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"What is the exact difference between tough and tender meat?"

Hi there,

I just discovered your site and I very much like it! As a biologist and amateur cook I am always interested in the place where science and enjoyment meet! My question is about tenderness: what is the exact difference between tough and tender meat? Thanks in advance and keep up your nice cooking site!

Dr. Klaus Bendrat


Still have more questions? You'll find more answers in our archived monthly feature articles by the Inquisitive Cooks.

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Dear Klaus,

Thanks for the good question about the tenderness and toughness in meat. Tenderness starts with the age of the animal, and the amount of exercise it receives. As an animal gets older, and if it's allowed to graze, it receives more exercise. Therefore, its muscles are more developed (and tougher). Working muscles however, also accumulate flavor extractives in the muscle fibers. So less tender cuts cooked with care are also very tasty.

Your question also provides the opportunity to mention to readers the special "Meat" section also on this site. There's lots to learn from the information posted there.

With reference to a close-up look on tenderness, all meat is composed of muscle fibers, connective tissue, fat, and bone. One of the major influences on tenderness is connective tissue.

The two types of connective tissue we hear about most often are collagen and elastin. Collagen surrounds individual muscle fibers, as well as uniting bundles of muscle fibers that make up the muscles themselves. Collagenous connective tissue is also found in the tendons that attach muscle to bone, as well as the skin and the bones. So, collagen predominates over elastin in most cuts of meat, except for some muscles in the round, the chuck (or shoulder area), and some cuts from the legs. You can usually distinguish the type of tissue by color. Collagenous connective tissue appears pearly white, while connective tissue in which elastin predominates is yellowish and is usually removed by the butcher.

The relevance of connective tissue to cooking is that collagen dissolves in hot water, so less tender cuts where connective tissue is well developed benefit from cooking with moisture. In contrast, fibers of elastin are not tenderized by moist heat, and therefore remain tough. In mature, well-exercised animals, connective tissue is considered a major contributor to toughness. Therefore, the quality of meat, where the cut comes from on the carcass, and the cooking method all influence tenderness.

In meat from younger animals with little-exercised muscles, tenderness is strongly affected by how the carcass is handled before being purchased by the consumer. About 24 hours after slaughter, the muscles become rigid and stretch less easily in a process called rigor.

Cross-links form between components in the filaments of the muscle fibers and become locked in place. This is why aging is important, for given sufficient time muscles regain their pliability. Aging is accomplished in various ways. It's also a complex process in terms of the changes that occur, and how quickly they take place. However, it does improve tenderness.

We hope you'll continue to visit this site and check out the discussion forum. As you're both an amateur cook and a biologist, you can likely add information from a different perspective. That's what makes a lively discussion!

Anne and Sue



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