Recovery of eggplant field waste as a source of phytochemicals

The influence of ripening stage was evaluated on fruit characteristics of three widely cultivated eggplant cultivars (Birgah, Black Bell and Black Moon), with the aim to characterize their fruit residual waste for phytochemicals extraction. At overripening stage, eggplant fruits showed the highest average weight, dry matter content and weight incidence of the pulp. Total anthocyanins concentration of the peel (mainly represented by nasunin) was higher at commercial ripening, whereas total polyphenols (most of all 5-O-caffeoylquinic acid) and steroidal glycoalkaloids (α-solasonine and α-solamargine) peaked at the overripening stage. Because of these modifications, every ton of fresh fruit gave up to 59 g of total anthocyanins, 1054 g CAE of total polyphenols and 252 g of total glycoalkaloids, depending on cultivar and fruit ripening stage. This study highlighted the possibility to manage the choice of cultivar and harvest time in the view of valorise this raw material for phytochemical extraction.