50.  I did three things that I insanely enjoy.  One was to spend time with a meat and business legend.  Over the years I have researched and got to know many such men.  Those who are still alive, I got to know personally.  Those who passed away, I studied their lives.  Jacobus Combrink who created arguably the most successful butchery in South Africa in the 1800s;  David de Villiers Graaff, his protege and the man who took Combrink & Co. and turned it into the Imperial Cold Storage and Supply Company Ltd. (ICS) which in turn merged into the food conglomerate Tiger Brands with the Combrink & Co part of the operation being assimilated into the Enterprise/ Renown merger;  JW Moore who set up the Eskort curing operation under his Farmers Cooperative Bacon Curing Company in Estcourt, Natal.  Further afield there is the three Harris’s.  Nick Harris, whom I have the privilege to know, was key in the creation of the New Zealand curing operation, Hellers.  Together with his brother, Bryan, they currently own an abattoir, deboning and processing plant in Cheviot where they grow up and where Nick owns large farmland.  From the previous century, the brothers George and Thomas Harris from Calne in Wiltshire who created C & T Harris, arguably the most successful bacon operation in British history.  From Australia, Wright Harris and his Castlemaine Bacon Company who fought in the second Anglo-Boer war in South Africa.  Interestingly enough, none of the Harris’s from New Zealand, Australia or England are related.  From the USA there is the legendary Philip Armour and his Armour Packing Plant in Chicago who was, according to my research, closely linked with the direct addition of nitrites in curing brines. His company is one of the reasons why anti-trust laws exist in the USA.  For my 50th birthday, I was on the farm of Etienne Lotter.

Etienne stands shoulder to shoulder with any one of these formidable men. It fascinates me that all these men share an unwavering focus, the ability to make quick and good decisions, resolve of steel, passion, commitment, and an obsession to invest in people.  A story is told of Phil Armour that he showed his packing plant to visitors one Sunday.  Ford got his idea about assembly lines from Phil and it was indeed something to behold.  A newspaper reporter tells the story that they were walking back from the factory and could see the church where many of the men who worked for him attended adult education after church.  He reportedly pointed to his packing plant and said, “there we make bacon” and then to the church and said, “and there we make men!” He liberally invested in people and he himself claimed that he never fired someone.  That is not to say that it was easy to work for him as is or was true of all these men.

The second thing I did which I insanely love was to hike up the Magaliesburg on Etienne’s farm, Eswitch Stud Farm.  There was no clear footpath up and it made for an adventure through the thick grass, trees, and ferns.



The 3rd thing was talking meat curing with Etienne the entire Saturday and Sunday morning!  The experience was volcanic with its seismic aftershocks still reverberating through my psyche!  I’ve been in the meat industry no for 14 years.  Till my day with Etienne, I thought of MDM (Mechanically Deboned Meat) as something like flour or sugar, a commodity of uniform characteristics and quality.  Was I wrong!  It turns out that as is the case with all ingredient, functionality follows processing techniques.  Inspired by Etienne’s passion for MDM, I started to investigate  What a world started opening up!  I share some of my initial discoveries.


“Mechanically deboned meat (MDM), mechanically recovered meat (MRM) or mechanically separated meat (MSM) are synonyms used to mark the material, obtained by application of mechanical force (pressure and/ or shear) to animal bones (sheep, goat, pork, beef) or poultry carcasses (chicken, duck, turkey) from which the bulk of meat has been manually removed” (Hui, 2012)

There are a number of different methods to achieve this, but most of them result in cell breakage, protein denaturation, generally an increase in lipids and haeme groups and poorer mechanical properties.  (Hui, 2012)

MDM is mainly used in producing emulsion-type products such as Vienna’s, Russians, and Polony (in South Africa).  “Meat recovered from bones or carcass parts by mechanical procedures is generally considered to be of poor nutritional and microbiological quality”  (Hui, 2012)  In many parts of the world, strict legislation governs the use of these products.  When compared to the rest of the world, South Africa lags behind in this regard.  There are certain producers who choose to only use muscle meat in the production of its emulsion sausages, loaves, and hams, and the consumer is entirely left to study ingredients declarations to determine if MDM is present or not.  There are also a number of different qualities of MDM and it is by no means correct to claim that all MDM are of poor microbiological quality and share the same low nutritional characteristics.  The different production methods of MDM can broadly be separated into hard and soft MDM.

Hard MDM

Hard MDM is made from pork or beef where it will be hard to clear the bones from all the small meat bits.  It can be made from chicken also.  When the valuable pieces of chicken and turkey (wings, breasts, and legs) are removed, hard MDM is made from the carcass that is left.  In this method, the bones or carcass is placed in some kind of a pressure chamber with small holes in it and the bones or carcasses are subjected to high pressure which removes the skin, meat bits, connective tissue, etc. still stuck to the bones.  These pass through the small holes of the barrel sieve (around 0.5 – 0.8mm in diameter).  The basic principle remains the same across many different machines namely that high pressure is used to clean the bones.  (Feiner, 2006)

Hard MDM should not contain bone bits larger than the hole size of the sieve, but in reality, on account of the enormous pressure used to remove the fragments from the bones, they often do.  The consequences of the presence of bone pieces in the MDM elevates the calcium and phosphorus content in hards MDM quite high.  These, in turn, interferes with the functionality of phosphates in emulsion sausages.  (Feiner, 2006)

The micro status of hard MDM is of great importance.  The reason for the high micro in this MDM is the large surface area of the meat.  The levels should not be higher than normal minced meat.  As always, processing conditions play the key role here and low micro levels are never guaranteed. (Feiner, 2006)

Another problematic feature of hard MDM is the presence of bone marrow, particularly in chicken MDM.  This speeds up the oxidation of fat since bone marrow contains a fair amount of metals such as iron, magnesium, and copper “which acts in a pro-oxidative manner.” (Feiner, 2006)

The fat content of hard MDM is inconsistent.  Protein, fat and bacterial levels should be part of MDM specifications.  The shelf life of pork and chicken MDM is much shorter than beef MDM in both chilled and frozen state.  The reason is the fatty acids in pork and chicken have high levels of unsaturated fatty acids in the fat fractions when compared with beef.  “Rancidity develops quickly within such material.”  (Feiner, 2006)

MDM has a  pasty texture. Due to the meat recovery method, there is a high proportion of “pulverised muscle fiber residue.”  There is also a large proportion of “partly destructured muscle fibers.”  We call such change in muscle fiber ‘‘destructuration” (Sifre and others 2009)”  (Feiner, 2006)

Soft MDM

Soft MDM, on the other hand, is produced from meat trimmings, high in connective tissues.  The process avoids the enormous pressure of the hard MDM methods by the action of a roller on the meat.  In this system, the material is put through a machine that separates the meat from connective tissues, cartridge, etc. based on the different hardness of these components.  The process is much more productive in terms of time and input required when compared to the hard MDM methods.  In many instances, a “Baader” machine is used or something similar. (Feiner, 2006)

A very typical production method is as follows.

  1.  Grind minced meat through 13 – 20mm mincer plate;
  2.  Feed through Baader machine
  3. The Baader machine has small holes in a rotating drum and the meat passes under the drum so that the drum presses on the meat.  The soft lean meat, due to its texture, passes through the holes in the rotating drum and is collected there and fed out on the side of the machine;
  4. The harder connective tissue, bone fragments, etc. are ejected at the front of the machine, having been unable to be pass to the inside of the drum where only soft lean meat is collected. (Feiner, 2006)

Both the collected connective tissues, sinews, etc and the soft MDM from inside the drum has enormous functional applications and products are made from both.

Comparing hard MDM and soft MDM, the following functional differences emerge:

Soft MDM Hard MDM
Protein Content:  15% – 17% Protein Content:  12% to 15%
Of this, 70% to 80% is equal to protein found in muscle meat. Of this, 60% to 70% is equal to the protein found in muscle meat.
Consequently: Consequently:
– Much improved WBC (Water Binding Capacity); – Reduced ability to immobilise water
– Much improved ability to emulsify fat – Reduced ability to immobilise emulsify fat
70% to 80% WBC and emulsifying characteristics of lean muscle meat
All protein in soft MDM still functional Reason is: denaturing of proteins and cell breakage during processing.
Fine and mushy consistency
– Do not support firmness in final product
pH: between 6.2 and 6.4
– poor colour developmenty
– MDM only products exhibit a darker colour.


Examples of legislation in place in many parts of the world related to MDM are the following:

Bones to be used in the production of Hard MDM must be stored at between 0 and 2 degrees C no longer than 24 hours or be frozen for a maximum of 8 days before it is processed.  If it is frozen, this must take place immediately after production.  The chilled bones must be utilized within 24 hours.

Besides these, fat percentages, minimum requirements on nutritional value, and percentage connective tissue are set in many countries.

Functional Characteristics

Despite the fact that many different MDM producers achieve these values, there exists an enormous range of varying functional characteristics of MDM, produced by different manufacturers, on account of different process and machines employed in its production.

