Effect of Ultrasound on In Vitro Bioaccessibility of Phenolic Compounds and Antioxidant Capacity of Blackberry (Rubus fruticosus) Residues cv. Tupy

Agro-industries residues of fruit are a source of antioxidant compounds with a possible health impact. The aim of this study was to evaluate the total phenolic content (TPC), total monomeric anthocyanins (TMA), individual phenolic compounds (IPC), antioxidant capacity and in vitro intestinal bioaccessibility from blackberry residues (BR), and ultrasonicated blackberry residues (US-BR). The results showed that BR had higher TPC (4,016.43 mg GAE/100 g DM), TMA (364.53 mg Cy-3-Gl/100 g) antioxidant capacity by ABTS (5,422.38 mg AAE/100 g DM) and FRAP (12511.44 μmol Fe(II)/100 g DM) than US-BR. TPC and TMA obtained by US-BR were more bioaccessible (70 and 51%, respectively) compared to BR (37 and 34%, respectively). The use of ultrasound can aid the extraction of total phenolic compounds and improve their bioaccessibility. After acid hydrolysis, a high amount of individual phenolic compounds (IPC) in US-BR (chlorogenic acid, caffeic acid, apigenin, luteolin and kaempferol) was obtained compared with BR. Before in vitro digestion, total individual compounds (TIC) content was lower in the BR (29.49 mg/100 g DM) than US-BR (92.36 mg/100 g DM) and there was 5 and < 1%, respectively. Therefore, the food industry would use residues of blackberry fruits as a source of antioxidant compounds with possible health benefits.

Consecutive high-pressure and enzyme assisted fractionation of blackberry (Rubus fruticosus L.) pomace into functional ingredients: Process optimization and product characterization

In this study supercritical carbon dioxide (SFE-CO₂) and pressurized liquid (PLE) extractions were optimized for the recovery of valuable fractions from blackberry pomace. Consecutively applied SFE-CO₂ and PLE at optimized parameters yielded 9.9, 26.3 and 5.1 g/100 g of CO₂, ethanol (EtOH) and water-soluble extracts, respectively. Oil of lipophilic fraction was composed mainly of healthy polyunsaturated fatty acids (linoleic 64.1%, α-linolenic 12.9%), while polar solvents effectively recovered antioxidants (up to 29.1 mg gallic acid and 168.7 mg Trolox equivalents from g pomace). PLE-EtOH extract contained 12.2 mg/g of cyanidin-3-glucoside, while other anthocyanins were detected in significantly lower quantities (0.5-0.7 mg/g). SFE-CO₂ and PLE reduced the antioxidant capacity of starting plant material by 86-93%. In terms of extraction time, solvent consumption, total yields, and phytochemical characteristics, high-pressure fractionation was more efficient for obtaining valuable pomace constituents as compared to conventional and enzyme-assisted extractions.