Anti-salmonella potential and antioxidant activity of fermented fruit-based juice by lactic acid bacteria and its biotransformation

Abstract

Background: Lactic acid bacteria-based fermentation clearly contributes to improving nutritional value and exhibits various health benefits. The demand for non-dairy functional beverages, such as fruit beverages, as an alternative vehicle for probiotics is increasing because of lifestyle choices or health conditions. Therefore, the objective of this study was to evaluate the anti-Salmonella potential and antioxidant activity of fermented fruit-based juice by lactic acid bacteria and its biotransformation.  

Methods: In this study, to produce the fermented fruit-based juice (FFJ), the mixed fruit juice (MFJ) was fermented by Lactobacillus plantarum and Lactobacillus salivarius for 72 hrs. The potential function, anti-Salmonella by the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibiofilm activities of FFJ against Salmonella Typhi DMST 22842 was evaluated. The antioxidative capacity was determined by DPPH and FRAP assay. The active volatile compounds were identified by GC-MS. 

Results: A novel functional FFJ showed excellent growth capacity with 8 log CFU/mL of probiotics Lactobacillus plantarum and Lactobacillus salivarius. MIC and MBC values in the FFJ were 500 mg/mL after 72 hrs of fermentation. After 48hrs of fermentation, biofilm formation inhibition was significant (p < 0.05) with 95.27% ± 2.26% inhibition; biofilm metabolic activity inhibition was also significant (p < 0.05) with 89.25% ± 0.18% inhibition. The volatile compounds present in the FFJ were fruity flavors and aromas, most of have antimicrobial and antioxidant properties.  These compounds comprise various classes, including alcohols, organic acid, ester, and ketone. In both LAB fermentations, the most abundant volatile alcohol was isoamyl alcohol, followed by 1-hexanol and 2,3-Butanolone; acetic acid was only present in L. plantarum fermentation. In addition, DPPH radical scavenging and FRAP assay showed the mixed fruit juice had dramatically increased antioxidant activity after 48 hrs of fermentation.

Conclusion: The findings of this work indicate that the obtained fermented fruit-based juice (FFJ) showed excellent growth capacity of probiotics, Lactobacillus plantarum and Lactobacillus salivarius, and produced the volatile compounds from biotransformation. This not only improved fruit flavor and aroma, but also influenced antibacterial activity against the pathogen Salmonella Typhi DMST 22842, as well as increased antioxidant activity. Therefore, the FFJ could be a novel functional fermented drink for vegan and non-diary consumption.

Keywords: Lactic acid bacteria, Probiotics, Biotransformation, Non-dairy functional beverage, Anti-Salmonella