Lets first evaluate meat that was recovered through deboning with meat processed with an MDM machine. Froning (1970) for example compared hard deboned white and dark chicken meat with chicken backs and necks and turkey frames processed with a Paoli machine and chicken backs processed with a Beehive deboner for emulsification properties. (McMillan, 1980)

He found that MDM was most stable in a bowl cutter to temperatures of 7.2 to 12.8 deg C. Above 12.8 deg C, the tensile strengths of finished emulsions decreased and the amounts of fat and gel-water released during processing increased. By comparison, the hand boned broiler meat was stable at all chopping temperatures.  (McMillan, 1980)

He further found that MDM had less protein matrix available for emulsion than hand-deboned meat, “due to greater collagen dispersion and possible loss of protein solubility caused by deboner protein denaturation.”  (McMillan, 1980)

The tests may have been conducted in the 1970s and 1980s, but the principals are equally valid.  Froning  et al. (1971) used 15% turkey MDM in red meat frankfurters to study its stability and acceptability. The MDM was produced with a Paoli deboning machine and the results indicated a higher capacity to emulsify oil per 2.5g sample than pork trimmings, but a reduced capacity than boneless cow meat.  (McMillan, 1980)

Turkey MDM  had a reduced WHC compared to red meat sources.  Gel-water loss was greater in frankfurters made with 15 percent turkey MDM.  Their research alluded me to another very important consideration in the functionality of MDM.  In SA, all MDM is sold frozen, but in other countries, MDM is customarily produced, sold and used unfrozen.  Froning  et al. found that frankfurters which fresh MDTM had less cook
than franks containing MDTM which was stored frozen for seven days prior to use.  (McMillan, 1980)

In terms of taste, no major differences were found between control frankfurters, frankfurters containing previously frozen turkey MDM and fresh MDM in terms of taste and colour.  The superiority of pure meat over MDM was confirmed by Schnell et al (1973).  They compared poultry MDM with hand boned carcass meat.  The texture frankfurters produced with hand-deboned meat was firmer than those produced with MDM. (McMillan, 1980)

Another interesting study, confirm the differences between different MDM producers was done by Baker et al. (1974).  They compared poultry MDM from three machines to measure the effect of chopping time on taste panel evaluation and frankfurter stability. “Chopping time had little effect on results of these tests, but source of the MDPM caused differences in frankfurter yield, stability during cooking, emulsion viscosity, and taste panel scores of texture and juiciness. More dense poultry MDM and smaller, more evenly distributed fat globules contributed to the stability of frankfurters with two of the poultry MDM sources as compared to the third MDPM source (Angel et al., 1974).  (McMillan, 1980)

Some researchers have reported that they were able to “manage” negative characteristics in certain MDM typed through various techniques such as controlling and altering the pH, but if this can be duplicated in a factory environment if questionable.

Foodnavigator reported in 2018 on a project in the EU seeking to test MDM in terms of the structural integrity as a key indicator for its quality. The software reportedly use image processing algorithms to quantify degrees of degradation in meat. The aim is to test cheap imports into the EU which claims comparability with high quality EU MDM.

In the EU, certain producers such as Polskamp Meat Industrie in Holland is able to produce MDM of exact specifications. Processors can choose fat content of ±11%, ±12%, ±14% and ±16% and protein content of between ±15% to ±18% The colour of their chicken MDM is consistent being the typical colour of fresh chicken meat of pink-red. This sets them apart from many producers who is unable to certify such exact parameters, again confirming our thesis that not all MDM are created equal!

Polskamp is a good example of using technology to overcome the inherent problems in hard MDM. They pioneered low pressure technology to remove meat from bones, thereby avoiding the negative aspects associated with high pressure meat separation.

They claim that their 3 millimeter meat is “produced using special machines that can separate meat from the bone. Contrary to mechanically separated meat, 3 millimeter meat is produced using low-pressure technology that better preserves the structure of the chicken meat. 3 Millimeter meat is also characterised by its lower calcium content and lighter colour. Polskamp Meat Industrie offers its buyers several types of 3 millimeter meat, e.g. a white product and a rose-coloured product.” (


These and more recent studies indicate the need for the processor to conduct a thorough evaluation of its MDM source.  At the end of the day, all these studies point to the fact that the different MDM’s on the market, produced by various manufacturers, using a range of different source material’s are not all created equal.

By choosing the right MDM source, it may be possible to omit binding and water absorption material such as the different soya products or starches.  The effect of freezing and freezing time on MDM is another key aspect to be evaluated and along with aspects such as fat %, connective tissue%, and water content must command our careful attention.

Finally, careful attention should be given to the different methods to extend the shelf life of MDM by reducing lipid peroxidation and of microbial growth.

Even if pure meat products is our objective, the lessons found in the production of MDM and the subtle techniques of optimizing yield, profitability while achieving exceptional product quality will benefit us tremendously if we master it!

Further Reading

The nutritional and physical characteristics of mechanically proc

Hui, Y. H. (Editor) 2012. Handbook of Meat and Meat Processing. CRC Press.

Hiking photos

It is not every day that one turns 50.  Here are the rest of the photos from my hike up the Magaliesberg on 13 April 2019.

Hiking Photos – 50th birthday


Feiner, G.  2006.  Meat Products Handbook: Practical Science and Technology.  Woodhead Publishing.

Hui, Y. H. (Ed.) 2012.  Handbook of Meat and Meat Processing. Chapter: Mechanical Deboning.  CRC Press; Taylor & Francis Inc.

McMillan, K. W..  1980.  The nutritional and physical characteristics of mechanically processed beef and pork product.  Iowa State University.  Retrospective Theses and Dissertations. 7342.

Photo Credit:

Continental Franks:

All other photos by Eben

Soya: Review of some health concerns and applications in the meat industry


Vagadia et al. (2015) state that soya “contains a variety of bioactive anti-nutritional compounds including protease trypsin inhibitors, phytic acid, and isoflavones that exhibit undesirable physiological effects and impede their nutritional quality. Inactivation of these trypsin inhibitors, along with deleterious enzymes, microbes, bioactive components and increasing the protein quality by improving its texture, colour, flavour, functionality and digestibility are the most important factors to be considered in the crucial stage in the manufacturing of soy products.”  Are there reasons to be concerned and what can we learn about its history and possible applications in the meat industry?

Historically Valued Plant

Before we break down the concerns raised by Vagadia et al. (2015), it is instructive to know that soya has been consumed in many countries since before recorded history.  A rich tradition developed around its use in medicine from antiquity.    Duke (1991) showed that a search of his “Medicinal Plants of the World” database (Sept. 1981) indicated that soybeans are or have been used medicinally in China to treat the following symptoms/diseases or for the following medicinal properties (listed alphabetically; Most information from: Li Shih-Chen. 1973. Chinese Medicinal Herbs. San Francisco: Georgetown Press):

“Abortion, ague, alcoholism, anodyne, antidote for aconite or centipede or croton, antivinous, anus, apertif, ascites, ataxia, blindness, bone, bugbite, burn, carminative, chestcold, chill, circulation, cold, complexion, decongestant, diaphoretic, diuretic, dogbite, dysentery, dyspnea, eczema, edema, enuresis, feet, fever, halitosis, headache, hematuria, impotence, intoxication, kidney, labor, laxative, leprosy, malaria, marasmus, marrow, melancholy, metrorrhagia, nausea, nervine, ophthalmia, pile, pregnancy, preventive (abortion) puerperium, refrigerant, resolvent, rheumatism, scald, sedative, skin, smallpox, snakebite, sore, splenitis, splinter, stomach, tinea, venereal, vertigo, vision.”

Uses in other parts of the world include cancer, and cyanogenetic, shampoo (USA), diabetes (Turkey), soap (Asia), stomach problems (India).

Not only was it recognized as a superfood in many parts of the world, but it was celebrated for its medicinal value.  Looking at the factors of concern raised by many, we begin by looking at the most well-known concern factor of its role as a trypsin inhibitor.

Trypsin Inhibitors

The German physiologist Wilhelm Kühne (1837-1900) discovered trypsin in 1876. It is an enzyme that cleaves peptide bonds in proteins (serine protease) and is therefore essential in digestion.   It is found in the digestive system of many vertebrates, where it hydrolyzes proteins. (Kühne, 1877)  Trypsin is formed in the small intestine when its proenzyme form, the trypsinogen, produced by the pancreas, is activated. (Engelking, 2015)  A trypsin inhibitor (TI) is then something (a protein) that reduces the biological activity of trypsin and as such have a negative effect on nutrition by impairing the digestion of food.

The concern about soya’s trypsin inhibitors is of no real concern to us.  It turns out that trypsin in humans is more resistant to inhibition than is the trypsin of other mammalian species. “The effect on human trypsin of soybean trypsin inhibition in soy protein does not appear to be a potential hazard to man. Therefore, the elimination of STI does not seem to be necessary for humans.”  (Flavin DF, 1982)

“In animal diets, however, pancreatic toxicity must be considered whenever soybean protein is utilized. Soybeans should be treated to increase their nutritional benefits and decrease any animal health risks. This will ensure healthy control subjects in laboratory situations and avoid misinterpretation of pathologic data.

The treatment suggested is heat since heat will destroy most of the soybean trypsin inhibitors. Additional supplementation is required following heat treatment for amino acids such as methionine, valine, and threonine; for choline; and for the minerals zinc and calcium.  Excessive heat must be avoided since it will decrease the nutritional value of soybean protein and increase lysinoalanine, a nephrotoxic substance.

Finally, the use of STI as a promotor in the study of potential pancreatic carcinogens may prove beneficial for cancer research and might be considered in the future.” (Flavin DF, 1982)

Phytic acid

Phytic acid also is suspect due to its inhibitory effect related to nutrition.  Anderson (2018) states “It is a unique natural substance found in plant seeds. It has received considerable attention due to its effects on mineral absorption. Phytic acid impairs the absorption of iron, zinc, and calcium and may promote mineral deficiencies”  (Arnarson, 2018)

As is the case with the trypsin inhibition, the story is a bit more complicated than that because phytic acid also has a number of health benefits.

Anderson writes that “phytic acid, or phytate, is found in plant seeds. It serves as the main storage form of phosphorus in the seeds. When seeds sprout, phytate is degraded and the phosphorus released to be used by the young plant. Phytic acid is also known as inositol hexaphosphate, or IP6. It’s often used commercially as a preservative due to its antioxidant properties.

Phytic acid is only found in plant-derived foods. All edible seeds, grains, legumes and nuts contain it in varying quantities, and small amounts are also found in roots and tubers. The following table shows the amount contained in a few high-phytate foods, as a percentage of dry weight:

Phytic Acid in food

As you can see, the phytic acid content is highly variable. For example, the amount contained in almonds can vary up to 20-fold.

