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A Critical Control Point approach to beef eating quality
Meat technology update 99/1 – February 1999 Reprinted November 2006 A Critical Control Point approach to beef eating quality The production of beef that satisfies or, Tenderness/toughness better still, exceeds the consumer’s The variation in tenderness/toughness expectations with regard to eating quality can be partitioned into the muscle-fibre is central to the industry’s future. and connective-tissue components. In The purpose of this update is to provide living muscle, the fibres are responsible an overview of beef eating quality and for contraction. The action of the the critical control points in any contraction is then transferred through production pathway that can impact on the connective tissue framework of the quality. muscle to the ligaments and tendons which attach to the skeleton. After death, Eating quality muscle-fibre contraction and relaxation Eating quality is determined by the continues until the biochemical reactions consumer’s perception of whether the underpinning this process cease. At this product was: point, the fibres are irreversibly bound. This loss of extensibility is referred to as 1. Tender or tough rigor. The degree of muscle-fibre 2. Juicy or dry shortening that occurs after death is the most important factor governing overall 3. Flavoursome or lacking in flavour tenderness/toughness in cuts low in and free from taints. connective tissue (e.g. striploin). This, in Most of the research effort has been turn, is regulated by the rates of pH dedicated to the improvement of beef decline and cooling in the muscle. The tenderness, as consumers have clearly indicative relationships between pH and said that the variation in tenderness/ temperature decline and the degree of toughness is the major factor limiting shortening are shown in Table 1. eating quality. In the future, as the Another process that impinges on the variation in toughness is successfully magnitude of muscle-fibre toughness is reduced, it is anticipated that issues such the enzymatic breakdown of some of the as flavour will take on greater muscle-fibre proteins, which occurs when prominence. meat is aged. This is referred to as proteolysis and is controlled by a number of enzyme systems. Of these, the calcium-dependent calpains and their inhibitor, calpastatin, and the lysosomal cathepsins are considered the most important. TABLE 1: Indicative relationships between pH and temperature decline on post-mortem muscle-fibre contraction pH Temperature Percentage of Effect °C shortening# ≤6.0 12-20 10-20 Optimal for tenderness >6.0 (slow) <12 (fast) 30-50 Extremely tough (cold shortened) <5.9 (fast) >30 (slow) 20-30 Some loss in tenderness and possibly juiciness (heat shortened) # Relative to approximate resting length The contribution of connective tissue to Since complete coverage is not possible in overall toughness depends on both its this update, only a brief overview is given. quantity and quality. The amount of More detailed discussion of pre-slaughter connective tissue varies between muscles management of cattle and post-slaughter best and this is a reflection of muscle function. For practice will be the subjects of future updates. instance, muscles involved in movement contain higher amounts of connective tissue Pre-slaughter stress must be minimised than muscles used to maintain posture. during the marketing of animals to slaughter. Connective tissue toughness occurs in Stress results in losses in muscle glycogen. proportion to the presence of heat-stable Sustained stress and/or muscular activity crosslinks within the connective tissue. Since which results in the loss of >30% of the the proportion of crosslinks increases with glycogen reserves in a normal, healthy animal age, so does the connective tissue toughness. will result in meat with a higher ultimate pH (≥5.9), increased toughness and reduced Critical Control Points shelf life. This meat is typically referred to as ‘dark, firm and dry’ (DFD). To deliver beef of consistent eating quality, it is important to recognise that tenderness can There is new evidence which suggests that be influenced at any point along the acute stress immediately pre-slaughter or production pathway right up to and including stress of a more subtle nature could be the final process of cooking. In view of this, implicated in altering the rates of post-mortem the Meat Standards Australia (MSA) system pH decline and proteolysis. This area is has targeted critical control points within currently being investigated by the production pathways and implemented Cooperative Research Centre (CRC) for the specifications or practices which ensure that Cattle and Beef Industry (Meat Quality) and losses in eating quality are minimised. positive results have been achieved already by varying pre-slaughter management The critical control points, key factors within strategies. each, and the association or effect they can have on the intrinsic muscle attributes are Post-slaughter best practice is targeted at presented in Table 2. both minimising the degree of muscle-fibre contraction and ensuring optimal activity of Pre- and post-slaughter factors the proteolytic enzymes. Minimising the The management of the animals and their degree of shortening can be achieved by carcasses in the 24–48 hours immediately ensuring the muscle enters rigor at an optimal prior to and after death has the greatest pH and temperature (refer Table 1) or by influence on ultimate eating quality. restricting the fibres from shortening by Inappropriate management during this phase stretching or restraining the muscle. The rate can result in irreversible losses in eating and extent of pH and temperature decline also quality. influences post-mortem proteolysis. However, the nature of this relationship is less clear and is the subject of current investigations. TABLE 2: Critical control points and associations with muscle characteristics Critical Factor Tenderness Juiciness Flavour Control Muscle Ultimate Rate of Rate and Connective Point fibre pH pH extent of tissue shortening (normal decline proteolysis contribution ≤5.7) On-farm Breed ? ?