BIOLOGY Volume 2 - A Guide to General Biology - 2004

12. MICROBIOLOGY AND BIOTECHNOLOGY

12.16. Enzyme technology

12.16.5. Meat tenderisation

Meat consists mainly of Muscle protein. Muscles are made up of bundles of protein fibres grouped into blocks surrounded by Connective Tissue. Connective tissue also contains structural Proteins, notably Collagen and Elastin. Collagen forms tough, inelastic white fibres, while elastin forms elastic yellow fibres. Meat can be made easier to chew—in other words, more tender—by pre-treating it to break down some of the connective tissue proteins and muscle fibres. This shortens the fibres, allowing them to separate more easily and thus making the meat more tender.

Protein-digesting Enzymes are called proteinases, and Papain is the enzyme most commonly used for meat tenderisation. It is extracted from the juice of the papaya plant. Commercial meat tenderisers containing this enzyme are readily available for home use. Meat should be left to marinate in the juice for some time before cooking to allow the enzymes to work, as cooking causes them to denature. In some countries, though not in the UK, papain is injected into the bloodstream of animals immediately before or after slaughter to ensure tenderisation.

Similar tenderisation processes occur naturally in meat after death. As Cells die, Lysosomes break down and release their enzymes, which initiate the breakdown process. This process is known as autolysis (fig. 5.10.6). For this reason, meat carcasses are hung in cold storage for a few days prior to use.