MDM – Not all are created equal

 

** still being written; incomplete**

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 who and was key in the creation of the New Zealand curing operation, Hellers.  Together with his brother, 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.

Ettiene 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.

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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.

Definition

“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.)

Hard MDM

The different production methods of MDM can broadly be separated into hard and soft MDM.  Hard MDM is made from pork or beef where it will be hard to clear the bones from all the small meat bits.  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 where are subjected to high pressure which removes the skin, meat bits, connective tissue, etc. still stock 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)

Soft MDM

Soft MDM, on the other hand, is produced from meat 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, only 70% to 80% is equal to protein found in muscle meat. Of this, only 60% to 70% is equal to the protein found in muscle meat.
Consequently: Consequently:
– Much improved WBC; – 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
Consequently:
– Do not support firmness in final product
pH: between 6.2 and 6.4
Consequently:
– poor colour developmenty
– MDM only products exhibit a darker colour.

References:

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.

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