Development and charaterization of functional ingredients through the valorization of non-compliant Portuguese fruit: Bravo de Esmolfe apple and Saco cherry

Nowadays, a special interest has increased on the recovery of phenolic compounds from non-compliant fruit, since they do not have market value and cannot be sold, thus an effort to find value-added solutions for these products are of most importance. Traditional Portuguese fruit varieties, such as Saco (SC) cherry and Bravo de Esmolfe (BE) apple, are nutritionally important fruit rich in powerful bioactive compounds, such as phenolic compounds, fiber and pigments. In this context, the main goal of the present work was to develop functional ingredients through the valorization of non-compliant traditional Portuguese fruit: Saco cherries and Bravo de Esmolfe apples using green safe methodologies such as ultrasound and microwave assisted extraction and food-grade solvents. In order to achieve the proposed goal, four different extraction methodologies were applied (two conventional vs two green methodologies) the functional extracts were analyzed in terms of phenolic compounds and antioxidant activity. Applying microwave assisted extraction (MAE), SC cherry extract showed a total phenolic content of 12.65 ± 0.81 mg GAE/g DE and a total anthocyanin content of 2.53 ± 0.13 mg Cy-3-glu/g DE. The extract revealed 40 different phenolic compounds, with high amount of chlorogenic acids (mainly 3-caffeoylquinic acid and 5-caffeoylquinic acid), cyanidin-3-rutinoside and p-coumaroylquinic acid, comparatively with other extraction methodologies. Regarding the antioxidant activity, as expected, due to the high number of phenolic compounds, MAE extract showed higher activity (confirmed through ABTS˚, DPPH˚ and ORAC). In BE apple extract the total phenolic content was 4.44 ± 0.32 mg GAE/g DE with 30 phenolic compounds identified, encompassing a high amount of 5-caffeoylquinic acid, (-)-epicatechin, (+)-catechin and procyanidins, phloridzin, phloretin and quercetin glucosides. To the best of our knowledge, no data was reported about the effect of microwave and ultrasound assisted extraction on the recovery of phenolic compounds from BE apple and SC cherry demonstrating the potential and innovation of this study. In sum, the work performed in this Master thesis opens the door to the future application of microwave technology in industry for the extraction of bioactive compounds from traditional Portuguese non-compliant fruit, which until now have been used in low value applications, such as animal feed.