The perception
Flavor like appearance and texture, is a function of chemical composition. Sweet, sour, bitter and astringent are the taste attributes of plant products. Sweetness is a property of organic acids. Glucose, fructose and sucrose predominate on fruits, with a wide variation. Citric acid is the primary acid presenting citrus fruits, while malic and tartaric acids predominate in apples and grapes, respectively. The perception of sweetness or sourness however, is primarily related to the ratio of sugar to acid present, particularly in sweet fruits and their products.Sugar and acid ratio
Ripening of fruits usually involved the increase of sugars and the decrease of acids. In other crops such as sweet corn, sugars are converted into starch, which is undesirable. Sweetness is not desirable in all fruits and vegetables, however. The total sugar and acid content contributes to the flavor of tomatoes, and the presence of sugars in potatoes leads to objectionable browning in fried products such as chips and French fries. Other chemical compounds in citrus fruits are bitter, while tannins impart astringency.
Flavor Chemistry
Flavor is a combination of taste and aroma. Flavor impart compounds such as nootkatone in grapefruit and benzaldehyde in cherries are complemented by numerous other chemicals to give the distinctive aroma that we associate with a particular fruit and is so di
fficult to reproduce synthetically. Vegetables tend to have more delicate aromas, some of which are attributed to specific compounds, such as phthalides in celery. And others are metabolites of lipoxygenase. A conversion of compound present in the fresh flavor, e.g., the formation of alkyloxazoles to give the characteristic aroma of French fries potatoes.Perception of Quality: Flavor
