Volatilome changes during probiotic fermentation of combined plant-based drinks
Plant-based drinks as a substitute for animal milk consumption are crucial products in the food industry. Soy and rice drinks are the most successful milk substitutes but are low in fiber and protein contents, respectively, whilst rich in sugars. Generally, an improvement is foreseen; thus, apart from supplements addition, a natural occurring strategy is functionalizing the drinks by beneficial bacteria fermentation. The aim of this work is to develop novel plant-based drinks assessing different mixtures of soy and rice milks fermented with single or multi-strains probiotics (Lactobacillus fermentum, L. plantarum, L. helveticus, Bifidobacterium bifidum, and B. longum). The drinks were characterized to study bacterial performances, by means of culture-dependent and -independent techniques, and their volatilome, by means of solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis. Through multivariate analysis, these features were investigated and correlated to define accurate descriptors of the produced functional drinks. The results showed that combined drinks and multi-strains fermentation generated higher-value products. For example, blended drinks in comparison to single ones had lower amount of toxic 2-acetyl-3,5-dimethylfuran and higher abundances of desirable compounds as 2-butanone, 3-hydroxy and butanoic acid. Multivariate analysis of volatile metabolites and physiological parameters could offer a novel approach to assess the quality of functional plant-based drinks and result in a decisional tool for industrial applications.