Gelatin as Good Protein Source

Times Staff Writer

Question: One of my diet books recommends including gelatin salads in menus, as these are not only low in calories but provide a good amount of protein and bulk as well. Is gelatin really a good source of protein? Where does gelatin come from?

Answer: Gelatin is classified as an incomplete protein, that is, it is incapable of replacing or building new tissue and hence cannot support life. (Another good example of incomplete protein is the protein in corn.) The reason is that gelatin lacks or is low in some of the essential amino acids. Essential amino acids are those that cannot be synthesized in sufficient amounts by the body and therefore must be provided in the diet. Gelatin contains almost none of the essential amino acid tryptophan and has very small amounts of the essential amino acids threonine, methionine and isoleucine.

However, gelatin can become a good source of protein if it is consumed at the same meal with any of these protein-rich foods: meat, cheese, milk, eggs or fish.

The protein in gelatin, collagen, is found in the bones, tendons, muscle, skin, cartilage, hide, horns and hoofs of most animals. Most gelatin in this country is made from pig skin, which is treated in a lime solution. The gelatin is then extracted by boiling in acidic water, and later filtered and evaporated. Dried in sheet form, the gelatin is finally granulated.

Q: I have forgotten the difference between bleached and unbleached flour. Can you please refresh my memory? So many recipes now call for unbleached flour.

A: After flour is milled, it has a yellowish color and needs aging for the color to whiten. Aging also strengthens the flour's gluten content. All-purpose bleached flour is flour that is treated with bleaching and maturing chemical agents to hasten the aging process so the flour will be white.

Unbleached all-purpose flour is milled flour that is stored and aged for several months to improve the color; the final product, however, still is a pale wheat color. There is no discernible difference in flavor between the two types of flour but some bakers say that unbleached flour produces a more resilient dough with high volume.

Q: Should flour be sifted at all times?

A: No. Unless the recipe says to do so, flour should not be sifted. When measuring flour, scoop it with the measuring cup until it mounds slightly over the top, and then level off with a spatula. Do not shake or tap the cup before leveling off the top. Sifting flour before measuring will produce a slightly smaller yield than is called for in some recipes.

Q: I notice that when I wash my aluminum pots and utensils in the dishwasher, they become dull in color. Why is this?

A: When aluminum utensils are washed in a dishwasher, they are subjected to hot water for a long period. Chemical changes take place between the salts in the water and the detergent, which is alkaline, causing dullness and in some cases, actual darkening. Boiling water in an aluminum pot will cause the same reaction. For brighter aluminum pots and utensils, wash them by hand.

Address questions on food preparation to You Asked About . . . , Food Section, The Times, Times Mirror Square, Los Angeles 90053. Personal replies cannot be given.

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