We all like to eat meat that is tender and succulent rather than tough and stringy so what is the best way to tenderize meat? How tender meat is naturally depends on a number of factors including how the meat is treated after the animal is slaughtered, the type of meat and the age of the animal.

Meat has a high proportion of protein in the form of connective tissue, called collagen, which needs to be broken down before it is tender enough to eat. Collagen makes up around 30% of the protein found in animal tissues and is a major component of skin, cartilage, organs, bones and tendons.

What is collagen?

Collagen is a protein that is made from three intertwined poly-peptide chains. A poly peptide chain is a chain of amino acids bonded together to make a natural polymer. It is a stiff, strong structure that is hard to break down. Muscles that are weight bearing or used often contain larger amounts of collagen than other parts of the animal so legs and rump will be high in collagen. The age of an animal also has a bearing on the amount of collagen present which is why meat from older animals is tougher than that from younger ones.

Collagen

What ways are there to tenderize meat?

Hanging - meat can be hung after the animal is slaughtered. This loosens the muscle fibres.
Grinding and pounding - hitting the meat with a mallet is a popular way to tenderize meat, especially steak. The action of pounding on the meat loosens the muscle fibres by breaking up the connective tissue. Mincing or chopping up meat also has the same effect.

Cooking - cooking meat slowly with moist heat breaks down the collagen. However cooking also hardens the muscle fibres so a balance needs to made between gelatinising the collagen and preventing the muscles fibres from hardening. Moist cooking for around three hours is usually enough to break down the collagen but not long enough to harden muscle fibres. The exception to this is cooking some meats, like steak, that do not have a high collagen content. These types of meats are best cooked quickly with a dry heat as they will become tough if cooked slowly. Some meats can also be tenderized more easily in a pressure cooker. Gelatin is the product when collagen is broken down by heat.

Marinating - meat can be marinated in alcohol and acidic fruits or vinegar to tenderize it. Marinating is also used to add flavour to the meat. Marinating takes time for the ingredients to break down the connective tissue in the meat. Alcohol is effective but acids from vinegar or fruits works even better.

Using enzymes to tenderize meat - some foods contain enzymes that can be used to tenderize meat. Papaya (Paw-paw) contains the enzyme papain and pineapple contains bromelin both of which break down the collagen in meat. As we said earlier collagen is made up of three protein chains and these enzymes can break the bonds between the amino acids in the protein chains.

Individual amino acids in the protein are joined together with a peptide bond (coloured blue in the protein fragment pictured below). It is this bond that these enzymes break, thus fragmenting the protein chains and destroying the collagen structure.

Protein fragment showing peptide bond (in blue)

Conclusion

Chemistry in everyday life is a fascinating subject! Look around you and you can see examples of how chemistry comes into almost everything you do every day. I hope this has sparked an interest in this subject and that you will be eager to learn more.

Image Credits

Collagen by Nevit

papaya by Olegivvitby

Cast Iron Cooking by LarimdaMEMeat