The nutrition column in the Food Section Wednesday stated incorrectly that "chocolate comes from carob beans." Chocolate is a product of cacao beans.

Q. Can you tell me what chocolate liquor is? I sometimes see it listed among the ingredients of chocolate products.

A. Chocolate liquor really is the same thing as the bitter chocolate blocks you use in baking. Chocolate comes from carob beans, which grow in elongated melon-shaped seed pods, with each pod holding as many as 40 beans. The beans may be white or pale purple in color, and must undergo a number of processing steps before they yield the liquor.

Fermentation, the first step, alters the flavor and turns the color to cinnamon brown. Next the beans are dried to a low moisture level. This improves the keeping quality and allows the skins to be removed easily. It is at this point that the product is exported.

Once in the manufacturing plant, the beans are roasted to further develop color and flavor. The seed coat and the germ are then removed, and the hulled and degermed beans, now called "nibs," are put through several milling processes and ground. The heat of the grinding melts the fat, and the ground nibs become liquid. These melted nibs, containing about 55 percent fat, are what is known as chocolate liquor.

Q. What causes the color changes in beef as it cooks?

A. These changes are related to the effects of heat on the iron-containing pigment called myoglobin. In raw meat, especially in the interior of a cut, much of this myoglobin is in the unoxygenated state. With some heat, the pigment takes on oxygen and is converted to the cherry-red oxymyoglobin. Further heating alters the structure of the protein part of the pigment. The iron is oxidized and the meat takes on a grayish-brown color. The pigment is now called denatured globin hemichrome.

It is the extent of this alteration in the protein structure of myoglobin that explains the variation in color from a rare roast, which has only a thin brown exterior layer, to the uniformly brown color of a well-done piece of meat.

Q. I was interested in your recent explanation of how imitation crab legs are made from the fish paste called surimi. Soon after reading that, I saw a short article that said that surimi was being used to produce hot dogs. Can you tell me more?

A. Fish sausages are not new. They are one of the numerous products the Japanese make out of surimi. Kamaboko, as it is called, is a white, bland surimi food prized for its rubbery texture, created simply by chopping the fish paste with enough salt to extract certain proteins, then shaping the mixture into the desired form, and heating it to make a gel.

Even in this country, food technologists for almost 20 years have periodically reported attempts to replace red meat with fish muscle in frankfurter-type products. However, these foods all contained relatively large amounts of fat and were frequently found to have an undesirable soft texture.

A recent effort may offer more promise. Researchers from the Department of Food Science and Nutrition at the University of Massachusetts at Amherst produced a fish sausage made from an underutilized species called red hake. It has been shown to yield an acceptable protein gel (which would replace the role of fat emulsion in providing texture to the hot dog) and less than 0.5 percent fat.

The fish mixture was seasoned with white pepper, garlic, paprika, coriander and liquid smoke, and colored with liquid beet juice. Sodium nitrate and sodium erythorbate were also added before it was shaped and processed.

The resulting product is essentially fat-free and therefore quite low in calories (90 calories per 3.5 ounces versus 195 and 343 in the same amounts of chicken and beef-pork frankfurters, respectively). Though hardly low in sodium, it also contained less than the other supermarket products with which it was compared (670 milligrams per 100 grams compared to anywhere from 835 to 1153 milligrams in the standard beef, beef-pork, turkey and chicken products).

But do people like them? Taste evaluations were not an unequivocal success. The fish hot dogs failed to achieve levels of acceptance comparable to those for beef or beef-pork franks. But they did compete well against chicken franks, especially if fresh rather than frozen surimi was used to produce them. It is an open question whether these low-fat alternatives will ever become a ball game favorite.