Monosaccharides, dietary fiber, bioactive compounds, functional properties and volatile compounds in both clear and cloudy kiwi juices with oligosaccharides addition fermented by Lactobacillus helveticus.

This study investigated the effects of Lactobacillus helveticus fermentation on the phytochemicals, functional properties and volatile compounds in both clear and cloudy kiwi juices with oligosaccharides supplementation (fructooligosaccharides, galactooligosaccharides and isomaltooligosaccharides). Results demonstrated that oligosaccharides supplementation reduced glucose and fructose consumption while enhancing the utilization of dietary fiber. In fermented cloudy kiwi juice, the highest total flavonoids (694.78 mg RE/L) and total carotenoids (0.048 mg/L) were observed with fructooligosaccharides addition. Isomaltooligosaccharides addition enhanced the antioxidant capacities of kiwi juice. Furthermore, the highest α-amylase inhibitory activity (68.22 %) was recorded in fermented clear kiwi juice supplemented with galactooligosaccharides, whereas fructooligosaccharides addition exhibited the most effective overall inhibition of pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium). Oligosaccharides supplementation facilitated the formation of ketone, especially for 2,3-butanedione and 3-hydroxy-2-butanone identified as the predominant ketones. Pearson's correlation analysis revealed a significantly positive correlation between total alkaloid content and α-amylase inhibitory activity.