Lemon Juice will keep foods such as apples, pears, and avocados, even in guacamole, from losing their color between slicing and serving. This may not be necessary if you are adding salad dressing at once. We used to use lemon juice when we were freezing peaches so they wouldn’t turn dark.
Keep Lemon Juice on Hand. Freeze lemon juice in ice trays and store the cubes in freezer bags, frozen for individual portions. Each cube equals about two tablespoons of lemon juice.
Lemon or lime sections are often added to plates of fish because lemon juice enhances the flavor of fish and other foods too. Citrus makes food more appetizing in low-sodium diets. Use it on melons to bring out flavor. Squeeze lemon juice over cooked vegetables and raw fruit to preserve their appealing color.
Citrus peels are famous for flavoring. Ann Uual tells of a friend who always asked if she wanted to have lemon sponge cake or orange sponge cake. When she decided, the hostess grated the requested rind in the batter. Evelyn Hamilton remembers that her mother always peeled an orange round and round in one piece and kept the curly strip on a hook in the kitchen where it dried. “She did not have a grate but she’d cut that peel with kitchen shears into tiny pieces and used it, especially on sweet potato soufflé and other sweet potato dishes. Grated citrus rind is aptly called zest as it can be used to add flavor and zest to many recipes from meat to muffins, curries to cakes. The colored part of the rind, called the flavedo, is very rich in aromatic oils and is used to add unique flavors to recipes. Try to avoid getting any of the white inner rind, the albedo, in with the zest because it tends to have a bitter taste, though is otherwise harmless and indeed rich in vitamin C.
Choose fruit that is free of pesticides, wax, dyes and blemishes. Wash and dry it well. Grate or peel for zest before juicing or eating the fruit. One average orange will yield about 1 tablespoon of zest, one large orange 2 tablespoons. Limes vary according to the thickness of the flavedo, but Key limes are too thin-skinned for zest. The fruit with pebbly skin rather than smooth skin gives the best zest.
From Monica Moran Brandies book "Citrus"