Conjugates-based design for microencapsulation of CO2 supercritical extract from red grape by-products to provide functional ingredients

Abstract

In this study, red grape pomace from Cabernet variety was extracted by supercritical carbon dioxide using two sets of extraction conditions to recover the lipophilic and polyphenolic fractions. The extracts showed a different phytochemical profile, with a higher polyphenolic and carotenoids content in the extract obtained at a pressure of 45 MPa and temperature of 45 °C, whereas the extract obtained at 30 °C and 15 MPa showed a higher content in fatty acids, tocopherols, and phytosterols. The polyphenolic enriched extract showed good antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and Pseudomonas fluorescens. The extracts were encapsulated in two conjugated designs, based on bovine β-lactoglobulin and lactose, with and without Maillard-induced glycosylation. The powders profile evidenced a higher emulsifying capacity of the conjugated powder, which allowed greater retention of fatty acids (264.13 ± 5.11 mg/g dry weight (DW)), whereas sample without heating showed a higher content of tocopherols (1.66 ± 0.39 μg/g DW) and phytosterols (77.01 ± 3.15 μg/g DW). Both powders showed a good retention index of polyphenols and flavonoids, with an enhanced protective effect registered for Maillard-induced powder. The results are valuable for providing a comprehensive phytochemical profile of the autochthon grape variety alongside improved solutions for bioactive stabilization techniques for different applications.