Fermentation of blueberry slurry by lactobacilli strains: Investigation on soluble and insoluble fractions

This study investigated the fermentation of blueberry slurry by Lactiplantibacillus plantarum and Limosilactobacillus fermentum, focusing on three fractions: soluble components in the juice, soluble components adhered to the pomace, and insoluble components within the pomace. Soluble components including sugars, organic acids and phenolics were consistently retained on the blueberry pomace throughout fermentation. Meanwhile, lactic acid fermentation induced irregular changes in the pectin composition of the extracted blueberry cell wall materials (B-CWM) and weakened B-CWM's ability to adsorb free phenolics. After 30-min adsorption in fresh blueberry juice, the adsorption capacity of B-CWM extracted from blueberry pomace fermented by both strains for 48 h were declined by over 50%, compared to unfermented B-CWM. Moreover, significant correlations between microbial activities and pomace physicochemical properties suggest the certain influence of blueberry pomace on the lactic acid fermentation process. These findings provide new insight into how fruit pomace modulates microbial fermentation and phenolic retention.