I make a saute'ed, lemon-flavored broccoli dish which is delicious, but the broccoli is gray in some spots, bright green in others. What's wrong with the recipe?

You can't add an acidic ingredient to broccoli while it is cooking and expect a uniformly bright green color. Lemon juice contains citric acid, the acidic "elements" of which, called hydrogen ions, alter the green pigment chlorophyll in broccoli to a grey-green derivative. This happens especially quickly if the vegetable is cooked in the presence of acid. As the broccoli's cells are subjected to heat, the hydrogen ions quickly permeate the external layers and produce the off-color.

It is possible to add lemon juice to broccoli and still obtain a bright green -- at least for an hour or two. If you blanch or parboil the broccoli first and add the acid to the cool vegetable, the broccoli will retain its bright green for a while. Here is your revised recipe, which should look prettier in the future. BROCCOLI ANTIPASTO (6 servings)

2 quarts water

2 1/2 teaspoons salt

2 pounds broccoli

1 lemon

1/4 teaspoon red pepper flakes

2 tablespoons extra-virgin olive oil

Bring water and salt to a boil in a 2-quart saucepan. Cut broccoli flowers off stems (save stems for another recipe such as a stir-fry) and plunge into rapidly boiling water. Cook 5 minutes or until stems of flowers are barely cooked. Drain through a colander and spread on a plate or platter to cool.

With a swivel-bladed potato peeler, remove zest (yellow only) of lemon. Cut into very thin, delicate strips and then cut these about 1/2 inch in length (or, if you have one, use a zester to make finer and prettier lemon strips). Saute' lemon strips and red pepper flakes in olive oil for several minutes (do not brown). Add broccoli and toss together to distribute flavors. Just prior to serving, squeeze half the lemon over the broccoli.

When is it important to bring ingredients to room temperature before cooking or baking them? When must ingredients be kept cold?

There are two situations where recipes mention the temperature of raw materials before beating, stirring or blending them to produce a finished product. One is in the making of a meringue. The recipe usually says to use room temperature eggs, from which the whites are separated, then beaten into a foam. Although research has shown that one can obtain as much as 30 percent greater volume from room temperature egg whites, I have produced quite satisfactory meringues from cold egg whites. So, I never follow this instruction.

The second situation where recipes mention the temperature of raw materials is in the production of cakes. Here, temperature has a critical effect on the volume and texture of the finished product. If you start out with cold butter and eggs, you will not be able to cream the butter sufficiently with the sugar to obtain a fine-textured foam. This, in turn, leads to cakes with coarse texture. Cold eggs can cause separation and curdling of the batter, and this may lead to loss of volume and to a tougher, denser cake.

Ingredients that are highly perishable should be kept cold until the last minutes. Fish and meats, which are excellent media for the growth of spoilage bacteria and which contain tissue-degrading enzymes, should be kept cold up until the moment they are cooked.

The handling properties of heavy cream depend on its coldness. If not kept cold before whipping, it curdles and produces butter instead of a thick, fluffy topping. Butter is also sensitive to temperature. If you leave butter-based pastry and cookie doughs at room temperature for any length of time, the doughs turn oily, and when baked, either produce a crumbly pastry or cookie, or cause a thin or crisp product. This may not be what you want.mat