Effect of lactic acid bacteria and yeast fermentation on antimicrobial, antioxidative and metabolomic profile of naturally carbonated probiotic whey drink

The present study investigated the effect of lactic acid bacteria and yeast fermentation on development of a naturally carbonated probiotic whey drink using indigenous probiotic Lactobacillus plantarum MTCC 5690 and Kluyveromyces lactis NCDC 257. The CO2 level reached to 57.0 ± 6.12 mL/40 mL whey with concomitant increase in headspace CO2 level from 2.2 to 68.7 percent after 24 h of incubation. The drink was shelf stable and organoleptically acceptable for a period of 21 days under refrigeration, with probiotic count of ≥ 108 cells/mL. The total phenolics, FRAP and DPPH activity of fermented drink was significantly higher (P < 0.05) than the unfermented whey. L. plantarum exhibited antagonistic activity against all pathogens via radial streak assay. However, cell free supernatant of drink exerted mostly K. lactis mediated antimicrobial activity with highest and lowest inhibition against E. coli (28.0 ± 0.41 mm) and S. aureus (16.67 ± 3.86 mm), respectively. Untargeted metabolomics profiling through gas chromatography mass spectrometry revealed 58 metabolites. Some of differential flavour and nutritional metabolites observed in co-cultured whey were propan-2-ol, hexanoic acid, ethyl propionate, erythritol etc. The developed whey drink is ready-to-serve (RTS) and can be easily incorporated by industrial stakeholders in their production lines, thereby minimizing effluent volume and treatment cost.