Poultry MDM: Notes on Composition and Functionality
by Eben van Tonder
5 July 2020
Background
The mechanical deboning of meat has its origins from the late 1940s in Japan when it was applied to the bones of filleted fish. In the late 1950s, the mechanical recovery of poultry meat from necks, backs and other bones with attached flesh started. (EFSA, 2013) A newspaper report from the Ithaca Journal, Wed, 30 Dec 1964 is the earliest reference I can find on Mechanically Deboned Meat (MDM) in America. It reports on research done at Cornell State College of Agriculture in an article entitled, “New Egg Package, Chicken Products Are Among 1964 Research Results.” It reports that “mechanically deboned chicken meat was put to use for the first time, and improvements were in new types of harvesting machines.”
It claims that MDM based products would be available from 1964. “Late in 1964 Cornwell researchers began preparing experimental chicken products from this meat, which resembles finely ground hamburger.” It said that the new chunky type chicken bologna, was introduced in three forms: Chicken Chunk Roll, which is half chunk meat, and Chicken Chunkalona, which is 25 per cent chunks and 75 per cent emulsion.”By 1969, several American universities were working on these products, including the University of Wisconsin.
By the early 1970s, the removal of beef and pork from irregularly shaped bones was introduced. Originally, the aim of MDM was to reduce the rate of repetitive strain injury (RSI) of workers caused by short cyclic boning work in cutting rooms of meat operations. A press was developed to accommodate this. The success of the approach resulted in a rapid acceptance of the principles and an incorporation of the technology across Europe and the USA.
As is the case with meat processing technology in general, despite recent developments of the process, the basic approach is still the same as the first machines that was built. Initially primitive presses derived from other types of industries were used to separate the meat from the bones, using pressures of up to 200 bar. A fine textured meat paste was the end-product, suitable for use in cooked sausages. Gradual technological improvements and pre-selection of the different types of flesh bearing bones pressed at much lower pressure (up to 20 bar) produced a coarse texture of higher quality meat that could no longer be distinguished from traditional minced meat (so called 3 mm or Baader meat).
Today, a wide variety of different products are available on the market from many different suppliers of every imaginable animal protein source. Legislation differs widely between different countries on the definition of MDM. They name and classify it differently and the astute entrepreneur will find opportunities in studying every aspect of this fascinating industry closely, especially in the maize of ever evolving legislation related to it around the world. As one country restricts its use on one front, other countries will be able to buy a particular grade or type at better rates and this will in turn open up opportunities in the buying-country’s market for new ways to use raw material which becomes available for it due to a drop in the price.
My own foray into this world took place during a year when Woody’s gave me the opportunity to spend almost a year working with companies in England. The project I worked on was high injection pork. During this time there were changes to legislation related to ground pork. I witnessed UK prices plummet on a commodity which, in retrospect, we should have pounced on, but I knew far too little about the sausage market to exploit the opportunity. My business partner in the company we founded and where neither of us are involved in any longer will certainly have a good chuckle remembering those days!
Between 10 May and 8 June 2012, at the Tulip plant in Bristol, England, we extended ground pork with 100% brine which was designed by a friend from Denmark. Brine was tumbled into the meat, heat set, chilled, frozen and sliced. Re-looking at the texture of the final product from photos I took, almost 8 years later to the day, I realise that we should have used it to create a fine emulsion for a sausage or loaves. Looking at the result of the 100% extension below, we could easily have targeted 150% or even higher. We could have landed the raw material at a very competitive price in SA if we created a fine emulsion base, extended 150% with rind emulsion added (instead of rusk) and used it as the basis for a number of fine emulsion based products at our factory in Cape Town. Evaluating what we did in Bristol, the heat setting, even in our course loaf-like product, was inadequate for proper gelation, which is clearly seen in the photos below.
All the photos related to these trails can be seen at: https://photos.app.goo.gl/LX6uZheqeBeUa1mWA
The lesson for me is that in order to exploit these realities, one must grasp the functional value of the raw material, which in our consideration here is MDM, but must most certainly include other similar products not necessarily classified as MDM, MRM or MSM such as ground meat or something similar. This will lead to an appreciation of the differences between various grades of MDM and related products, which will allow processors to develop new products and increase its bottom line / reduce selling prices of others as new MDM products become available and countries adjust its legislation to regulate its use. It all begins by understanding the basic principles at work in this immense and fascinating world. We begin by looking at the basics of poultry MDM.
