Lactic acid fermentation of Arthrospira platensis for the production of a new lactose-free beverage rich in probiotics

The first objective of this study was to evaluate the use of lyophilised biomass of the cyanobacterium Arthrospira platensis F&M-C256 in a “vegetal soybean drink” (Alce Nero), as substrate for lactic acid fermentation by Lactobacillus plantarum ATCC8014 (LAB8014) and to evaluate the fermented products in terms of probiotic bacteria content, biochemical composition, in vitro digestibility (IVD), in vitro antioxidant activity (IVAA), and total phenolics (TP), which are considered parameters of great importance for the development of probiotic and functional beverages. The suitability of A. platensis biomass as substrate for LAB8014 growth was tested according to Niccolai et al. (2019). After 72 h of fermentation, the LAB8014 concentration was 10.5 log CFU mL−1 and lactic acid and acetic acid concentration reached 1.2 and 7.7 g L−1, respectively. As expected, after 72 h of fermentation a decrease of pH (-8%) and carbohydrates (-25%) was observed. Lyophilised A. platensis biomass was shown to be a suitable substrate for LAB8014 growth. After fermentation, the lyophilized broth contained 51% of proteins and 23% of lipids. IVD, IVAA and TP increased (+2%, +31%, and +30%, respectively), while phycocyanin content decreased (-23%). The in vivo antioxidant activity of the lyophilized broth (after 72 h fermentation) was also measured using a Saccharomyces cerevisiae ZIM2155 model. An aqueous extract prepared from the lyophilized broth was able to strongly reduce intracellular oxidation processes in the yeast cells. This study highlights the potential of A. platensis F&M-C256 biomass as a substrate for the production of lactose-free vegan beverages rich in probiotics.