9. Fruits

In a botanical sense, fruits are the developed part of the seed-containing ovary. Evolutionarily speaking, plants have developed fruits presumably to attract insects, birds, reptiles, and mammals and hence to spread the seeds. Fruits can be dry such as the pod of a pea, or fleshy such as a peach. As humans, we enjoy fleshy fruits for their flavor and nutritional value. In this chapter, we will review the common volatiles that are produced by the major fruits with commercial value: tomato, citrus, apples, and strawberries. Some volatile compounds are commonly produced by all crops, simply by the fact of common biosynthetic pathways, while other compounds are specific to certain fruit species. Fruit-specific aroma depends on species, cultivar, growing conditions, and developmental and maturity stage. In the end, however, what gives a fruit its specific flavor is the combination of volatile and nonvolatile compounds, including sugars, acids, and other water-soluble and insoluble compounds.