I use the work of JM Jones as the basis for these considerations as was published in the work edited by Hudson, B. J. F.. Related to the functional characteristics, I rely on the work of Abdullah and Al‐Najdawi (2005). They set up to investigate the effects of either manual or mechanical deboning on the functional properties of the resultant meat and any changes that might occur in quality attributes, as measured by sensory testing. They also considered the effects of frozen storage. In their study, they compared 4 treatments: treatment 1: manual deboning of whole carcasses; treatment 2: manual deboning of skinned carcasses; treatment 3: mechanical deboning of whole carcasses; treatment 4: mechanical deboning of skinned carcasses. We will refer to these 4 treatments during our discussion below.
Production Methods, Meat Quality and Nomenclature
The process of mechanical deboning involves crushing the bones and mixing with meat and skin before the bone is separated out. Inevitably, crushing of the material leads to changes in the chemical, physical, sensory and functional properties of the meat, and meat colour is a case in point. This is one of the most important meat-quality characteristics, with a strong influence on consumer acceptance of the retail product.
Groves and Knight refer to EU Regulation (EC) No 853/2004 which defines “mechanically separated meat (MSM) as the product from mechanical separation of residual flesh from bones where there has been loss or modification of the muscle fibre structure. MSM cannot count towards the meat content of products for the purposes of Quantitative Ingredient Declaration (QUID) requirements in EU Food Labelling legislation.”
Today, MDM production take place in two forms. With high pressure and with low pressure. Low pressure MSM was previously called desinewed meat (DSM or 3mm meat) in the UK and it was shown that it has a considerable amount of intact muscle fibre structure similar to some meat preparations (made from hand deboned meat or HDM) and was very different to high pressure MSM. Based on this research and analytical evidence in the literature, DSM was considered in the UK to fall within the definition of ‘meat preparations’ in EU food law rather than that of MSM. By itself, this shows the major difference between High Pressure and Low Pressure MDM.
Groves and Knight reported that “an audit by the Food and Veterinary Office of the European Commission (FVO) was conducted in March 2012 and led to a change in UK policy to align with the Commission’s interpretation that DSM was treated in all respects as MSM, including for the purposes of QUID. This has significant economic implications as the value of the low pressure MSM is considerably reduced. It is accepted that there is no evidence of any increased food safety risks associated with low pressure MSM (DSM).” It is this classification change that I refer to my own England experience in 2012 and is my case in point of focus for the international MDM trade and opportunities created by a change in legislation.
Regulation (EC) No. 853/2004 further defines different rules for MSM produced by techniques that do not alter the structure of the bones and those that do. This is based on whether the product has a calcium content that is not significantly higher than that of minced meat, for which a limit is set down in Regulation (EC) No. 2074/2005. Calcium content is therefore a method of determining if high or low pressure meat recovery is used as opposed to the health issue, which was the case, early on in its introduction on the world stage.
Their report is very educational in terms of various production methods and serves as an excellent introduction into our study. An evidence-based review MSM vs DMS For now, it is enough to identify two main classes of equipment for producing MDM, High Pressure MDM and Low Pressure MDM machines. Even though Abdullah and Al‐Najdawi (2005) do not say if the MDM used in their study was produced with HP or LP, my guess is that it is Low Pressure MDM produced in Jordan. I mailed the author to get clarity on the point since it will have a direct impact on the points of application. For now, I will assume that Low Pressure was used.
Viuda-Martos (2012), generalises more in their definition of these products. Like many authors, they see mechanically deboned meat (MDM), mechanically recovered meat (MRM) or mechanically separated meat (MSM) as synonyms to mark 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 (Püssa and others 2009). They state that the deboning process can be applied to whole carcasses, necks, backs and, in particular, to residual meat left on the bones after the completion of manual deboning operations.
