Phenolic composition and antioxidant capacity of yellow and purple-red Ecuadorian cultivars of tree tomato (Solanum betaceum Cav.)

Abstract

Tree tomato fruits the yellow giant purple and New Zealand purple cultivars, cultivated in Ecuador were analysed for their phenolic composition and antioxidant capacity. Twelve hidroxycinnamoyl derivatives and fur anthocyanins (in the purple cultivars) were detected and identified. The hydroxicinnamoyl derivaties mostly derived from caffeic acid, being 3-0-caffeoylwuinic acid and rosmarinic acid the majority compounds. Furthermore, various rosmarinic acid glucosides, caffeoyl glucoside, feruloyl glucoside and two ferulic acid dehydrodimers were tentatively identified. The presence of rosmarinic acid is particularly relefvant as it constituted a majority phenolic compound in the four studied tree tomato cultivars and it had not been reported previously in this fruit. In the purple cultivars main anthocyanins were pelargonidin 3-0-rutinoside and delphinidin 3-0-rutinoside. The New Zealand purple cultivar was by far the richest sample in both hydroxycinnamates (421.6 mg/100 g dry pulp) and anthocyanins (168.9 mg/100 g dry pulp). Antioxidant capacity, as determined by FRAP, ABTS and ORAC assays, followed the same pattern as phenolic contents, with the New Zealand purple cultivar being the one with the highest and the yellow giant cultivar with the lowest values.