Phenolic compounds citrus fruits

Since phenolic compounds occur in many fruits and most of them contribute to color and taste, phenolic analysis of fruits has been an active research area, especially in apple, grape, and citrus fruits and their products, such as juice, cider, and wine. 

Phenols and derivatives are the main aromatic compounds of plants, whose structural formulas contain at least one benzene ring. They serve as odors, fungicidals, or germination inhibitors. Coumarins are especially common in grasses, orchids, citrus fruits, and legumes. Plants containing phenols with anticancer properties include the following ... 

Abad-Garcia, B., Berrueta, L. A., Garmon-Lobato, S., Urkaregi, A., Gallo, B., and Vicente, F. 2012. Chemometric characterization of fruit juices from Spanish cultivars according to their phenolic compound contents I. Citrus fruits. J. Agric. Food Chem. 60 3635-3644. 

Although tomato was the matrix most studied with this technique, other matrices such as pepper, eggplant, apple, pear, beans, mango, orange, citrus fruit, onion, garlic, potato, chillies, and strawberries were also studied by UAE. The extracted phenolic compounds included phenolic acids, isoflavones, flavonols, flavonones, fla-vones, flavonones, cinnamic acids, dihydrochalcones, chalcones, flavanols, and pro-cyanidins (Table 16.3). 

Naim M, Zehavi U, Nagy S, Rouseff" RL. Hydroxycinnamic acids as off-flavor precursors in Citrus fruits and their products. In Ho CT, Lee CY, Huang MT, eds. Series 506 Phenolic Compounds in Food and Their Effects on Health I. Analysis, Occurrence, and Chenustry. Washington, DC ACS, 1992 180 191. 

The taste of fruits is influenced by phenolic compounds. The presence of tannins yields an astringent, harsh taste, similar to an unripe apple (or an apple variety suitable only for processing). Table quality apples are low in phenolic compounds. Flavanones (naringin, neohesperidin) are the bitter compounds of citrus fruits. 

Bitterness is a major problem to the citrus industry. It is of economic importance because bitter juices have a lower market value. Bitterness is mainly caused by the accumulation of two different chemical compounds limonin from the limonoid terpine group and naringin from the flavonoid phenolic group in the fruit tissues. The highest concentrations of the bitter compounds are generally found in immature fruits. As the fruits mature, the concentrations of the bitter compounds decrease. 

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