Phytic acid impairs absorption of iron and zinc, and to a lesser extent calcium.  This applies to a single meal, not overall nutrient absorption throughout the day.  In other words, phytic acid reduces mineral absorption during the meal but doesn’t have any effect on subsequent meals.  For example, snacking on nuts between meals could reduce the amount of iron, zinc and calcium you absorb from these nuts but not from the meal you eat a few hours later.

However, when you eat high-phytate foods with most of your meals, mineral deficiencies may develop over time.  This is rarely a concern for those who follow well-balanced diets but may be a significant problem during periods of malnutrition and in developing countries where the main food source is grains or legumes.

Avoiding all foods that contain phytic acid is a bad idea because many of them are healthy and nutritious.  Also, in many developing countries, food is scarce and people need to rely on grains and legumes as their main dietary staples.

Phytic acid is a good example of a nutrient that is both good and bad, depending on the circumstances.  For most people, it’s a healthy plant compound. Not only is phytic acid an antioxidant, but it may also be protective against kidney stones and cancer.  Scientists have even suggested that phytic acid may be part of the reason why whole grains have been linked with a reduced risk of colon cancer.

Phytic acid is not a health concern for those who follow a balanced diet.  However, those at risk of an iron or zinc deficiency should diversify their diets and not include high-phytate foods in all meals.  This may be especially important for those with an iron deficiency, as well as vegetarians and vegans.

There are two types of iron in foods: heme iron and non-heme iron.  Heme-iron is found in animal foods, such as meat, whereas non-heme iron comes from plants.

Non-heme iron from plant-derived foods is poorly absorbed, while the absorption of heme-iron is efficient. Non-heme iron is also highly affected by phytic acid, whereas heme-iron is not.  In addition, zinc is well absorbed from meat, even in the presence of phytic acid.

Therefore, mineral deficiencies caused by phytic acid are rarely a concern among meat-eaters.  However, phytic acid can be a significant problem when diets are largely composed of high-phytate foods while at the same time low in meat or other animal-derived products.  This is of particular concern in many developing nations where whole grain cereals and legumes are a large part of the diet.”  (Arnarson, 2018)


Isoflavones are a class of phytoestrogens — plant-derived compounds with estrogenic activity. Soybeans and soy products are the richest sources of isoflavones in the human diet.  (

“Since many breast cancers need estrogen to grow, it would stand to reason that soy could increase breast cancer risk. However, this isn’t the case in most studies.

In a review of 35 studies on soy isoflavone intake and breast cancer incidence, higher soy intake reduced breast cancer risk in both pre- and postmenopausal Asian women.  For women in Western countries, one study showed soy intake had no effect on the risk of developing breast cancer.

This difference may be due to the different types of soy eaten in the Asian compared to the Western diet. Soy is typically consumed whole or fermented in Asian diets, whereas in Western countries, soy is mostly processed or in supplement form.

In an animal study, rats fed fermented soy milk were 20% less likely to develop breast cancer than rats not receiving this type of food. Rats fed soy isoflavones were 10–13% less likely to develop breast cancer.  Therefore, fermented soy may have a more protective effect against breast cancer compared to soy supplements.  Additionally, soy has been linked to a longer lifespan after breast cancer diagnosis.

In a review of five long-term studies, women who ate soy after diagnosis were 21% less likely to have a recurrence of cancer and 15% less likely to die than women who avoided soy.”  (Groves, 2018)

From the above notes, it may appear that it is perfectly safe for humans to consume raw soya.  There is however one very good reason to cook soya well before it is consumed.

Lectin Effects

“Soybeans contain lectins, glycoproteins that bind to carbohydrates in cells. This can damage the cells or lead to cell death in the gastrointestinal tract. Lectins may bind to the intestinal walls, damaging the cells and affecting nutrient absorption as well as causing short-term gastrointestinal side effects. Unlike most proteins, lectins aren’t broken down by enzymes in the intestine, so the body can’t use them. Lectins can affect the normal balance of bacteria in the intestine and the immune system in the digestive tract.” (Perkins, 2018)

Dr. Mark Messina discussed the issue with Lectin in soya in a brilliant article entitled “Is Soybean Lectin an Issue?”  He writes, “Given all the attention they’re receiving, you might think these proteins are newly discovered, perhaps because of a sudden advance in technology. Given all the concerns being raised about them, you might be thinking of avoiding foods that contain them. If you do, you can pretty much say goodbye to a long list of healthy foods such as legumes (including soy and peanuts), eggplant, peppers, potatoes, tomatoes, and avocados. Despite the hoopla, studies show there is little reason for concern.

Lectins are anything but new to the scientific community. They are a class of protein that occurs widely in nature and have been known to exist in plants for more than a century. Much of the lectin research has focused on legume lectins but these carbohydrate-binding proteins are widely distributed throughout the plant kingdom. The lectin in soybeans was discovered in the 1950s.

In plants, lectins appear to function as nitrogen storage compounds, but also have a defensive role, protecting the plant against pests and predators. They are capable of specific recognition of and binding to carbohydrate ligands. The term lectin (legere = Latin verb for to select) was coined by Boyd circa 1950 to emphasize the ability of some hemagglutinins (lectins) to discriminate blood cells within the ABO blood group system.5-The term lectin is preferred over that of hemagglutinin and is broadly employed to denote “all plant proteins possessing at least one non-catalytic domain, which binds reversibly to a specific mono- or oligosaccharide.”

Orally ingested plant lectins remaining at least partially undigested in the gut may bind to a wide variety of cell membranes and glycoconjugates of the intestinal and colonic mucosa leading to various deleterious effects on the mucosa itself as well as on the intestinal bacterial flora and other inner organs. The severity of these adverse effects may depend upon the gut region to which the lectin binds. Several cases of lectin poisoning due to the consumption of raw or improperly processed kidney beans have been reported.

The lectin content of soybeans varies considerably among varieties, as much as fivefold. However, from a nutritional perspective, it is the amount in properly processed soyfoods that is most relevant. Although there has been a lot of debate about whether even active soybean lectin is harmful,  a true pioneer in this field, Irvin E. Liener, concluded that soybean lectin isn’t a concern because it is readily inactivated by pepsin and the hydrolases of the brush border membrane of the intestine. But, others think soybean lectin does survive passage through the small intestine.

Not surprisingly, autoclaving legumes including soybeans completely inactivates lectins. However, foods aren’t typically autoclaved. The most practical, effective, and commonly used method to abolish lectin activity is aqueous heat treatment. Under conditions where the seeds are first fully soaked in water and then heated in water at or close to 100°C, the lectin activity in fully hydrated soybeans, kidney beans, faba beans, and lupin seeds is completely eliminated.  Thompson et al. noted that cooking beans to the point where they might be considered edible are more than sufficient to destroy virtually all of the hemagglutinating activity of lectins. More recently, Shi and colleagues23 found that soaking and cooking soybeans destroyed more than 99.6% of the lectin content, which agrees with earlier work by Paredes-Lopez and Harry.

Finally, evidence from clinical trials in no way suggests that the possible residual lectin content of soyfoods is a cause for concern. Adverse effects typically associated with lectin toxicity don’t show up in the hundreds of clinical trials involving a range of soy products that have been published. Not surprisingly, the U.S. Food and Drug Administration recently concluded that soy protein is safe.”  (Messina, 2018)

Saponins in Soybeans

Saponins in soya are responsible for the bitter taste, foam-forming, and activities that rupture or destroy red blood cells.  Its presence in soya is probably an evolutionary development to protect it against, for example, Callosobruchus chinensis L., a common species of beetle.  Its protecting properties can be seen for example by the fact that [certain strains of] the first instar larvae, after burrowing beneath the seed coat, subsequently die without moulting. (Applebaum, 1965)

There are five known soya saponins: Soya sapogenols A, B, C, D, and E.  Saponins cannot be inactivated by cooking because cooking doesn’t break down this toxin like it does lectins.”  (Perkins, 2018)  “Triterpenoid saponins in the mature soybean are divided into two groups; group A soy saponins have undesirable astringent taste, and group B soy saponins have health-promoting properties. Group A soy saponins are found only in soybean hypocotyls, while group B soy saponins are widely distributed in legume seeds in both hypocotyls (germ) and cotyledons. Saponin concentrations in soybean seed are ranged from 0.5 to 6.5%.”  (Hassan, 2013)

Bondi and Birk (1966) investigated soybean saponins as related to the processing of petroleum etherextracted meal for feed and to the preparation of soy foods.  They found that “soybean saponins are harmless when ingested by chicks, rats and mice even in a roughly threefold concentration of that in a 50% soybean meal supplemented diet.” They are decomposed by the caecal microflora of these 3 species. Their non-specific inhibition of certain digestive enzymes and cholinesterase is counteracted by proteins which are present in any natural environment of these saponins. The haemolytic activity of soybean saponins on red blood cells is fully inhibited by plasma and its constituents –
which naturally accompany red cells in blood. Soybean saponins and sapogenins are not absorbed into the blood-stream (Note: Or perhaps not observed in the bloodstream). It may, therefore, be concluded that haemolysis – one of the most significant in vitro [in glass/test tubes] properties of soybean saponins and others–bears no ‘obligation’ for
detrimental activity in vivo [in living organisms].”  (Bondi, et al, 1966)

Birk, et al, 1980, found that “saponins are glycosides that occur in a wide variety of plants. They are generally characterized by their bitter taste, foaming in aqueous solutions, and their ability to hemolyze [break down] red blood cells. The saponins are
highly toxic to cold-blooded animals, their toxicity being related to their activity in lowering surface tension. They are commonly isolated by extraction of the plant material with hot water or ethanol.”  (Birk, 1980)  Leaching the saponins out of the soybeans, removing the bitter taste.  (Perkins, 2018)

Applications and History

Reviewing the history of the development of soya industry in Israel, brought up some interesting perspective on its application in food.

