Factors affecting Flavour and Texture of Meats Before and After Slaughter
Lipid oxidation is one of the main causative factors in the meat deterioration. At the initial stage of the oxidation, lipid hydroperoxides are formed before the development of the secondary oxidation. The secondary oxidation is mainly responsible for the off-flavour production in meats. Studies have shown that the meats from supplemented animals usually exhibit no lipid oxidation in muscle and adipose tissues. The supplementation of vitamin E to live animals can considerably inhibit lipid oxidation.
The presence or absence of lipid oxidation is determined by thiobarbituric acid (TBA). TBA can be directly applied on meats. Alternatively, the assay is performed on aliquot acid extracted from meats or on specific amount of meat sample in the steam distillate form. Furthermore, hexanal concentration (carbonyl groups) can be determined to assess the oxidative condition in the muscle. In fact, hexanal and other carbonyl-based compounds are analysed as indicators of auto-oxidation of fatty acids.
Meat is likely to be unpleasantly tough in response to the muscle contraction during the post-mortem. There have been many practical efforts to decrease the toughness of meats including the control of the post-mortem glycolytic action. Pressure treatment of post-mortem glycolysis can generally improve the structural integrity and stability in the meat composition. However, it has the disadvantage of requiring heat treatment of meat to about 60ºC and consequently the meat will appear like cooked meat as opposed to the fresh looking raw meat.
Enzymatic tenderiser has also been developed to improve the texture of meats. It is based on the application of certain enzymes (with tenderising functions) to the meat cuts. The enzyme can be applied into the tissue of the meat using a specific method to ensure that the meat is uniformly tenderised. Alternatively, enzyme-based solution can be infused into the large blood vessels of the meat.
However, the optimum strategy for tenderising the meat is the injection of enzymes to the live animals before slaughtering to ensure the even distribution of enzymes in animals body develops with maximum deep penetration into the tissue. The injected enzyme can then be activated in the end products by the heat treatment during the cooking (resulting in acceptable tender meats for the consumption).