Regulation of phytochemicals in fruits and berries by environmental variation-Sugars and organic acids.

Sugars and organic acids are important phytochemicals contributing to the nutrition and sensory properties of fruits and berries. Their contents are closely correlated to the genetic background of plants as well as to the environmental conditions during growth. This review focuses on the recent researches on the metabolism of these compounds in fruits and berries in response to the variation of environmental conditions, including temperature, radiation, and water supply. A great deal of investigations indicates that the influence of environmental factors on the composition of fruits/berries depended largely on the genetic background. Moreover, the metabolic regulation in response to environmental changes also varies between different plant developmental stages. Nevertheless, some general trends, like the positive correlation between light intensity and sugar content, were observed in most investigations. In grapes (Vitis vinifera L.), the content of malic acid always decreases as light intensity increases, and as the water supply decreases. PRACTICAL APPLICATIONS: The contents of sugars and organic acids, and especially their relative ratio, are important indicators determining the taste and quality of fruits and fruit products. In this review, we summarized the investigations carried out on the regulation of these sensory contributing primary metabolites in fruits and berries in relation to the variation of environmental conditions. It was indicated that various factors, such as plant genotype, growing period, and interaction between environmental factors, might contribute to the impact of environmental changes on the composition of fruits/berries. The article not only provides comprehensive knowledges in food chemistry and plant physiology but also provide important background knowledge for berry cultivation and breeding, as well as useful guidelines for utilization of fruits and berries in food industry.