Importantly, they highlight some of the key challenges with this class of products in that the mechanical process of removing meat from the bone causes cell breakage, protein denaturation and an increase in lipids and haem groups and poorer mechanical properties. MDM is therefore characterised by a pasty texture of various consistencies, depending on a wide range of factors. The past texture is generally due to the high proportion of pulverised muscle fibre residue, and the presence of a significant quantity of partly destructured muscle fibres. The term used by these and other authors for this loss or modification of muscle fibre structure is ‘‘destructuration”. Recovered meat is generally considered to be of poor nutritional and microbiological quality and is strictly regulated in its use as a binding agent or as a source of meat proteins in minced meat products. (Viuda-Martos, 2012)
MDM is, therefore, used in the formulation of comminuted meat products and in the creation of fine emulsion sausages due to its fine consistency and relatively low cost. It is an important raw material in underdeveloped countries, due to its price. (Viuda-Martos, 2012) Groves and Knight remind us how important the naming of a substance is and how difficult it is in the case of this class of products. It would be a mistake to see MDM, MRM, MSM or any of the other synonyms as homogeneous product names and that without delving into the details of its production, we cannot fully know its functional qualities. Each individual product, from each different supplier, at different times (depending on input raw material, which is never consistent), must be looked at carefully and evaluated on its own.
There are, however, general observations that can be made related to the overall product class. If nothing else, what follows will give us a list of questions to ask and reasons why it is important. It will further give us an appreciation of the complexity of its evaluation and manipulation and the impact it can have on the final product produced from it.
Poultry MDM Stability
In general, poultry MDM has been shown to have more constant composition compared with pork, veal and beef MDM. Considerable variations in fat and protein content occur in poultry MDM. The amount of back, wing, neck, rack, skin (or no skin) or the ratio of starting material used and type of deboning machine and settings play a major part in final product composition. Deboner head pressure was increased x 3 to increase the yield from 45 to 82%; fat content significantly reduced and moisture content increased. (Hudson, 1994) This is an interesting observation. What could have caused the decrease in fat and increase in moisture? The decrease in fat was probably due to an increase in other components such as connective tissue and the increase in moisture probably refers to unbound water, which resulted as a result of the higher pressure and bone marrow. The addition of bone marrow under higher pressure was therefore less than the increase of connective tissues.
Rancidity problems stem from the method of production. Air with increased iron because of bone marrow are the major reasons. Additional fat stems from bone marrow and skin. Phospholipid fraction, as a percentage of total lipid content, is only at about 1 – 2% in poultry MRM. Over 60% of this may be unsaturated, oleic, linoleic, arachidonic acid. These acids decrease in concentration during freezing or frozen storage of turkey meats or nuggets made from chicken MDM. This (the decrease in polyunsaturated fatty acids) may be explained by reports that chicken muscle homogenates to contain enzymes capable of oxidizing both linoleic and arachidonic acids and one was found to be stable during frozen storage, being 15-lipoxygenase. (Hudson, 1994)
Iron in MDM acts as a catalyst in lipid oxidation is well known, but -> is it haem or non heam iron that plays the dominant role in poultry? Lee et al. say that haem protein, (50% of total iron) is the dominant catalyst for lipid oxidation in poultry MDM. Igene et al. claim that “warmed over flavour” of cooked chicken meat (whole muscle) is due to non-haem iron release during heating, which is the catalyst for oxidation. Kanner et al. say that one reason why haem protein effects lipid oxidation only after heating was that catalase activity was inhibited and this allowed H2O2-activated mayoglobin to initiate peroxidation. Related to uncooked meat, these authors report an iron-redox cycle initiated peroxidation and the soluble fraction of turkey muscle contained reducing substances which stimulated the reaction. Free iron in white and red meats of chicken and turkey increases in concentration with storage time and is capable of catalyzing lipid oxidation. (Hudson, 1994)
Decker and Schanus used gel formation to separate an extract of chicken leg muscle into three protein fractions. One catalysed over 92% of the observed total linoleate oxidation. Iron-exchange chromatography of this active fraction revealed three proteins capable of oxidising linoleate. Haemoglobin was responsible for 30% of total oxidation while two components (according to Soret absorbance) were non-heam proteins and responsible for 60%. (Hudson, 1994)
“Metal ions from the deboning machinery itself and calcium and phosphorus ions from bone may act as catalysts for haem oxidation (Field, 1988).” Also, mechanical deboning of material containing skin leads to a release of subcutaneous fat that tends to dilute the haem pigments present, producing meat of a lighter colour. The same is true for fat released from bone marrow during crushing.” (Abdullah and Al‐Najdawi, 2005)
Related to the effect of the production process on myoglobin, it has been proved that manufacturing MDM “has no effect on the myoglobin contents, although it may influence the form of that pigment, thereby causing colour changes (Froning, 1981).” (Abdullah and Al‐Najdawi, 2005) Much work in this area remains.
