Dictionary - O

Olive Oil
Pressed from the fruit of the olive tree, grown in Italy, France, Greece, Spain and California, olive oil is a staple for both cooking and dressing salads. The different varieties of olive oils are graded on their degree of acidity and pressing process. Extra virgin, considered the finest olive oil, results from the first, cold pressing, and it contains 1 percent or less oleic acid. Virgin also comes from the first pressing, but contains between 1 and 3 percent oleic acid. Pure olive oil (3 percent acid) is extracted from the second pressing and is heat or chemicaly processed. Light olive oil doesn’t refer to caloric content, but its color and fragrance and nondescript flavor. Extra virgin and virgin oils are not suited to frying at high temperatures; for sautéing, choose a mild olive oil labeled "extra light" or "light." Store in a cool, dark place for up to 6 months. Exposure to air, light and heat causes its flavor to fade more quickly. Olive oil can be refrigerated, but there is no reason to do so. When Chilled, it may solidify, but it will become clear and liquid again once at room temperature.

Oxidation
A chemical reaction that occurs when a substance is exposed to oxygen. The oxygen reacts with elements in the substance to change it. The color of food is often affected, as when cut apples turn brown.