Meat quality varies because it is affected by many factors in the animal, such as fatness and diet and the changes that are introduced during processing.
One important aspect, which is still not fully understood, is how the way the animal is treated before slaughter affects quality. Animals that are well-treated and slaughtered in premises that allow them to remain calm will have better overall quality than those which become excited or stressed. Why is this?
If animals are put under stress, the stress hormones cause the carbohydrate stores in muscle (glycogen) to be broken down into sugars for use as energy. If too much glycogen is used up, there isn't enough for the proper formation of lactic acid which occurs in the period after slaughter and which is so vital for consistent meat quality. The colour becomes dark and the surface appears dense as the turgid muscle fibres become tightly packed together. This dark meat has poor shelf-life because the low acid conditions favour bacterial growth. Also, the meat is likely to be tough because the enzymes, which break down the fibrous structure of muscle during tenderisation, work less efficiently. Prevention of these consequences of animal stress lies in proper handling of the animal before slaughter, in transport, in the lairage and at stunning.
There has been a lot of research on these topics in the UK and the findings have been widely taken up by industry. An outstanding question is the ideal time spent in lairage. Is a period of recovery from transportation needed and how long should it be? I believe the evidence shows that short lairage times are best, allowing animals to settle down after transportation, but not allowing them to become fractious in the new and strange environment. So two to four hours for beef cattle is better than 10 hours.
27 October, 2016, 8:30
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