“Hayes Ashdod was one of Israel’s first company to make foods from soybeans and Israel’s first manufacturer of modern soy protein products. In 1963 the company launched its first product, a soy protein concentrate named Haypro. This product was also the first commercial soy protein concentrate manufactured outside the United States. The main applications for Haypro were as a meat extender.”  (Chajuss, 2005)

“In 1966 Hayes Ashdod Ltd. introduced texturized soya protein concentrates under the brand names Hayprotex and Contex. Hayprotex was designed for use mainly as a minced
meat extender, while Contex was designed mainly for vegetarian analogs.”  (Chajuss, 2005)

“Concerning early textured soy protein concentrates: Hayes Ashdod introduced Hayprotex and Contex in 1966, and a company we are well familiar with for making nitrite curing of meat commercially available around the world through their legendary Prague Powder, the Griffith Laboratories from Chicago introduced GL-219 and GL-9921 in 1974, and Central Soya introduced Response in 1975.”  (Chajuss, 2005)

“In 1969 Hayes started to produce Primepro, a more functional and soluble soy protein concentrate, by further treatment of the aqueous alcohol extracted soy protein concentrate (Haypro), for use as substitutes for soy protein isolates and for caseinates in various food systems, especially in the meat processing industries.”  (Chajuss, 2005)

Further reading

A tremendous resource on research on soya is HISTORY OF SOYBEANS AND SOYFOODS IN THE MIDDLE EAST


Soya is a tremendous food and protein source.  The health concerns are addressed at the manufacturing stage.  Application of isolates, concentrates and TVP are multiple.  Even today, after being available on the market for so many years, all its various applications in foods have not been exhausted.  We are limited only by our imagination and interesting work remains to integrate its use into modern meat processing plants.


Applebaum, S.W.; Gestetner, B.; Birk, Y. 1965.  Physiological aspects of host specificity in the Bruchidae–IV.  Developmental incompatibility of soybeans for Callosobruchus. J. of Insect Physiology 11(5):611-16. May.

Arnarson, A.  2018. Phytic Acid 101: Everything You Need to Know.

Birk, Yehudith; Peri, Irena. 1980. Saponins. In: I.E. Liener, ed. 1980. Toxic Constituents of Plant Foodstuffs. 2nd ed. New York: Academic Press. xiv + 502 p. See p. 161-182. Chap. 6.

Bondi, A.; Birk, A. 1966. Investigation of soybean saponins as related to the processing of petroleum ether-extracted meal for feed and to the preparation of soy foods, to provide information basic to improving the nutritional value of soybean protein products. Rehovot, Israel: Hebrew University. 80 + xvii p. USDA P.L. 480. Project no. UR-A10-(40)-18. Grant no. FG-IS-112. Report period 1 March 1961 to 28 Feb. 1966. Undated. 28 cm.

Chajuss, D.. 2005. Brief biography and history of his work with soy in the USA and Israel. Part II (Interview). SoyaScan Notes. Feb. 19. Followed by numerous e-mails. Conducted by William Shurtleff of Soyfoods Center.

Duke, J. A. 1991. Research on biologically active phytochemicals in soybeans (Interview). SoyaScan Notes. Oct. Conducted by William Shurtleff of Soyfoods Center.

Engelking, Larry R. (2015-01-01). Textbook of Veterinary Physiological Chemistry (Third Edition). Boston: Academic Press. pp. 39–44. ISBN 9780123919090.

Flavin DF. The effects of soybean trypsin inhibitors on the pancreas of animals and man: a review. Review article. Vet Hum Toxicol. 1982. 1982 Feb;24(1):25-8.

Groves, M..  2018.  Is Soy Good or Bad for Your Health?

Hassan, S. M..  2013.  Soybean, Nutrition, and Health.  Intech

Kühne, W. 1877. “Über das Trypsin (Enzym des Pankreas)”, Verhandlungen des naturhistorisch-medicinischen Vereins zu Heidelberg, new series, vol. 1, no. 3, pages 194-198

Messina, M.  2018.  Is Soybean Lectin an Issue?  The Soy Nutrition Institute
The latest findings in soy health research,

Perkins, S.  2018. What Happens if You Eat Raw Soybeans?

Vagadia, B. H., Vanga, S. K., Raghavan, V. 2015.  Inactivation methods of soybean trypsin inhibitor – A review. Received 14 December 2015, Revised 21 January 2017, Accepted 19 February 2017, Available online 27 February 2017. Elsevier. Trends in Food Science & Technology, Volume 64, June 2017, Pages 115-125

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Counting Nitrogen Atoms – The History of Determining Total Meat Content (Part 5): The Proximate Analysis, Kjeldahl and Jones (6.25)

Determining Total Meat Content (Part 5): The Proximate Analysis, Kjeldahl and Jones (6.25)
By Eben van Tonder
5 January 2019

agriculture stations

For part 1, 2, 3 or 4, click on:

Part 1:  From the start of the Chemical Revolution to Boussingault

Part 2:  Von Liebig and Gerard Mulder’s theory of proteins

Part 3:  Understanding of Protein Metabolism Coming of Age

Part 4:  The Background of the History of Nutrition


We have progressed in our study of the historical development of the concept of using Nitrogen to determine meat content to the Proximate analysis, and its accompanying use of the Kjeldahl method, the Jones factors and a review of the nutritional importance of the Proximate system.  Our study leads us to unexpected places as we are challenged in our views on managing a complex operation like a large food factory.

Food Analysis

The history of the development of food analysis goes back to the people we met in our introductory articles in the persons of Baussingault, and Liebig.  To the list, we should probably add Sir Humphrey Davey, but Davey held a fundamentally different view of nutrition compared to Liebig and Baussingault.  Where these two men held the basis for plant nutrition to be mineral, Davey was in the camp of Albrecht Daniel von Thaer (1752-1828) on the subjected who believed humus to be the foundational principle of plant nutrition.  “According to this theory, humus is the main source of plant nutrients, next to the previously recognized role of water, obviously. In Thaer’s opinion, minerals played only a supporting role in providing plants with humic compounds. Therefore, the whole soil fertility depends only on the amount of humus present in it. He presented his views in his work “The Principles of Agriculture”.”  (Antonkiewicz and Łabetowicz,  2016)

“The humus theory for plant nutrition was the dominant concept explaining the essence of plant nutrition for tens of years. Von Liebig was the first to explain, through his experimental works, the basics of the problem of mineral plant nutrition.  In 1841, a publication entitled “Die Organische Chemie in ihrer Anwendung auf Agrikultur und Physiologie” – “Organic Chemistry in Its Applications to Agriculture and Physiology” was released, with a new theory of mineral plant nutrition. This book opens a new chapter in the development of the science of plant nutrition. It attracted great interest not only in scientific world but also among a lot of farmers. Liebig wrote that not humus but mineral salts (are taken up with water by roots from soil) and carbon dioxide assimilated from air in the photosynthesis process are the direct food for plants. For stable plant yields, soil should be supplied with mineral fertilizers in order to replenish the deficiency of nutrients caused by their removal from the field along with plant yield. Liebig formulated his theory about mineral plant nutrition based on other scientists’ studies, and also through deduction from a chemical analysis of plants. As a chemist and analyst, he conducted many studies on the chemical composition of plants. He determined that plants release carbon, hydrogen, oxygen and nitrogen (which are present in them) during combustion, and composition of the generated ash always includes phosphorus, sulfur, calcium, potassium, magnesium, silicon, and many times sodium.”  (Antonkiewicz and Łabetowicz,  2016)

In the end, it was the scientific rigor of Liebig that won the day.  Not just his new techniques opened up new discoveries, but also the question if science and practice presented a duality.  These two concepts were juxtaposed in the mind of the landowners who saw the views of Liebig and Albrecht Daniel von Thaer as much more than a debate about the essence of plant nutrition.  Liebig’s word was scientific and based in a laboratory.  Of course, it had to have practical application, but he wrestled with solving fundamental questions first before he moved on to the practical and in many instances, as we know from our own experiences, even the best scientific work don’t always work in practice at the first attempt.  Such is the nature of the beast.

Von Thaer, on the other hand, was a consummate pragmatist and by all accounts, a skilled manager.  I am impressed by the reported neatness of the workshops on the estates that he was in charge off.  Reports have it that they were open for inspection by the public and everything had its place.  Thaer’s work, “Principles of Agriculture” contain the result of his experience through a series of years. We can feel his passion and approach in his work.  It embraces the theory of the soil, the clearing of land, plowing, manuring, and irrigation, hedges and fences, management of meadow and pasture lands; the cultivation of wheat, rye, corn, oats, barley, buckwheat, hops, tobacco, clover, and all the varieties of grasses; the economy of kine stock, breeding and feeding; the management of the dairy, and the use of manures, and the various systems of cultivation, keeping journals and farm records. In brief, it is a complete cyclopedia or circle of practical agriculture.  (Homans, 1857)

These issues that we don’t necessarily see as opposing views today would take on a life of its own in Germany which impacted (determined?) the course of history related to the nutritional sciences and the evaluation of foods.

As Liebig’s approach of rigorous science and experimentation started to dominate, tools were being developed on which more discoveries were predicated.  Better techniques were developed, gradually, to separate the food fragments which played a role in nutrition including protein, fat, and fiber.  The Liebig/ Dumas method for example, for determining the Nitrogen content in food was developed in 1830 and 1840.  The famous Kjeldahl method was published in 1883 and much later the use of the 6.25 conversion number of N to protein would become the more complete Jones numbers.  At the dawn of the 20th century, food chemistry was firmly established.  (Dryden, 2008)  Along with improved techniques and tools, the philosophical wars raged on.

