I have two questions. First, when corn syrup is listed as an ingredient on packages of frankfurters or bologna, how much corn syrup do they contain? Second, I remember that you once printed a toll-free number for consumers with questions about safe handling of meat and poultry products. Could you provide it again?

To answer your first question, frankfurters, bologna and similar types of cooked sausage are allowed to contain no more than 2 percent corn syrup by weight. That translates into about 1/2 teaspoon in 3 1/2 ounces of meat.

Now for your second question: The USDA's Meat and Poultry Hotline number is 1-800-535-4555. It operates from 10 a.m. to 4 p.m., Eastern time. Washington, D.C., residents can call 447-3333. (These numbers, incidentally, are accessible by Telecommunications Devices for the Deaf.)

One final note: A free booklet is available to help consumers better understand labeling of meat and poultry products. To send for your copy of "Meat and Poultry Labels Wrap It Up," write F. James, Consumer Information Center, Pueblo, Colo. 81009. The pamphlet was prepared by the Food Safety and Inspection Service, which runs the Meat and Poultry Hotline.

I am expecting my first child soon. I know that there are advantages to breast-feeding, but I don't think it will be possible for me. I have been reading about infant formula, and note that some brands advertise that they have different types of protein mixtures. Is one kind better than another?

Reaching a decision about what formula to use is best done with your pediatrician. Plan to discuss this and any other questions you may have before the baby is born.

However, we can tell you about the results of a recent study of formulas that found no difference in child growth. One group of infants was fed a predominantly whey-protein formula. Another was given a formula in which the main protein was casein. Both groups were compared to breast-fed infants. Babies in all three groups received essentially all of their calories from formula or breast milk for 16 weeks after birth. Parents of formula-fed infants did not know which type of formula they were using.

All parents were of similar ethnic and socio-economic backgrounds, and all mothers had received the same prenatal care at a single clinic.

As it turned out, there were no significant differences in weight, length, body fat or lean-body mass at several intervals from the time of birth until the infants were 16 weeks of age.

What is couscous and how many calories does it contain?

Couscous refers either to semolina flour, which is moistened and rolled into tiny balls, or to the stew-like mixture which is the national dish of Morocco. In the latter form, it usually contains meat or chicken, vegetables and often some dried fruit and spices.

It is not a food commonly eaten in this country, so exact nutrient values are not available. However, because it contains only flour, it is reasonable to assume that it is calorically similar to a pastina, of which 2 ounces dry ( 1/3 cup) would provide 200 calories.

The complete dish, including the grain and stew-like mixture, is prepared in a special pot akin to a double boiler, with holes in the bottom of the upper pan. That allows steam to rise and cook the couscous grain. If you are interested in making your own, you will find an enthusiastic description not only of couscous but of other Moroccan dishes in a book by Paula Wolfert, now available in paperback for $10.95, entitled "Couscous and Other Good Food from Morocco" (New York: Harper and Row, 1973).

Wolfert provides no less than 17 versions of Moroccan couscous and descriptions of many others. She warns that package directions for preparing the couscous grain may be simplified, but the results are less than satisfactory. The couscous will lump.

How long can I store ground beef in the refrigerator?

Step one is to handle it correctly. Bring it home from the store promptly and then store it in the coldest part of the refrigerator. If this is done, it may be kept for a couple of days. After that, it's safest in the freezer.

Ground beef perishes more easily than solid cuts. It is often made from trimmings, which have been handled more than other cuts, contributing to the bacterial count. In addition, grinding greatly increases the surface area exposed to bacteria naturally present in the environment. These microscopic organisms are not harmful, but can cause both deterioration in quality and spoilage when meat is not handled properly.

Frozen ground meat is best thawed in the refrigerator. When that is not possible, the thawing process can be accelerated by placing the meat in a watertight bag in cold water. Be sure to use the meat as soon as it is thawed.

I have a good friend who takes yeast as a protein supplement. Is that a good idea?

We would be hard put to recommend it. An ounce of yeast does provide about 11 grams of protein, roughly equivalent to the amount in 1 1/2 ounces of meat. However, that is about 1/4 cup, rather a formidable amount to consume unless you happen to like the taste.

Besides, the protein in yeast, a plant food, is not complete. That means it does not contain all the essential amino acids necessary for growth and repair of body tissue. In this case, the sulfur-containing amino acids are lacking. In order for the body to use it efficiently, it should be taken with a variety of other protein foods. Finally, yeast tends to be a relatively expensive source of protein.

But beyond all that arises a far more basic question: Is it wise to take any protein supplement at all? In this country most of us get much more protein than we need to meet the body's requirements for growth and repair. Any extra is either burned for energy or stored as fat. So why take it in the first place?