Modification of Poultry MDM and Functional Characteristics
-> Texturing
The paste-like nature of poultry MDM limits its use. Early investigations focused on ways to “texturise” it. This can be done by adding plant protein or by various heat treatments. Sensory properties are not always what is desired. (Hudson, 1994)
One method of producing MDM products is to use a twin-screw extrusion cooker. (Extrusion Cooking) Treatment of poultry MDM alone gives unsatisfactory results. The fat content of the material is too high. Satisfactory products similar to meat loaf or luncheon meat were achieved if, as binding or gelling agents, cereal flours, corn starch, egg white concentrate or soy protein isolate were combined with the MDM. (Hudson, 1994) This begs the question as to the gelling temperature of these products.
Alvarez et al. found that chicken extruded with 10 or 15% corn starch, lipid oxidation decreased as extrusion temperature rose from 71 to 115.5 deg C. They suggest that antioxidants were produced with increasing temperature. Hsieh et al. reported that a mixture of turkey MDM (40 parts) and corn flour (60 parts) increased in susceptibility to lipid oxidation above 110°C. The antioxidant BHA (butylated hydroxyanisole) was added to the raw materials before extrusion. (Hudson, 1994)
-> Haem Removal
Haem pigments in the product impacts on product stability and in poultry MDM it has a tendency to create a dark colour in the final products. Much effort is expended to remove these pigments and so extend the range of products in which the MDM may be used. (Hudson, 1994)
Froning and Johnson showed that centrifuging poultry MDM would remove haem pigments. Washing procedures was first developed in Japan to remove haem proteins, enzymes and fats from fish during the production of the myofibrillar protein concentrate, surimi. A lot of work has been done to extend the same procedure to washing MDM. However, there are several reasons why surimi technology might not be applied directly to poultry MRM, viz:
1. Surimi is prepared from whole muscle while poultry MDM is isolated from bones after most muscle tissue is removed.
2. Poultry MDM can have considerable quantities of connective tissue in the final product, e.g. histochemical investigations have shown the connective tissue: muscle ratio of chicken MRM to be 1 : 1.2.
3. Fish mince is frequently washed during preparation, but water washing is not an efficient means of removing haem pigments from MRM.
4. Lee suggested the size of perforations in the deboner drum of fish deboners ranges from 1 to 5 mm, with orifices of 3 to 4 mm giving the best quality and yield of surimi. Poultry deboners seem to have a pore size below 1 mm and thus the particle size of the products will differ. Since the term ‘surimi’ has long been associated with the product isolated from fish muscle, it is perhaps debatable as to whether the term should be applied to the material prepared from poultry MRM.
(Hudson, 1994)
Other terms used are:
‘Washed mechanically deboned chicken meat’, ‘myofibrillar protein isolate’, (MPI), ‘isolate of myofibrillar protein, (IMP). The acronym IMP is problematic since it is widely accepted as an abbreviation for inosine monophosphate. Clearly some rationalization of nomenclature is required and perhaps a term such as ‘poultry myofibrillar protein extract’ would be more appropriate. (Hudson, 1994)
One of the earliest studies of poultry, turkey neck MDM, considered to be the darkest poultry MDM, was washed either three times in water or once in 0.04 M phosphate at various pH values, followed by two water washes. Then, the mixtures were pressed through cheesecloth to remove as much moisture as possible. The yield of paste from water-washed MRM was higher than that which had been treated with phosphate, but it had a darker colour. The researchers concluded that washing with 0.04 M phosphate at pH 8.0 provided the most efficient means of removing red pigment from turkey MDM. Froning and Niemann reported that extraction of chicken MDM with 0.1 M NaCI significantly reduced fat concentration and colour, and increased protein concentration. Others, using different washing techniques, particularly the use of bicarbonate as the washing medium, have found that either the protein content of the washed material was similar to that of the starting material, or was up to 7% lower. However, all agreed that washing drastically reduced the fat level of the recovered material. (Hudson, 1994)
Washing with bicarbonate appears to be the most efficient way of removing pigment from poultry MDM, probably due to the fact that the pH value of the slurry makes the blood proteins more soluble, there may be other factors at work to influence the final colour of the washed product. For example, Trziszka et al. found that if, following bicarbonate extraction, water washing was carried out at pH 5.5, the product was lighter than at pH 6.0, while the variable amounts of connective tissue present in the washed residue can influence the appearance of the material, as shown by Kijowski et al., who found that removal of connective tissue by sieving increased both the darkness and redness of water-washed chicken MRM. (Hudson, 1994)