The Proximate Analysis


The German Agriculture Research Stations was a driving force in the development of German farming from the mid-1800s and a model for similar developments around the world.   Wilhelm Crusius has it that the first German Agricultural Research Station was created on 28 September 1850 during a banquet honouring Leipzig’s new marble statue of Albrecht Daniel von Thaer.  He recalls that several agricultural leaders from the kingdom of Saxony agreed to terms that saw the Möckern estate near Leipzig transformed into an institution to investigate the application of scientific knowledge to agriculture.  The Möckern facility is widely believed to be the words first state-supported agriculture research station.  It was believed that the Möckern facility represented a fulfillment of Thaer’s vision.  He propagated a system of “rational” agriculture.  Landowners loved him as they looked for ways to increase their yields through comparative investigations, but was skeptical of what we call research.  (Finlay, 1988)

It is generally believed to be Liebig who founded the agriculture research stations, through his 1840 work Chemistry and its application to Agriculture and Physiology.  Many suggested that it was the excitement created by this publication around the world, that Germanys research stations were founded upon. It is believed by many that the agricultural research station became a haven for the agricultural chemists.  The line of thinking then continues that the Americal Agricultural stations were created based on the German model in the 1870’s and 80’s.  Even the notion of research is also linked to Liebig through his famous research laboratory in Giesen.  (Finlay, 1988)

A study of the Möckern facility challenge these notions.  Fundamental science and agriculture chemistry were not, in fact, initial driving forces behind this first agriculture station.  The Saxon officials had praise for Liebig’s recognition of the importance of chemical compounds in plants and animal growth but scorned his insistence on laboratory research.  Liebig created a plant manure in his laboratory.  It was practically insoluble.  A white chemical crust formed over fields in practical demonstrations and his invention was a disaster.  Many believe that the creation of the agriculture stations would provide an opportunity to verify such work.  They saw a division between science and practice and the stations would be a place to unite these two polar opposites.  In the early days of the Möckern facility, scientists and what was called “practitioners” had equal authority.  As in America, in Germany, the scientists did not win control over these stations for some time and not after a long and hard battle. (Finlay, 1988)

In a 1988 article, The German Agricultural Experiment Stations and the Beginnings of American Agricultural ResearchFinlay brilliantly examines the leading forces behind the creation of the agricultural stations and the duel between those who relied on science and those who held practice to be superior.

The German Agriculture Experiment stations became the model for similar stations set up in America.  Wilbur Atwater of Connecticut had great admiration for the Möckern station.  He got involved in work at another station, the one at Weende.  Here they were involved in calorimeter research in the 1860’s and  Atwater expended on the research. (Marcus, 2015)

Weende Experiment Station

The physiological chemistry work of Liebig had only an indirect application in agriculture. Wilhelm Henneberg was one of his students who applied his theories and methods directly in agriculture research.  This would be one example of the triumph of science and laboratory research and fundamental to our understanding of the current methods for determining meat content.  Scientists at these research stations directed the priority of work away from the achievement of immediate practical goals and towards the examination of basic scientific questions.  Henneberg became the director at the Agriculture Experiment Station at Weende near Göttingen in 1857.  He made a huge contribution to this shift and introduced a program using livestock as experimental organisms, incorporating the methods and instruments that he was introduced to in Munich.  Precision and quantification were very important to him.  He used instruments like the Petterkoffer respiration apparatus.  (Phillips and Kingsland, 2015)

RESPIRATION APPARATUS, PETTENKOFER AND VOIT.pngHe stressed the importance of controlling environmental variables in laboratory settings and focused on fundamental questions in animal metabolism.  His assistant was Frederich Stohmann who helped with the findings of his experiments.  They directed the findings at farmers and physiologists, but in reality, made no effort to practically apply the results of their work. (Phillips and Kingsland, 2015)

Henneberg challenged the view of Thaer who emphasised close interaction of science and practice and the integration of plant and animal agriculture.  Agriculture sciences rose to great prominence in Germany during this time and animal nutrition was one of its most successful branches.  (Phillips and Kingsland, 2015)

Henneberg and Stohmann (1860, 1864) developed a top level, very broad, classification of food components for routine analysis which they devised for animal feed.  It is a “partitioning of compounds in feed into six categories based on the chemical properties of the compounds.   This analysis was an attempt to duplicate animal digestion.  (Artemia)

After extracting the fat, the sample is subjected to an acid digestion, simulating the acid present in the stomach, followed by an alkaline digestion, simulating the alkaline environment in the small intestine. The crude fiber remaining after digestion is the portion of the sample assumed not digestible by monogastric animals. In the proximate analysis of feedstuffs, Kjeldahl nitrogen, ether extract, crude fiber, and ash are determined chemically. The determination of nitrogen allows the calculation of the protein content of the sample. It is important to remember that proximate analysis is not a nutrient analysis, rather it is a partitioning of both nutrients and non-nutrients into categories based on common chemical properties.” (Artemia)

“At that time the nutritionally important components of protein had not been recognized, all neutral fats were considered to be nonspecific sources of energy, and vitamins were unknown. However, the multiplicity of the carbohydrates and the practical difficulties of their separate chemical determination were clearly recognized. These workers believed that for nutritional description the carbohydrates could be grouped into (1) the starches and the sugars, and (2) a coarse fibrous fraction. The latter they isolated as an insoluble residue after boiling the food sample first with dilute acid and then with dilute alkali. These procedures were intended to simulate the acidic gastric digestion and the subsequent alkaline intestinal digestion of ingested food. The insoluble residue they called crude fiber.  With analytical figures for ether extract, ash, nitrogen, and crude fiber of a moisture-free food sample, they needed only to convert the value for nitrogen to its equivalent in terms of protein (i.e., N x 6.25), add to this the other three group values, and subtract the total from the original weight of dry sample,
thus by difference to arrive at an estimate of the “soluble carbohydrates.” This fraction they called nitrogen-free extract (NFE).”  (Loyed, et al.  1960)

“The majority of foods in human diets, as well as those in the diets of some laboratory animals used in nutrition studies, are so low in crude fiber that this fraction can often be disregarded, and the custom has gradually become general, especially in human nutrition, to omit the crude fiber determination. When this is done it is the total carbohydrate that is estimated “by difference.”  (Loyed, et al.  1960)

“Probably because the chief components of nitrogen-free extract (NFE) are sugars and starches, we are prone to forget that this fraction includes all the nonfibrous, ether-insoluble, water-soluble organic materials of the food (or other material analyzed). Thus all water-soluble vitamins must be included in this fraction. Quantitatively, the vitamins are an insignificant part of the NFE, but in any broad charting of the makeup of foods in terms of the Weende partition these vitamins are part of the NFE in the same way that the fat-soluble vitamins are part of ether extract.”  (Loyed, et al.  1960)

“Being determined by difference, the figure for NFE is also subject to an appreciable but variable error that may be as large as the algebraic sum of any analytical and/or sampling errors of each of those fractions determined by direct analysis.

Variability of average

Weende analysis values

It is appropriate at this point to comment on the errors to be expected in numerical values obtained from the several parts of the Weende analysis. These arise from several sources. Errors in the chemical manipulations-that is, analyst’s errors are usually negligible. Sampling errors, however, are often large because foods and the residues of animal digestion are not usually homogeneous. In addition, different lots of foods called by the same name are seldom identical in “proximate” makeup. Consequently, average composition figures found in tables of food composition are not necessarily applicable to a particular lot of a foodstuff. Nevertheless, it is often more feasible to estimate the protein, or the fat, or the carbohydrate, of some particular lot of a foodstuff by referring to tables of average composition than to obtain specific values by analysis. When average values are used in this way it should be remembered that the composition figures given for natural foods may be subject to coefficients of variation such as those listed in the table below.”  (Loyed, et al.  1960)

coefficients of variables.png

“For example, if the average crude protein content of corn meal is given in a table as 10%, it is probable that two samples out of three purchased at random would on analysis give values between 9.2 [10 minus 10 (8%)] and 10.8 [10 plus 10(8%)] percent protein (see figure above). Similarly, cornmeal may average 72% NFE, and hence two samples out of three might be expected to give values between 69.8% and 74.2% (that is, 72 ± 3%).” (Loyed, et al.  1960)

This current application of this system of analysis can be summarised as follows: 

  •  moisture,

The moisture content is determined as the loss in weight that results from drying a known weight of food to constant weight at 100 degrees C. This method is satisfactory for most foods, but with a few, such as silage, significant losses of volatile material may take place.

