EVEN THE best of cooks often have questions. Now there is someone to turn to. Tom Neuhaus, a professional cook, baker and food chemist, is here to answer reader's cooking questions.

Q. Occasionally my hard boiled eggs are impossible to peel. Why?

A. Boiling eggs causes their whites to coagulate. During coagulation, the whites' proteins unfold. The unfolded proteins are insoluble in water and form a gel.

Coagulation and firmness of the resulting gel depends on how much heat is added, how fast, and the egg's age. So if you suspect your eggs are somewhat old, or even if they aren't, add a teaspoon of vinegar and a tablespoon of salt (or more -- so as to be noticeable).

Q. Do jams and jellies spoil? Should I refrigerate them?

A. In temperate climates, refrigeration is never necessary for an unopened jam or jelly. The partial vacuum between it and the lid prevents the germination of mold spores.

An opened jar, however, is likely to mold if stored more than two months at 80 degrees. Only the top of the jam will mold. Just scrape it off with a spoon; the product underneath will be perfectly edible and its flavor will not have changed.

There is one drawback to refrigerating jams and jellies. While the cold temperature inhibits mold, it also causes the sugar to crystallize into small white lumps which many people take for colonies of bacteria. These lumps can be easily dissolved by bringing the jam or jelly to a boil and cooling.

Q. I like orange and lemon teas, but the commercial renditions are so bland. How can I make my own?

A. You can make your own by brewing an ordinary cup of tea such as Orange Pekoe and adding a piece of orange or lemon peel removed with a potato peeler. The commercial teas are made just that way, except that the peel has been finely chopped and dried. It has also lost much of its citrus oil content, and for that reason does not add the spiky freshness of peel just removed.

Use a potato peeler, not an apple corer. The peeler is much sharper and leaves the white part on the fruit. The white part is very bitter and will taint the tea.