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Wednesday, Aug 27, 2014
Lifestyle Stories

Cooked meat shrinks as proteins contract


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Q: Why does meat shrink so much when it’s cooked? It even seems to weigh less, so it’s not just that it’s taking up less space.

Answer: Your observation is correct if you’re looking at grilled, fried or roasted meats.

Red meat in general is about 15 to 20 percent water. Depending on how it is cooked, and how well done it is cooked, more or less of that water is cooked out and evaporated. So a piece of meat will weigh less after it’s been cooked. It will also be smaller — again depending on the method of cooking and how well done it is cooked.

When proteins are heated they tend to contract. Think of the space your hand takes up when the fingers are spread out, compared to when you make a fist. The proteins contract like that, and since they are all connected to each other, the whole piece shrinks and contracts. When they shrink and contract, the water between them is squeezed out. So an overcooked piece of meat is smaller, drier and tougher than raw meat or less-cooked meat. The moisture is gone and the proteins are now tightly contracted.

Fat in meat will help to keep it more tender, because fat among the protein strands helps keep them from contracting so much. Meat cooked by moist heat, such as braising or in a slow cooker, and meat cooked at lower temperature, will retain more of its moisture and the proteins will not contract as much. So these methods of cooking generally don’t cause as much shrinking. Still, boiling meat can tighten the proteins and shrink the meat, until it is so over-boiled that the proteins start to fall apart.

Q: How much difference is there nutritionally between modern wheat and heritage wheat? I’ve been told to look for heritage wheat at the health food stores, to help manage my gluten intolerance. I found some, but it was very expensive, and I’m wondering what else might be different.

Answer: There is no difference specifically between “heritage” and modern wheat. Genetically, modern wheat has been around for thousands of years.

There is more difference among the various types of modern wheat. Cake flour is made from wheat that has less protein (gluten). Pasta and bread flours have more protein. The difference is what allows cakes to be tender and bread slices to hold together. But even within the same variety there will be differences, depending on where the wheat was grown, the soil fertility and varying weather conditions.

Other differences in variety include whether the wheat has a tall stalk or a short one, whether it has long or short bristles on the head, and whether it’s better adapted for cold or heat and wet or dry areas. But these don’t affect the nutritional values.

Gluten intolerance is basically a genetic condition that makes a person sensitive to the natural proteins in wheat. If you are gluten intolerant then you need to avoid all wheat and anything made with wheat. Switching to heritage wheat or any other grains that make gluten will not solve the problem. Rye, barley, emmer, triticale and kamut, as well as wheat germ, wheat bran, couscous, bulgar and farina all need to be avoided. And everything that includes wheat as an ingredient, from soy sauce to beer, will need to be avoided. There are a lot of suppliers of gluten-free products on the market these days.

Mary A. Keith, a licensed dietitian and health agent at Hillsborough County Extension, can be reached at mkeith@ufl.edu.

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