Composition, accumulation dynamics and extraction of carotenoids in citrus fruits: a review

Citrus, the genus Citrus L., can be considered one of the most important fruit crops. It is known to be rich in bioactive compounds such as carotenoids, flavonoids, vitamins, phenolic acids, pectins, and fatty acids with nutritional and nutraceutical value. Particularly, carotenoids contribute to the characteristic coloration of mature fruits and possess beneficial health-related effects. The concentration and composition of carotenoids can vary, and it is based on the maturation stage, fruit part, cultivation region, handling and cultivar. In light of this, this review provides a comprehensive view of chemistry, the composition of carotenoids and their accumulation in various citrus fruits. Besides, the possibility of recovering carotenoids from citrus by-products is investigated by analyzing several extraction methodologies, including traditional processes and the most recent ones. This review summarizes systematically the existing bibliography on the accumulation and composition of carotenoids in different citrus cultivars by highlighting the carotenoid profiles and metabolic changes. A deep understanding of this information may supply scientific guidance for better-utilizing citrus and citrus by-products to benefit the extension of the citrus value chain.