  •  ash,

The ash content is determined by ignition of a known weight of the food at 550°C until all carbon has been removed. The residue is the ash and is taken to represent the inorganic constituents of the food. The ash may, however, contain material of organic origin such as sulphur and phosphorus from proteins, and some loss of volatile material in the form of sodium, chloride, potassium, phosphorus, and sulphur will take place during ignition. The ash content is thus not truly representative of the inorganic material in the food either qualitatively or quantitatively.  There is incomplete recovery of individual minerals.  It is one of the aspects of the proximate analysis, less used in modern food analysis.  (  “Ash is a mixture of food minerals.   The food Organic Matter (OM) content is  (OM = DM – ash) is frequently used as a way of correcting data for mineral contamination, as will happen when measurements are made with grazing animals.” (Dryden, 2008)

  •  crude protein,

The crude protein (CP) content is calculated from the nitrogen content of the food, determined by a modification of a technique originally devised by Kjeldahl over 100 years ago. In this method, the food is digested with sulphuric acid, which converts to ammonia all nitrogen present except that in the form of nitrate and nitrite. This ammonia is liberated by adding sodium hydroxide to the digest, distilled off and collected in standard acid, the quantity so collected being determined by titration or by an automated colourimetric method. It is assumed that the nitrogen is derived from protein containing 16 percent nitrogen, and by multiplying the nitrogen figure by 6.25 (i.e. 100/16) an approximate protein value is obtained. This is not ‘true protein’ since the method determines nitrogen from sources other than protein, such as free amino acids, amines and nucleic acids, and the fraction is therefore designated crude protein.  (

The Dumas method in which a sample is burnt and the N gas released is measured, was developed before the Kjeldahl method but has become popular only following the development of automated methods of carrying out the analysis.  The method recovers all the sample N and so may give slightly higher values than the Kjeldahl method, depending on the sample analysed.” (Dryden, 2008)

  •  ether extract,

The ether extract (EE) fraction is determined by subjecting the food to a continuous extraction with petroleum ether for a defined period. The residue, after evaporation of the solvent, is the ether extract. As well as lipids it contains organic acids, alcohol, pigments, fat-soluble vitamins, waxes, as well as fats.  ( It is used to isolate lipids for more detailed fractionation into fatty acids and waxes.  The EE is, nevertheless, still reported as a measure for total lipid.  In the current official method, the extraction with ether is preceded by hydrolysis of the sample with sulphuric acid and the resultant residue is the acid ether extract.  (Dryden, 2008)

  • crude fibre, and

Einhof extracted the fibrous part of food in 1805.  His concept of fiber is very distant from our present-day understanding.  To him, it was what was obtained after rubbing and washing the food to obtain the residue that is “resistant.”  He may have thought that it was not nutritious.  Boussingault and Davy specifically stated that it is not since it could not be digested.  They had no experimental proof of this.  (Dryden, 2008)  Henneberg and Stohmann developed a method for analyzing crude fiber in 1859.    The carbohydrate of the food is contained in two fractions, the crude fibre (CF) and the nitrogen-free extractives (NFE). The former is determined by subjecting the residual food from ether extraction to successive treatments with boiling acid and alkali of defined concentration; the organic residue is the crude fibre.  (

  • nitrogen-free extractives.

When the sum of the amounts of moisture, ash, crude protein, ether extract and crude fibre (expressed in g/kg) is subtracted from 1000, the difference is designated the nitrogen-free extractives. The crude fibre fraction contains cellulose, lignin, and hemicelluloses, but not necessarily the whole amounts of these that are present in the food: a variable proportion, depending upon the species and stage of growth of the plant material, is contained in the nitrogen-free extractives. Nitrogen Fee Extracts (NFE) was originally assumed to be mainly soluble carbohydrate and so was expected to be highly digestible.  The nitrogen-free extractives fraction is a heterogeneous mixture of all those components not determined in the other fractions. It includes sugars, fructans, starch, pectins, organic acids, and pigments, in addition to those components mentioned above.  (

“Unfortunately, the reagents used to measure crude fibre (CF), may remove up to 60% of the cellulose, about 80% of the hemicellulose and a highly variable (10 – 95%) proportion of the lignin.The NFE contains some of the plant cell wall material an can be less digestible than CF.  Besides this, NFE contains all those chemical entities which are not measured by the other methods.  NFE is not now used in food analysis.”  (Dryden, 2008)


Schematically, it can be represented as follows: (chart by (Dryden, 2008))

The Proximate Analysis of Food.png

This system had a long-lasting effect on our approach to food analysis.  We still use Dry Matter as the basis for expressing analytical data in calculating food intake of formulating diets.  (Dryden, 2008)

N is important

Nitrogen is important for meat curers due to the role of NO formation from NO2- in the curing reaction.  Have a look at my 2016 article, Mechanisms of meat curing – the important nitrogen compounds, and  Reaction Sequence: From nitrite (NO2-) to nitric oxide (NO) and the cooked cured colour.  Nitrogen in organic material is present in the form of amine groups (-NH2) as constituents of amino acids (proteins) and amino sugars and measuring it is important to a study of proteins and nutrition in general.

“The chemistry of nitrogen is complex due to the fact that nitrogen assumes several oxidation states (Sawyer et al., 2003). Nitrogen is one of the most important elements for plant nutrition. The compounds of nitrogen are of great worth in water resources, in the atmosphere, and in the life process of all plants and animals. Four forms of dissolved nitrogen are of greater interest: organic, ammonia, nitrite, and nitrate, ordered in an increasing state of oxidation. All these forms of nitrogen, as well as nitrogen gas (N2), are mutually convertible, being components of the biological nitrogen cycle (Pehlivanoglou-Mantas and Sedlak, 2006; Worsfold et al., 2008). It is very important to ascertain the contribution (fractions) of different nitrogen species to the total nitrogen content (Prusisz et al., 2007).

Testing for N

The modern version of the proximate analysis uses mostly the Kjeldahl method of testing for N.  Few other companies in history had such a dramatic effect on chemistry in general and food chemistry in particular as the Danish beer producer, Carlsberg.   S.P.L. Sørensen was Director of the Carlsberg Laboratory’s Department of Chemistry from 1901 to 1938. In 1909, he developed the pH scale – a method for specifying the level of acidity or alkalinity of a solution on a scale from 0-14 and demonstrated the significance of pH for biochemical reactions, including those involved in brewing.  With the invention of the pH scale, Carlsberg could ensure high quality of every beer. The applications of the pH scale have since been countless throughout all fields. (

It is remarkable that more than 20 years before the pH scale was invented, his predecessor from the same institution invented the definitive measurement for N in protein.  Here is the story, told by Sáez-Plaza, et al. in their  Overview of the Kjeldahl Method of Nitrogen Determination, Part I and Part II.

“The Danish chemist Johan Gustav Christoffer Thorsager Kjeldahl (1849–1900), Head of Chemistry Department of the Carlsberg Foundation Laboratory of the Danish Brewing Carlsberg Company, introduced a method known later under the eponym the Kjeldahl method that basically is still in use. It was first made public at a meeting of the Danish Chemical Society (Kemisk Forening) held on March 7, 1883 (Burns, 1984; Johannsen, 1900; McKenzie, 1994; Oesper, 1934; Ottensen, 1983, Veibel, 1949). Within the same year, the method was published in the German journal Zeitschrift f¨ur Analytische Chemie (Kjeldahl, 1883a), and written in French and Danish languages in communications from the Carlsberg Laboratory (Holter and Møller, 1976; Kjeldahl, 1883b, 1883c; Ottesen, 1983).”  (Sáez-Plaza, et al, 2013)

“Because of the respect that the founder of the laboratory, the Danish brewer J. C. Jacobsen, had for Pasteur and his work for the French wine industry (Burns, 1984), extensive French summaries of the Carlsberg papers were also published. As an extended summary of the Kjeldahl paper appeared in Chemical News in August (Kjeldahl, 1883d), the method was quickly taken up (Sella, 2008). The Analyst first gave details of the method in 1885 “for the benefit of those who may have missed the original paper” (Burns, 1984; Editor of The Analyst, 1885, p. 127), although the method had been briefly mentioned by Blyth (1884), who gave Kjeldahl’s name incorrectly as Vijeldahl. A surprisingly short period went by between the publication of the Kjeldahl method and the appearance of publications effecting further improvements (Dyer, 1895; Hepburn, 1908; Kebler, 1891; Vickery, 1946a), both in Europe and the U.S., due to the tremendous impact that the Kjeldahl work had on others, especially in Germany (McKenzie, 1994).

Most of the earlier contributions were discussed by Fresenius in the Zeitschrift, often to a length of several pages (Vickery, 1946a). Throughout the history of analytical chemistry, none of the methods has been as widely adopted, in so short a time, as the “Kjeldahl Method” for the estimation of nitrogen, as stated by Kebler (1891) at the beginning of an annotation in which he compiled references on the estimation of nitrogen by the Kjeldahl method (some 60) and by all other methods (about 200).” (Sáez-Plaza, et al, 2013)

“The Kjeldahl method was originally designed for the brewing industry as an aid in following protein changes in grain during germination and fermentation (Bradstreet, 1940; Kjeldahl, 1883b); the lower the amount of protein in the mush, the higher the volume of beer produced. It was Berzelius who suggested the use of the word “protein” in 1838 in a letter to Mulder because it was derived from the Greek word meaning “to be in the first place” (Zelitch, 1985). The Kjeldahl protein content is strictly dependent on total organic nitrogen content (Wong et al., n.d.); i.e., protein structure will not interfere
with the accuracy of protein determination.”

As we have mentioned earlier in this article, a drawback of the Kjeldahl method is that it lacks the “analytical selectivity because it does not distinguish protein-based nitrogen from nonprotein nitrogen. Adulteration incidents (e.g., adulteration of protein-based foods with melanine and related nonprotein compounds) exploiting this analytical vulnerability have been recently detected (Breidbach et al., 2010; Levinson and Gilbride, 2011; Moore et al., 2010; Tyan et al., 2009) and are new examples of a problem that dates back to before the Kjeldahl method was introduced (M¨oller, 2010a).” (Sáez-Plaza, et al, 2013)

“The presence of non-protein nitrogen (NPN) compounds in foods (aminoacids, ammonia, urea, trimethylamine oxide) overestimates their true protein content (M¨oller, 2010a; van Camp and Huyghebaert, 1996; Yuan et al., 2010) as derived from the current nitrogen determination methods. Separation of NPN from true protein nitrogen may be carried out by adding a protein precipitating agent such as trichloroacetic acid or perchloric acid (Rowland, 1938a, 1938b). The process conditions applied during protein precipitation, however, affect the composition and the amount of NPN, so it is mandatory to specify the type and concentration of precipitating agents used in each case. Alternative techniques such as dialysis and gel filtration are probably more accurate in removing the NPN fraction (van Camp and Huyghebaert, 1996), but they remain unacceptable for routine analysis. Reviews of NPN determination methods in cow milk, and on aspects concerning the composition of NPN fraction, are given by Wolfschoon-Pombo and Klostermeyer (1981, 1982). The Kjeldahl method measures what is termed total protein (American Jersey Cattle Association, n.d.). The alternative use of true protein (total nitrogen minus the NPN) has been under debate for some years (Grappin, 1992; Harding, 1992; Rouch et al., 2007; Salo-V¨a¨ananen and Koivistoinen, 1996). A fundamental change in milk pricing in the U.S. was introduced January 1, 2000 with the implementation of producer payments in Federal Milk Marketing orders on the basis of the true protein content (American Jersey Cattle Association, n.d.; Stephenson et al., 2004; Zhao et al., 2010).” (Sáez-Plaza, et al, 2013)

