From Grape By-Products to Enriched Yogurt Containing Pomace Extract Loaded in Nanotechnological Nutriosomes Tailored for Promoting Gastro-Intestinal Wellness

Abstract

Grape pomace is the main by-product generated during the winemaking process; since it is still rich in bioactive molecules, especially phenolic compounds with high antioxidant power, its transformation in beneficial and health-promoting foods is an innovative challenge to extend the grape life cycle. Hence, in this work, the phytochemicals still contained in the grape pomace were recovered by an enhanced ultrasound assisted extraction. The extract was incorporated in liposomes prepared with soy lecithin and in nutriosomes obtained combining soy lecithin and Nutriose FM06^®, which were further enriched with gelatin (gelatin-liposomes and gelatin-nutriosomes) to increase the samples' stability in modulated pH values, as they were designed for yogurt fortification. The vesicles were sized ~100 nm, homogeneously dispersed (polydispersity index < 0.2) and maintained their characteristics when dispersed in fluids at different pH values (6.75, 1.20 and 7.00), simulating salivary, gastric and intestinal environments. The extract loaded vesicles were biocompatible and effectively protected Caco-2 cells against oxidative stress caused by hydrogen peroxide, to a better extent than the free extract in dispersion. The structural integrity of gelatin-nutriosomes, after dilution with milk whey was confirmed, and the addition of vesicles to the yogurt did not modify its appearance. The results pointed out the promising suitability of vesicles loading the phytocomplex obtained from the grape by-product to enrich the yogurt, offering a new and easy strategy for healthy and nutritional food development.

Keywords: antioxidant activity; dextrin fibers; enriched yogurt; gelatin; gut protection.

Figure 1

Representative cryo-TEM images of grape pomace extract loaded liposomes (A), nutriosomes (B), gelatin-liposomes (C) and gelatin-nutriosomes (D).

Figure 2

(A) Viability of Caco-2 cells incubated for 48 h with grape pomace extract in dispersion or loaded in liposomes, nutriosomes, gelatin-liposomes and gelatin-nutriosomes, diluted at different concentrations (40, 4 and 0.4 µg/mL). Mean values ± standard deviations were reported (n = 8). Same letter (a) indicates not statistically different values (p > 0.05 versus untreated cells) and statistically different from other (p < 0.05 versus other formulations). (B) Viability of Caco-2 cells stressed with hydrogen peroxide (1:40,000) and treated with grape pomace extract (4 µg/mL) in dispersions or loaded in liposomes, nutriosomes, gelatin-liposomes and gelatin-nutriosomes. Mean values ± standard deviations were reported (n = 8). Same letter (a and b) indicates not statistically different values (p > 0.05 versus untreated cells) and statistically different from other (p < 0.05 versus other formulations).

Figure 3

Viscosity values of yogurt containing different concentrations (0, 5, 10 and 20%) of liposomes, nutriosomes, gelatin-liposomes and gelatin-nutriosomes. Mean values ± standard deviations (error bars) were reported. Same letter (a, b, c, d, e, f, g and h) indicates not statistically different values (p > 0.05), while different letters indicates statistically different values (p < 0.05).