The yield after washing range was 13.5 to over 62% of the starting material. Reasons for this variety may be the result of a number of factors such as source material for MRM, grinding of MRM before washing, nature of washing medium, washing time, adjustment of pH, number of washes, ratio of MDM to extractant and centrifugal force applied during separation of ‘meat’ and extractant. (Hudson, 1994)
Cryoprotectants, such as mixtures of sugars and/or phosphates, must be added for the washed material to retain its gelling and water-holding abilities during frozen storage. Washing improved the functional properties of the material – after cooking the washed MDM was more chewy, less cohesive and had increased stress values but the cooking losses from washed material were higher, probably due to the fact that ‘free’ water was absorbed during washing. The best indication of the success of the washing procedure is probably in practical terms measured by the performance of the myofibrillar complex in products. There have been a few studies who looked at this. Frozen-thawed, bicarbonate washed turkey MDM at a level of 10% reduced the fat level of frankfurters, while increasing the expressible moisture content and resistance to shear compared with control frankfurters. Scanning electron microscopy did not reveal any obvious structural differences between controls and frankfurters containing 10% washed MDM. Hernandez et al. reported – the protein paste from washed turkey MDM could be incorporated into patties at levels up to 20% without adversely affecting sensory quality. Trziszka et al. reported that up to 50% of the ground chicken meat in hamburgers could be replaced by carbonate-washed turkey MRM without reducing the acceptability of the product. A sensory panel gave slightly lower flavour scores to hamburgers containing the protein extract, although whether this was due to the ‘soapy’ taste reported by Dawson et al. is not clear. (Hudson, 1994)
-> Improving Emulsification and Gelation
“Since MDM is used in the manufacture of emulsion products, emulsifying capacity (EC) is an important property of the raw material (Froning, 1981; Field, 1988). EC has been defined as the amount of oil that can be emulsified by the material prior to the reversion or collapse of the emulsion (Swift et al., 1961; Ivey et al., 1970; Kato et al. , 1985). Factors affecting the emulsifying properties of a protein are: protein concentration, medium pH, oil temperature, mechanical force and rate of oil-addition during emulsification “(Galluzzo & Regenstein, 1978; Wang & Zayas, 1992; Zorba et al., 1993 as quoted by Abdullah and Al‐Najdawi, 2005.
Although the protein complex isolated from washed MDM could be of use in altering textural properties of poultry products, further possibilities of effecting such changes exist. For instance, Smith and Brekke found that limited acid proteolysis improved the emulsifying capacity of actomyosin isolated from fowl MDM, as well as improving the quality of heat-set gels. Kurth used a model system to demonstrate the crosslinking of myosin and casein by a Ca-dependent acyltransfer reaction catalysed by transglutaminase (EC 2.3.2.13; R-glutaminyl peptide amine gamma-glutamyl transferase). Application of the technique to actomyosin prepared from turkey MDM showed that actin did not polymerize, but that the disappearance of myosin monomer was accompanied by a concomitant increase in polymer content and that the gel strength of enzyme-treated protein was greater. The polymerization could occur at temperatures as low as 4°C, thus opening up possibilities for the manufacture of new products. (Hudson, 1994)
Emulsifying capacity
“Mean EC values are presented in Table 1 and show significantly higher values for both kinds of deboned meat without skin (treatment 2: manual deboning of skinned carcasses; treatment 4: mechanical deboning of skinned carcasses.). The presence of skin in MDM is considered detrimental to EC, because of its collagen content, and this view is supported by the significantly lower EC value obtained for MDM prepared from whole carcases (treatment 3: mechanical deboning of whole carcasses), in comparison with that from skinned carcasses (treatment 4: mechanical deboning of skinned carcasses). Deboning of skinned carcasses by hand (Treatment 2: manual deboning of skinned carcasses) significantly increased the proportion of insoluble protein in the meat (Table 1), which can have an adverse effect on EC. However, this would be counterbalanced, to some extent, by the relatively low pH of the material that would increase protein solubility. Increased levels of insoluble protein could lead to protein enveloping the added oil droplets, thereby reducing the total amount of oil that is available to be emulsified (Swift, et al., 1961). The concentration of protein is also critical in relation to its own stability. When the concentration is sufficiently low, the protein structure unfolds to a degree that favours stability (Ivey et al., 1970).” (Abdullah and Al‐Najdawi, 2005)