“The protein content in a foodstuff is estimated by multiplying the nitrogen content by a nitrogen-to-protein conversion factor, usually set at 6.25 (Comprehensive Review of Scientific Literature . . . , 2006; Mariotti et al., 2008), which assumes the nitrogen content of proteins to be 16%. It is not clear who first reported such a factor for use (Moore et al., 2010). This general conversion factor is used for most foods because their non-protein content is negligible. However, pure proteins differ in terms of their nitrogen content because of differences in their amino acid composition, ranging from 13.4% to 19.3%; different multiplying factors are suitable for samples of different kinds. The factor 5.7 is applied for wheat and 6.38 for dairy products (O’Sullivan et al., 1999) and 6.394±0.004 for cheddar cheese, as shown recently (Rouch et al., 2008). The proximate system where protein is measured as total nitrogen multiplied by a specific factor clearly dominates food composition studies (Greenfield and Southgate, 2003). As a matter of fact, most
cited values for protein in food composition databases derive from total nitrogen or total organic nitrogen values.” (Sáez-Plaza, et al, 2013)

“A large variety of food proteins, either from animals (milk, meat, eggs, blood, fish) or plants (seeds, cereals), is nowadays available in the food industry. The determination of protein in foods and food products has important nutritional, functional, and technological significance (Van Camp and Huyghebaert, 1996). The protein content determines the market value (Krotz et al., 2008; Wiles et al., 1998) of major agricultural commodities (cereal grains, legumes, flour, oilseeds, milk, and livestock feeds). In addition, the quantitative analysis of protein content is necessary for quality control, and also a prerequisite for accurate food labeling (Owusu-Apenten, 2002). Protein analysis is required for a very wide range of animal and human nutrition products. Consumer interest in soy protein products has increased rapidly in Western cultures in recent years. This trend is due in part to the high-quality protein of soy foods and soy protein ingredients and in part to their associated health benefits (Jung et al., 2003); 25 g of soy protein per day may improve cardiovascular health (U. S. Food and Drug Administration, 1999). Consequently, precise determinations of protein content of soy products are very important. Total nitrogen concentration in soils is one of the most frequently measured
nutrients in soil-testing laboratories (Sharifi et al., 2009). Determination of nitrogen content plays a key role in assigning values to insulin reference materials (Anglow et al., 1999). Primarily devised for the determination of protein nitrogen, the Kjeldahl method has been extended to include the determination of various other forms of nitrogen, e.g., in soils, plant materials, biological tissues, and wastewater matrices (Chemat et al., 1998). (Sáez-Plaza, et al, 2013)

“Though the Kjeldahl procedure is hazardous, lengthy, and labor intensive, it has become the industry standard; it remains an accurate and reliable method and is used to standardize other methods (ISO, 2009a, 2011; Orlandini et al., 2009a; Orlandini et al., 2009b; Rayment et al., 2012). Semiautomated or fully automated nitrogen (protein) analysis systems based on the classical Kjeldahl procedure (Rhee, 2001; Wright and Wilkinson, 1993) are preferable in order to cut cost and to save time when a large number of samples need to be analyzed.”  (Sáez-Plaza, et al, 2013)

The automation of chemical methods used routinely in research can lead to a considerable saving in time and labor and, thus, efficiency in carrying out a particular piece of work (Davidson et al., 1970; Feinberg, 1999). Automation makes it possible to avoid direct handling of dangerous reagents (Pansu and Gautheyrou, 2006), such as boiling sulfuric acid or concentrated soda. Ferrari (1960) succeeded in automating the Kjeldahl nitrogen procedure, describing the new concept of continuous nitrogen determination. The automated macro Kjel-Foss analyzer was introduced in 1973, with which one can routinely perform 20 analyses/hour (Oberreith and Neil, 1974). Various degrees of automation are available for the Kjeldahl method, including automated digestion and distillation followed by manual titration; fully automated digestion, distillation, and titration; and the use of block digesters and autosamplers for the unattended analysis of a maximum of 60 samples per batch. Semiautomated equipment is available with digestion and distillation determination units at macroscale and microscale from, for example, the manufacturers Bicasa, B¨uchi, Gerhardt, Skalar, Foss-
Tecator, and Velp (Pansu and Gautheyrou, 2006; Pansu et al., 2001). Depending on the analysis procedure used, the scale of operation applied, and the degree of automation installed, the analysis time of the procedure could be further reduced, corresponding to frequencies of analysis up to 20 samples/hour.”  (Sáez-Plaza, et al, 2013)

Jones Factors

An important feature of the Proximate Analysis is the conversion of measured nitrogen to protein by multiplying total N by a factor to estimate the total protein content.  It is still used for its simplicity and relative accuracy.  The commonly used factor is 6.25 derived from the fact that protein contains 16% nitrogen.  100/16 = 6.25. Who the first person is to use this factor is not known.   N in food can be measured by the Kjeldahl Method (1883) in which protein-N is dissociated from its combination with other elements by digestion in concentrated sulfuric acid (H2SO4) followed by conversion to the hydroxide and subsequent distillation and titration.”  (Dryden, 2008)

“Jones, Munsey and Walker (1942) measured the nitrogen content of a wide range of isolated proteins and proposed a series of specific factors for different categories of food. These factors have been widely adopted and were used in the FAO/WHO (1973) review of protein requirements. These are listed in the table below. Several authors have criticized the use of these traditional factors for individual foods (e.g. Tkachuk, 1969).  Heidelbaugh et al. (1975) evaluated three different methods of calculation (use of the 6.25 factor, use of traditional factors and summation of amino acid data) and found variations of up to 40 percent. Sosulski and Imafidon (1990) produced a mean factor of 5.68 based on the study of the amino acid data and recommended the use of 5.70 as a factor for mixed foods.

In principle, it would be more appropriate to base estimates of protein on amino acid data (Southgate, 1974; Greenfield and Southgate, 1992; Salo-Väänänen and Koivistoinen, 1996) and these were incorporated in the consensus document from the Second International Food Data Base Conference held in Lahti, Finland, in 1995, on the definition of nutrients in food composition databases (Koivistoinen et al., 1996).

If these recommendations are to be adopted, the amino acid data should include values for free amino acids in addition to those for protein amino acids because they are nutritionally equivalent. The calculations require very sound amino acid values (measured on the food) as discussed below, and involve certain assumptions concerning the proportions of aspartic and glutamic acids present as the amides and correction for the water gained during hydrolysis. Clearly, this approach would not be very cost-effective when compared with the current approach.

At the present time, it is probably reasonable to retain the current calculation method, recognizing that this gives conventional values for protein and that the values are not for true protein in the biochemical sense. However, it is important to recognize also that this method is not suitable for some foods that are rich in non-amino non-protein nitrogen, for example, cartilaginous fish, many shellfish and crustaceans and, most notably, human breast milk, which contains a substantial concentration of urea.

Factors for the conversion of nitrogen values to protein (per g N)*
Foodstuff Factor
Animal products
Meat and fish 6.25
Gelatin 5.55
Milk and milk products 6.38
Casein 6.4
Human milk 6.37
whole 6.25
albumin 6.32
vitellin 6.12
Plant products
whole 5.83
bran 6.31
embryo 5.8
endosperm 5.7
Rice and rice flour 5.95
Rye and rye flour 5.83
Barley and barley flour 5.83
Oats 5.83
Millet 6.31
Maize 6.25
Beans 6.25
Soya 5.71
almond 5.18
Brazil 5.46
groundnut 5.46
others 5.3
* (Where a specific factor is not listed, 6.25 should be used until a more appropriate factor has been determined.)
Source: FAO/WHO, 1973.

A number of direct methods for protein analysis have been developed for specific foods based on reactions involving specific functional groups of the amino acids present; these are thus not applicable to the measurement of proteins in general. Such methods include formol titration (Taylor, 1957) and the biuret reaction (Noll, Simmonds and Bushuk, 1974). A widely used group of colorimetric methods is based on reaction with Folin’s reagent, one of the most widely used biochemically in the dairy industry (Lowry et al., 1951; Huang et al., 1976). These methods are most commonly calibrated with bovine serum albumin, which is available at high purity.”  (Greenfield and Southgate, 2003)

Nutrient makeup of proximate principles

The Proximate Analysis is not used for deriving nutritional values, but it is still important, before leaving this subject, that we should specifically relate it to several nutrients. “We shall thus also delimit the extent to which the Weende scheme can be expected usefully to describe specific nutrients and groups of nutrients found in the animal body and in its food.” (Loyed, et al.  1960) I quote this from a Loyed, et al.  who was published in the 1960.  Despite the age of the work, I find it remarkably complete as an introduction to the subject.

