Some plants contain fragrant substances that can be separated and used to flavor food. These are known as vegetable flavoring extracts. Those commonly so used are the essence of vanilla, almond, orange, lemon. Lemon and orange extracts when pure are made from the oil of the fruit-peels. This is dissolved in alcohol. In the United States it is required that in these extracts one twentieth be the fruit-oil itself. Almond extract is oil of bitter almonds dissolved in alcohol.

Vanilla is extracted from the vanilla-bean, the fruit of a tropical climbing orchid that grows naturally in Central America and West Indies and is elsewhere produced, as in Java and very favorably in Mexico. The process of preparing vanilla consists in drying the pods, during which fermentation develops the flavor. The extract is made by soaking chopped dried pods in alcohol and sugar. Vanillin (a crystalline substance) combined with some resin, gum, wax, tannin, sugar, gives the flavor characteristic of vanilla.

Tonka extract is used as a substitute for vanilla. Sometimes it is mixed with vanilla. It is from the seed of a tropical tree. The flavoring matter (coumarin) is less delicate than that of vanilla. Like all substitute food-substances it should be sold as itself. The Pure Food Law requires this. Both vanilla and tonka extracts are artificially produced.

Twenty samples of commercial vanilla when examined showed that all except two contained less than the capacity of the bottle. All except one contained less alcohol than the amount (38%) in pure vanilla extract. Six only contained the amount of vanillin (1-2%) most desirable, which is that present in the bean considered best (Mexican). Other beans contain more. Seven contained tonka extract.

The volatile nature of flavorings makes them pervade foods.