Aside from their myriad of other uses, lemons can also temporarily prevent many recently cut fruits from turning brown. Even when it's fresh, discolored fruit can be extremely unappetizing, so this trick can be useful when preparing anything from fruit salad to guacamole. All you need to do is squeeze lemon juice over the sliced produce, and it should keep its original coloring -- at least for a little while. The effect will last anywhere from a few minutes to several hours and works with many fruits, including avocados, apples, nectarines, pears, peaches and apricots.
However, while the acidity of lemon juice may forestall the fruits' natural oxidation process, it will also affect the flavor of the foods in question [source: Florida Agricultural]. Most people find that the lemon juice enhances the taste of most of the foods it helps protect, but your taste buds will be the judge of that.