“Carbohydrates The total number of edible materials that are carbohydrate by definition is large. There are, for example, a dozen or more that are found in everyday foods, either as one of six or seven “sweet” sugars, or in combinations of them comprising numerous more complex molecules such as the starches, hemicelluloses, or celluloses. The monosaccharide sugars are classified according to the number of carbon atoms in their molecules. Thus there are 5-carbon or pentose sugars, and 6-carbon or hexose sugars. All pentose sugars have the same empirical formula, C5H10O5; the empirical formula for all hexoses is C6H12O6.  The complex carbohydrates are merely polymers of the simple sugar units, as (C5H8O4)or (C6H10O5)n. Cellulose, for example, has been estimated to consist of 1000-2000 hexose units polymerized into the long fibrous chains characteristic of the cellulose structure. The distribution of the carbohydrates between the Weende nitrogen-free extract and crude fiber fractions is shown in the table below.”  (Loyed, et al.  1960)

carbohydrates and their distribution in Wheende NFE.png

“It will be seen that the carbohydrate portion of our foods and feeds consists either of single 1-carbon or 6-carbon units, or of larger molecules formed by combinations of such structures. Before the larger molecules can be useful in nourishing the body they all must be degraded by enzymes in the digestive tract to their simple 5- or 6-carbon units; or, in the case of cellulose and perhaps of some of the hemicelluloses, to either the 2-, 3-, or 4-carbon molecules of acetic, propionic, or butyric acids, respectively. (These three acids are products of digestion by microflora inhabiting the digestive system of animals, such as herbivores.)”  (Loyed, et al.  1960)

“The nutritional significance of the fact that carbohydrates are all assemblies
of 5- or 6-carbon units is that they have potentially about the same energy value, roughly between 3.75 and 4.25 kilocalories per gram of dry substance. Except for small amounts of ribose, carbohydrates can be considered useful primarily as sources of energy. These facts make it clear that even though the carbohydrate portion of a food or a diet is estimated “by difference” in the Ween de scheme of analysis, little, if any, useful information is lost by this group treatment.”  (Loyed, et al.  1960)

“The digestible or the metabolizable energy the body ultimately obtains from the nitrogen-free extract, from the crude fiber, or from the total carbohydrate (i.e., the nitrogen-free extract plus the crude fiber) of a food, is a somewhat different matter, since the completeness of the digestion of these two groups of carbohydrates is often appreciably different. This matter will be considered later when the question of digestibility is dealt with. For the moment it will suffice to note that celluloses and hemicelluloses yield less useful energy to nonherbivores than do the carbohydrates of the nitrogen-free extract category.”  (Loyed, et al.  1960)

Crude protein Crude protein is also a group name; it refers collectively to the sum of up to 20 nutrients, the amino acids, each of which has one or more specific roles in metabolism. In addition, each of these protein components, if present in excess of that needed for its specific function, may, following absorption, be split into a nitrogen-containing entity NH3 and a deaminized residue, the latter becoming a nonspecific source of energy.”  (Loyed, et al.  1960)

“Most of the amino acid residues that can be metabolized for energy contain 3-carbon atoms. In any case, only that fraction of an amino acid that is equivalent to some intermediate in the metabolism of sugars (or of fats) is so used. However, the potential energy in proteins, as measured by their complete combustion in a bomb calorimeter, is considerably greater than that in carbohydrates. This is true because with protein, oxygen is required not only – to oxidize the carbon, but, unlike carbohydrate, is required also to oxidize some of the hydrogen atoms; and the heat of water formation is much higher than that of carbon dioxide. Thus, typical pure proteins yield 5.25-5.75 kilocalories of gross energy per gram.”  (Loyed, et al.  1960)
“Nevertheless, the amount of nutritionally useful energy of protein is not greatly different from that of carbohydrate. This is so because the amino group that is split off in the deaminization of each “discarded” amino acid forms urea, which is eliminated in the urine. Urea contains combustible carbon and hydrogen, and this part of the potential energy from protein is lost the body. In humans it amounts to about 1.25 kilocalories per gram of protein so that the maximum usable energy from typical protein does not exceed 5.50 – 1.25 or 4.25 kilocalories per gram; this is usually reduced further by the incompleteness of digestion to about 4 kilocalories per gram. This can be stated in another way: whereas carbohydrate yields to the body, on the average, about 95% of its potential energy, only some 70% of the potential energy of protein can be used to meet energy needs. Protein is obviously not normally the preferred source of energy in nutrition.”  (Loyed, et al.  1960)

urine structure.png
Urine structure

“Incidentally, crude protein, by itself, describes only the energy of this nitrogenous fraction of foods. Without other information, the figure for the amount of crude protein in a food gives no reliable clue to the makeup of its nutrient units, the amino acids. Of these acids, we shall learn more later. It is sufficient here to tabulate them as some of the nutrients that we must deal with in nutrition (see table below).”  (Loyed, et al.  1960)

amoni acid of foods according to indispensability in diet of humans

Lipids, fats, and ether extract  “In a beginning course in nutrition there is a tendency to use almost interchangeably the terms lipid, fat, and ether extract. In particular, when we record the total of the ether extractives, We often designate it merely as fat. This rather loose usage of these terms does not often lead us astray, for reasons that will become obvious as one delves deeper into the subject. But it may be well at the outset to define these terms in a more specific way, in order to have a clearer conception of what substances are included in that fraction of the Weende analysis called ether extract.”  (Loyed, et al.  1960)

“Lipids Ure naturally occurring substances soluble in organic solvents, such as diethyl ether. A classification of these substances is given in the table below.”  (Loyed, et al.  1960)

Calorie value of ether extract  “This classification does not include all of the substances that may be found in the ether extract of foods or of tissue of the animal body. In general, the presence of substances other than triglycerides in ether extract dilutes its useful energy. They are mentioned here chiefly to show what a mixture the ether extract of foods may be. In foods of animal origin, such as meat fats, lard, or butter, it may be composed almost entirely of triglycerides. But in foods of plant origin, as much as half the total ether extract may be composed of sterols, waxes, and various other lipids. Since the nonglyceride lipids yield little utilizable energy to animals, the caloric value of ether extract is characteristic of specific foods: a single energy value, such as 9 kilocalories metabolizable energy per gram, while perhaps satisfactory for the fats of animal origin, the refined vegetable oils, or the shortenings prepared from them, is usually too high for the ether extract of foods of plant origin.”  (Loyed, et al.  1960)

classification of lipids

“The usefulness of the ether extract of the Weende scheme as a source of energy is dependent almost entirely on its total content of triglycerides. Ether extract values by themselves give no indication of the particular fatty acids in the fraction, nor of the amount of nonglyceride lipid. These values, therefore, are only an indication of the energy of a feed, which in turn is subject to considerable variation from one type of feed to another because of the possible variation in the composition of the lipid fraction.”  (Loyed, et al.  1960)

Ash-the inorganic nutrients  “The Weende analysis includes an inorganic fraction-the total of the noncombustible substances of the material. The quantity of ash in a feed or in some biological product does not of itself give information about any specific nutrient, and frequently the figure is used only to calculate the amount of carbohydrate by difference. The combination of mineral elements found in foods of plant origin is so variable that the ash figure of our analysis is useless as an index of the quantity of any particular element, or even of the total of the nutritionally essential ones. In the case of certain animal products, such as bone, milk, or cheese, whose composition is relatively constant, the approximate quantities of calcium and phosphorus can be predicted from the total ash figure. Thus, so far as useful information about the inorganic nutrients of foods is concerned, the ash figure is merely a starting point for specific analysis for one or another of some 21 to 26 mineral elements required by the body, and for a few about which information may be needed because of their toxic nature.”  (Loyed, et al.  1960)

Classification of the nutrients

“To summarize this what we discussed here, the table below identifies the principal nutrients by name and indicates the fractions of the Weende analysis into which they fall.”

“The table makes it clear that the Weende analysis does not describe nutrients individually; when this is necessary, some other scheme of description must be used. But, in spite of limitations, the Weende analysis is the basis for the everyday chemical description of foods, body tissues, and excreta that are of concern in such calculations as the estimation of digestibility and utilization of foods and the establishment of feeding standards for all animal species.”  (Loyed, et al.  1960)

makeup of the proximate principles.png


The young man who took over from me as production manager at Woody’s Consumer Brands has a saying that managing a production department of a meat factory is a team sport.  On the one hand one needs the experienced manager’s approach of Albrecht Daniel von Thaer.  On the other hand, I know from first-hand experience the financially devastating effect if a management team gets a call on a scientific matter related to meat science wrong.  Managing a large food manufacturing concerns is the job of an experienced team, not a lone ranger or a single night in shining armour and discipline in science and discipline in management has equally valid places.

A week ago an old friend visited from the United States and as we discussed these matters he commented that no matter what detours we take, we seem to always get back to clear management principles laid down by people like Peter Drucker.  The study of the development of the proximate analysis and the examples of marrying good management and science as exemplified in the life of Carlsberg come to us through our analysis of the history of what led us to our current day determination of meat content in formulations.  It is a subject so rich. We gain from it on every level.


For part 6, click on

Counting Nitrogen Atoms – The History of Determining Total Meat Content (Part 6):  (being written)



Analytical Techniques in Aquaculture Research. Artemia Reference Center (Ghent University, Belgium)

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Mariotti, F., Tomé, D., Mirand, P. P..  2008.   Converting Nitrogen into Protein—Beyond 6.25 and Jones’ Factors Critical Reviews in Food Science and Nutrition, 48:2, 177 – 184.  Link to this article: DOI: 10.1080/10408390701279749, URL:

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Sáez-Plaza, P., Michałowski, T.,  Navas, M. J., Asuero, A. C.,  & Wybraniec, S..  2013.   An Overview of the Kjeldahl Method of Nitrogen Determination. Part I  Early History, Chemistry of the Procedure, and Titrimetric Finish, Critical Reviews in Analytical Chemistry, 43:4, 178-223, DOI: 10.1080/10408347.2012.751786 Link to this article:

Sáez-Plaza, P., Michałowski, T.,  Navas, M. J., Asuero, A. C.,  & Wybraniec, S.. 2013.  An Overview of the Kjeldahl Method of Nitrogen Determination. Part II.  Critical Reviews in Analytical Chemistry, 43:224–272, 2013 Copyright c! Taylor and Francis Group, LLC
ISSN: 1040-8347 print / 1547-6510 online DOI: 10.1080/10408347.2012.751787


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