Comparative analysis of LAB and non-LAB fermented millet drinks fortified with Chlorella sp.

Abstract

This study investigates the expanding domain of functional beverages crafted from plant-based milk alternatives. In this study, a total of eight different fermented drinks fortified with beneficial Chlorella sp. and probiotics including Lactobacillus rhamnosus (NCIM 5775) and Saccharomyces cerevisiae (Brewer's yeast) drinks were developed using barnyard millet as the base ingredient due to its rich protein and high-fibre content in comparison with the other millets in the market. Results revealed that the protein content increases by 2% upon the addition of Chlorella sp., among bacterial samples, with Lactobacillus rhamnosus fermented Unflavoured drink (LRFFD) > Lactobacillus rhamnosus fermented flavoured drink > Lactobacillus rhamnosus fermented with Chlorella sp. > LRFM, and among yeast samples, with Saccharomyces cerevisiae fermented Unflavoured drink (SCFUFD) > Saccharomyces cerevisiae fermented with Chlorella sp. > Saccharomyces cerevisiae fermented flavoured drink (SCFFD) > SCFRM, indicating higher protein content than in typical fermented drink. Fat content was notably low across all samples. Ash and fibre content ranged from 0.23 to 0.27 g and 0.22 to 0.35 g, respectively, for both bacterial and yeast fermented drink. Millet is generally considered a carbohydrate-rich grain. When fermented, some of the carbohydrates may be broken down by the fermentation process. So, the carbohydrate content was low in fermented millet drink when compared to the nonfermented drink. Energy values varied, with LRFFD and SCFFD containing the highest energy due to incorporation of Chlorella sp. and chocolate flavour. Both LAB and yeast-fermented drinks demonstrated effective antioxidant activity, with higher total phenolic content, except for non-Chlorella sp. beverages. GC-MS analysis identified constituents like hexadecenoic acid and hydroxy methyl furfural (HMF) with anticarcinogenic and anti-inflammatory properties. Additionally, these samples exhibited elevated antimicrobial activity against test strains. Sensory analysis indicated a preference of SCFFD and LRFFD sample for its good taste as it contains chocolate flavour and the overall acceptability of bacterial fermented beverage was higher compared to the yeast fermented drinks. Therefore, a fermented millet beverage was successfully obtained by the coculture of LAB and Saccharomyces cerevisiae incorporated with Chlorella sp. could increase the product's functional properties.