Ultrasound-assisted extraction of anthocyanins from grape pomace using acidified water: Assessing total monomeric anthocyanin and specific anthocyanin contents.

This study aimed to optimize the ultrasound-assisted extraction (UAE) of anthocyanins from oven-dried and freeze-dried Vitis labrusca grape pomace, using acidified water as the solvent. The effects of power density (8.3-16.7 W/mL), pulse interval (0-2 s), and extraction time (1-5 min) on both total and specific anthocyanins were investigated. The findings suggested that acidified water can be a viable alternative to conventional solvents and that oven drying was an effective method for drying the pomace. Using response surface methodology, the study identified power density and extraction time as key factors influencing total anthocyanin content, with extracts reaching contents up to 2.56 mg/g. The analysis using LC-MS identified 14 anthocyanins, while NMR quantified 3 and malvidin diglucoside was generally the most abundant. However, higher power and longer extraction times were found to reduce its content while increasing malvidin monoglucoside content, suggesting ultrasound-induced anthocyanin hydrolysis. In conclusion, this study presents a sustainable method for extracting anthocyanins using acidified water, contributing to the valorization of Vitis labrusca grape pomace for industrial use.

Impact of orange juice containing potentially prebiotic ingredients on human gut microbiota composition and its metabolites.

Orange juice containing oligosaccharides and dextran was assessed, after in vitro digestion, in a fermentative system with fecal microbiota from two donors (A and B) in anaerobiosis (37 °C/48 h). Microbiota analysis was performed using 16S rRNA sequencing, and HPLC quantified the metabolites. Oligosaccharides and dextran were resistant to digestion and were consumed during colonic fermentation. Lactate and acetate were the main metabolites, followed by butyrate, propionate, and isobutyrate. High propionate accumulation and fast consumption of oligosaccharides were observed for donor B. Lactobacillus ruminis (44.96 %) presented an increased relative abundance for donor A. Bifidobacterium adolescentis (41.73 %) was remarkable for donor B after fermentation. In addition, the functional orange juice promoted the growth of emerging probiotics such as Bacteroides xylanisolvens and reduced some strains, such as Clostridia sp. Thus, the potentially prebiotic orange juice enhances gut microbiota composition and might be a suitable product for the functional food market.