Widen the functionality of flavonoids from yellow onion skins through extraction and microencapsulation in whey proteins hydrolysates and different polymers

In this study, whey proteins hydrolysates, pectin and maltodextrin were utilized to encapsulate flavonoids extracted from yellow onions skins by freeze drying. In a first step, the phytochemicals profile, antioxidant activity of the extract and microencapsulated flavonoids were characterized. Further, the bioinformatics tools showed that the main whey proteins are highly susceptible to proteinase K hydrolysis. Three four-residues long peptides resulted through beta-lactoglobulin hydrolysis matched longer sequences indexed in PepBank, for exerting antimicrobial and angiotensin-converting enzyme inhibitory activities. Our results indicated that maltodextrin/pectin/whey proteins hydrolysates ratio of 2:1:0.4 was more efficient in encapsulation of flavonoids, with encapsulation efficiency of 66.46 +/- 0.18%. The confocal laser scanning microscopy highlighted the presence of spherical, filamentous or polygonal particles. The supplementation of fermentation medium with 0.5% of powder had a positive effect on preservation of the viability of Lactobacillus bifermentans. The stability of flavonoids during storage showed a slightly release of flavonoids in selected variants.