Changes in phenolic composition, ascorbic acid and antioxidant capacity in cashew apple (Anacardium occidentaleL.) during ripening

Abstract

Introduction. Cashew apple is a rich source of sugars, vitamin C and polyphenols. In spite of its nutritional value, this pseudo-fruit has been left unexploited to a large extent in the crop-growing areas. Some reports of the chemical characteristics of cashew apple have been published. However, nothing is known about the changes in the composition of its bioactive compounds in the course of ripening. Materials and methods. Cashew apples at three different maturity stages were examined with respect to their ascorbic acid content, phenolic compounds and antioxidant capacity. Ascorbic acid was quantified by HPLC. Phenolic compounds were identified and quantified by using HPLC-ESI-MS/MS by comparison with authentic standard compounds. The antioxidant capacity was measured by TOSC assay against peroxyl radicals and peroxynitrite. Results. Amounts of identified phenolic compounds were the highest in unripe cashew apple and decreased in the course of ripening. Myricetin 3-O-rhamnoside, quercetin 3-O-galactoside and quercetin 3-O-rhamnoside turned out to be the main flavonoids in all maturity stages. The antioxidant capacity and the concentration of ascorbic acid increased in the course of ripening. The antioxidant activity was considerably influenced by ascorbic acid, more than by the content of phenolic compounds. Conclusion. This study provides, for the first time, information on changes in bioactive compounds and the antioxidant capacity in cashew apple during ripening. A dietary or technological exploitation of ascorbic acid is useful in the ripe condition. The unripe pseudo-fruits are a good source for the extraction of polyphenols with regard to possible food technological purposes or the preparation of food supplements.