Critical control points for meat quality in the Australian sheep meat supply chain

Abstract

The sheep meat eating quality research program has identified a number of outcomes and critical control points in the supply chain from live sheep genetics to cooked meat. The critical control points, which are largely independent of each other, can be translated into quality management systems to increase average eating quality of all cuts and lower variability. The choice of sire was a critical control point in that selecting for high growth rate and muscling can adversely affect eating quality. The challenge is to make sure that high yield traits are not promoted at the expense of eating quality. Animal age was a critical control point but it was clear that the definition of hogget could be revised to include slightly older animals with teeth in eruption but not in wear. Moreover, M. longissumus dorsi from older animals had only slightly lower eating quality than that from lamb such that this cut could be positioned as a premium product at all maturities, complementing the universally tender muscle psoas major. There was no doubt, however, that over all muscles, lamb remained the premium product. The critical control point for nutrition is that it be adequate, typically to ensure growth of at least 50 g/animal.day. Meat quality is improved through higher glycogen concentrations in muscles at slaughter, higher intramuscular fat content, and possibly reduced collagen crosslinking. Critical control points between muster and slaughter are more difficult to define but are generally aimed at stress reduction to minimise occurrence of the high ultimate pH condition. They include avoiding temperature extremes, loud noises and use of dogs, implementation of good lairage design and the use of skilled animal handlers. Stress is best monitored by ultimate pH measurements in abattoirs, rather than at remote points down the supply chain. After slaughter, the use of electrical stimulation to accelerate post mortem glycolysis is a critical control point. Its use is indicated where 2 conditions are simultaneously met: carcasses are Achilleshung throughout processing, and the meat is destined for early consumption, as would normally be the case for the domestic market. By accelerating glycolysis, the temperature at rigor can be optimised for rapid tenderisation of low-connective tissue muscles through ageing. The alternative to electrical stimulation of these muscles for the local market is Tenderstretch hanging where rapid ageing is less temperature dependent. Where electrical stimulation is applied the monitoring of its effects with a temperature probe and a pH metre is a critical control point. Even where stimulation is not applied, measurement of average muscle temperature and pH is useful for defining any process. This is because the first 24 h after slaughter sets the scene for later meat storage/distribution, which has its own critical control point: the temperature at which meat is held between abattoir and consumption. Where meat is destined for early sale, the temperature of processing and storage can and should be higher than where the meat is destined for long-term storage as in export markets. For early sale, rapid ageing to optimum eating quality is promoted by higher temperature (2-4°C), whereas for export sale, very cool meat will slowly age in the weeks before consumption while at the same time minimising spoilage and maximising display life. Thus, matching the time-temperature profile of processing and storage to a particular market is a critical control point. The retail end of the supply chain has its own control points, principally display temperature and choice of display packaging, which have major effects on chilled display life. The cooler the better. Compared with conventional overwrap packs, modified atmosphere packs extend display life by typically 80%. However, these more sophisticated packs cost more and will not suit all domestic retailers. The matching of muscles by age with recommended cooking method is a critical control point at retail for ensuring consumer satisfaction. The challenge is effective communication with consumers and is part of the wider challenge of effectively communicating quality-related information at all links of the supply chain. © CSIRO 2005.