The organic acids that are accumulated in the flesh of fruits: occurrence, metabolism and factors affecting their contents - a review

Organic acids are abundant constituents of ripe fruits and are responsible for their sourness. In addition, they contribute to their flavour. In many fruits, the most abundant organic acids are malic and citric. The aims of this review are two-fold. The first is to provide a clear overview of malic and citric acids in the flesh of fruits. The abundance of different organic acids in commercially grown fruits is described. How this abundance changes during fruit development is outlined. The metabolic pathways used in the synthesis and dissimilation of malic and citric acids in fruits are described. The functions of malic and citric acids in the flesh of fruits are discussed. Secondly, how environmental and cultural practices can alter the organic acid content of fruits is considered.