“It is clear from Table 2, that EC values increased significantly during frozen storage of manually deboned meat, but declined in the case of MDM obtained from skinned carcasses (Treatment 4: mechanical deboning of skinned carcasses). These changes occurred exclusively during months 1 and 2, with no significant effect subsequently for any treatment group. The initial decline in EC values for Treatment 4 may be attributable to the partial denaturation of protein. Accordingly, the corresponding increase in EC for manually-deboned meat is likely to reflect the absence of any mechanical damage to the structure of the meat. In this state, the protein would remain largely intact.” (Abdullah and Al‐Najdawi, 2005)
Poultry MDM: Water Holding Capacity
“Another important property of meat used for product manufacture is water-holding capacity (WHC). Like other meats, poultry contains approximately 70% water in the raw state, much of which is not tightly bound and is known as ‘free water’ (Baker & Bruce, 1989). The WHC of muscle foods has been used as an index of palatability, microbial quality and manufacturing potential (Dagbjartsson & Solberg, 1972). It is highly important in the formulation, processing, cooking and freezing of meat products, because it relates to weight loss and ultimate quality of the finished product (Field, 1988). Factors affecting WHC are pH value, presence of iron, copper, calcium and magnesium from bone, content of skin and collagen, and the processes of cooking and freezing.” (Abdullah and Al‐Najdawi, 2005)
The pH values “obtained from mechanically deboned material (mechanical deboning of whole carcasses and mechanical deboning of skinned carcasses) were significantly higher than the values for manually-deboned meat (manual deboning of whole carcasses and manual deboning of skinned carcasses). This may be explained by the unavoidable incorporation of bone marrow in the MDM, which therefore had a higher pH. Crushing of the bones also would have released mineral substances capable of contributing to the increase in pH (Zorba et al., 1993), as well as raising the protein content and concentration of free amino acids. At higher pH values, protein solubility would be increased, limiting any possible improvement in the functional properties of the meat.” (Abdullah and Al‐Najdawi, 2005)
“There were no significant differences between treatment groups in relation to WHC (Table 3). Thus, neither the presence of skin nor the method of deboning influenced WHC values. The absence of a skin effect is in agreement with Field (1988), and the collagen content of MDM may have been too low. However, while mechanical deboning could have affected WHC, because of the higher pH values obtained (Table 1), this was not the case (cf. Demos & Mandigo, 1995).” (Abdullah and Al‐Najdawi, 2005)
“Table 4 shows that frozen storage only affected the meat from skinned carcasses, whether manually- or mechanically-deboned. WHC values declined significantly over the 3-month period, possibly because of the lower fat content and therefore greater rate of protein denaturation.” (Abdullah and Al‐Najdawi, 2005)
Poultry MDM and Pigment Concentration
“Table 5 shows the differences between the experimental treatments for pigment concentration, which would have included both haemoglobin and myoglobin. It is evident that the mean value was significantly higher for MDM without skin (Treatment 4: mechanical deboning of skinned carcasses) and lowest in meat from manually deboned, whole carcasses (Treatment 1: manual deboning of whole carcasses). Pigment concentrations in meat obtained by either method of deboning were clearly influenced by the presence of skin, and were lower when skin was present, possibly because of a dilution effect. However, differences in this respect between whole and skinned carcasses were less for those that had been deboned mechanically. The higher values obtained are consistent with a release of haemoglobin from bone marrow during mechanical deboning.” (Abdullah and Al‐Najdawi, 2005)