* Environment/nutrition ? * Age/weight at ? ? * slaughter Pre- Method of marketing ? ? slaughter Time off feed ? ? Lairage management ? ? ? Weather conditions (extremes) Slaughter Stunning Electrical inputs# ? Method of carcass hanging Duration prior to chilling Rate of chilling Process- Ageing ? ing Cooking method/ duration # ‘Electrical inputs’ includes electrical stimulation, immobilisation, and stiffening during hide pulling * The association between on-farm factors and flavour is primarily related to the amount, distribution and com- position of fat within the meat Some influence Moderate influence High influence ? No conclusive evidence, but intuitively, it is reasonable to suggest an association. With respect to minimising muscle-fibre 3. Effective chiller management (achieve shortening, the processor has three basic a moderate rate of cooling; however, options: this is not always practical from a food safety point of view). 1. Apply electrical inputs such as stimulation in conjunction with rapid The full benefits of either electrical inputs or chilling, immobilisation which may be alternative hanging treatments will be carried out after stunning, and stiffening realised only when they are used in during downward hide pulling. These conjunction with fast chilling rates. Electrical inputs accelerate pH decline and must stimulation may not always be appropriate be carefully monitored. for heavy carcasses. 2. Use alternative carcass hanging treatments (prevents the myofibrils from On-farm factors contracting), e.g. The primary on-farm factors include: • Tenderstretch (refer Meat Technology Update 98/2) 1. Breed • Tendercut® 2. Weight and age at slaughter 3. Nutrition/production system. vacuum-packaged cuts at storage temperatures of 0-2°C, improves meat Of all the critical control points, the on-farm tenderness. The magnitude and rate of factors have provoked, and continue to improvement will depend on the post- provoke, the greatest amount of slaughter management of the carcasses, controversy. Unfortunately, much of the the storage temperature and the ageing debate has been unnecessary, as the duration. For example, tenderness magnitude of any effect has often been improvements following ageing will be overestimated because the post-slaughter smaller in magnitude following effective conditions were not controlled. For example, electrical stimulation and/or tenderstretching differences in weight and fatness, which compared with normally hung, non- typically occur between breeds (e.g. early stimulated beef. The longer beef is aged, versus late maturing breeds), and different the larger the improvement; however, the finishing systems (e.g. feedlot versus majority of change occurs within the first pasture finishing) will give rise to differences seven days after slaughter. Ageing meat at in carcass cooling rates. In the absence of higher temperatures will also increase the electrical inputs or alternative hanging rate of improvement; this may, however, treatments and when rapid chilling is used, also compromise shelf life, flavour and these differences in cooling rates will cause weep. variation in the degree of muscle-fibre contraction and thus, tenderness. Cooking is the final act in the process and it can have the largest effect on eating quality. CRC and MSA results have demonstrated Over-cooking or mismatching of the cut with that, once the post-slaughter variation in the appropriate cooking method can result eating quality has been controlled, any in significant consumer dissatisfaction. breed effect is quite small. That said, there Consumer education is one way in which are noticeable breed effects in tenderness the chance of failure in the household can and these are most evident when the Bos be avoided. Against this, however, is the indicus content exceeds 75%. The exact issue of ‘convenience culture’ which reasons for this are linked to a number of distinguishes the modern-day consumer. intrinsic muscle factors; however, reduced Consumers not only lack the traditional proteolysis (i.e. ageing potential) has been meat preparation skills but, more demonstrated as a primary mechanism. importantly, they lack the time to prepare meals. Unfortunately, it is unlikely that this The age of an animal at slaughter is will change in the near future. particularly important in the context of connective tissue toughness. Currently, This represents an opportunity for the MSA require that all eligible cattle are less Australian beef industry through the than 30 months of age. MSA have also application of value adding. The adoption of developed a specification, defined as value adding technologies will enable the ‘weight at maturity’ (WAM), which is a crude production of a wide range of pre-prepared, estimate of the growth rate/path. flavour-enhanced, ready-to-eat beef meal solutions. Benefits associated with this With regard to beef flavour, on-farm factors approach include the delivery of: are also important. Decisions that influence either the feed type (e.g. pasture species 1. Consistent eating quality and grain ration content) and/or carcass fatness (amount and composition) impact 2. Convenient beef products which match on beef flavour. the tastes and health requirements of consumers Other processing factors 3. Ultimately, more competitive beef Ageing meat, either ‘on the bone’ or as products. This concept underpins the next stage for MSA, which aims at grading and labelling cuts in ways which reflect their end use. This not only expands the application of MSA to more than just the high value primal cuts (e.g. striploin, cube roll, tenderloin and rump), but it will ultimately obviate the need for some of the current pathway specifications, particularly the on-farm factors. For example, issues such as breed and growth history are not likely to have a large effect if the primal cut is to be minced, blended, flavour enhanced and pre-cooked prior to retailing. Contact us for additional information Meat Industry Services is supported by the Australian Meat Processor Corporation (AMPC) and Meat & Livestock Australia (MLA). 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"A Critical Control Point approach to beef eating quality"