“Meat colour was not measured instrumentally in this study, but some variation in colour was apparent. It may have involved the conversion of myoglobin to oxymyoglobin in MDM and binding of ions from the metal surface of the deboner to the haem pigment (Froning, 1981; Demos & Mandigo, 1995). Possible pH effects in MDM, resulting from the release of bone marrow, could have led to changes in the structure of myofibrillar protein and may have increased the amount of myoglobin extracted. Also, pH is known to be capable of influencing the porphyrin ring-structure of meat pigments through its effect on iron.” (Abdullah and Al‐Najdawi, 2005)
“Changes in pigment concentration during frozen storage are shown in Table 6. Results indicate that pigment levels either remained static or diminished over time. For manually-deboned carcasses, there was a significant decline when skin and its associated fat were absent, but not when skin was present, suggesting a possible protective effect in limiting pigment oxidation (Field, 1988). No such effect was observed for mechanical deboning, where oxidation of pigment would be more likely, because of the release of potentially oxidising substances.” (Abdullah and Al‐Najdawi, 2005)
Poultry MDM: Sensory Evaluation
“Initially, there were no significant differences between treatments with respect to aroma, colour, texture or overall acceptability of the meat, as judged by the sensory panel. After storage for up to 12 weeks (Table 7), aroma values showed little or no change for hand-deboned meat, but MDM from whole carcasses (Treatment 3: mechanical deboning of whole carcasses) showed a significant reduction in score that was indicative of deterioration. This change could be attributed to the higher fat content of the meat and therefore greater susceptibility to oxidation.” (Abdullah and Al‐Najdawi, 2005)
“In relation to meat colour, manually-deboned meat stored for 6 weeks was more acceptable than either kind of MDM, presumably because of the lower haemoglobin content of the former. After 12 weeks, only hand-deboned meat from skinned carcasses (Treatment 2: manual deboning of skinned carcasses) was significantly different and more acceptable to the panel, although the reason for this is unclear.” (Abdullah and Al‐Najdawi, 2005)
“Meat texture was less affected by carcass treatment during storage in the frozen state for 6 weeks, and no significant differences were observed. After 12 weeks, however, significantly lower scores were obtained for both kinds of MDM. Thus, freezing may have further damaged meat structure and the presence of trace amounts of bone (Al-Najdawi & Abdullah, 2002) could have contributed to the lower panel rating. Overall acceptance scores were clearly better for the manually-deboned meat, both at 6 and 12 weeks of frozen storage.” (Abdullah and Al‐Najdawi, 2005)
Conclusion by Abdullah and Al‐Najdawi
“This study has confirmed the role of skin content in deboned meat as a factor affecting EC, but has found no effect of deboning method or incorporating skin on WHC, despite differences between manually- and mechanically-deboned meat with respect to pH. On the other hand, the influence of skin on pigment concentration appears to be mainly a dilution effect. Although higher pigment levels in MDM could be attributed to the release of bone marrow during the deboning process, assessment by a sensory panel showed no differences initially between the experimental treatments in relation to aroma, colour, texture or overall acceptability of the meat. Only after frozen storage for up to 12 weeks, were differences apparent in both functional and sensory properties, and the study has highlighted the superior keeping-quality of manually-deboned poultry meat, according to a sensory assessment.” (Abdullah and Al‐Najdawi, 2005)
Summary
This is a work-in progress. As I expand the functional value of different MDM or related products, I will add it to this document. It is an adventure in discovery!
Reference
Abdullah, B. and Al‐Najdawi, R. (2005), Functional and sensory properties of chicken meat from spent‐hen carcasses deboned manually or mechanically in Jordan. International Journal of Food Science & Technology, 40: 537-543. doi:10.1111/j.1365-2621.2005.00969.
EFSA Panel on Biological Hazards (BIOHAZ). 2013. Scientific Opinion on the public health risks related to mechanically separated meat (MSM) derived from poultry and swine; European Food Safety Authority (EFSA), Parma, Italy; EFSA Journal 2013;11(3) : 3137.
Groves, K and Knight, A. An evidence-based review of the state of knowledge on methods for distinguishing mechanically separated meat (MSM) from desinewed meat (DSM). Food Standards Agency & DEFRA
Hudson, B. J. F. (Editor). 1994. New and Developing Sources of Food Proteins. Springer – Science + Business Media. (Poultry – the versatile food by JM Jones)
Viuda-Martos, M; Fernández-López, J.; Pérez-Álvarez, J. A., Hui, YH (Editor) Mechanical Deboning, January 2012, DOI: 10.1201/b11479-30, In book: Handbook of Meat and Meat Processing, Chapter: Mechanical Deboning, Publisher: CRC Press; Taylor & Francis Inc.