Evaluating the potential effect of microalgae on soymilk vegan kefir in terms of physical, chemical, microbiological properties

The demand for functional fermented plant-based milk products has intensively increased. Here, the physical, biochemical and microbial consortia of two different kefir samples which are soymilk kefir (S) and cows' milk kefir (M) was evaluated and examination of nutritional and microbial value of adding Haematococcus pluvialis microalgae to soymilk kefir at a ratio of 0.25 % (S1) and 0.50 % (S2) was done in order to fulfill deficiencies caused by the lack of animal-based milk. As part of a functional comparison between the two samples, besides physicochemical and biochemical analysis, the structure and functional diversity of the bacterial communities was also evaluated by metagenomic analysis. S1 and S2 kefir samples presented significantly increased pH, protein, fatty acid index and decreased fat content than the M sample. It was also observed a high bacterial diversity in S1 and S2 kefir samples including greater abundance of Leuconostoc lactis (31.98 %), Lactococcus lactis (23.68 %), Leuconostoc mesenteroides (19.72 %); Liquorilactobacillus nagelii (32.70 %). Moreover, the increased concentration of H. pluvialis in S1 and S2 kefirs resulted in reduction of the abundance of Bacillus cereus. It can be concluded that microalgae biomass can be used as an innovative natural ingredient to develop fermented, functional, vegan and lactose-free kefir with high nutritional and bio-diversified options. [Display omitted] •Microalgae biomass results in innovative products for vegan and lactose-intolerant consumers.•Microalgae-derived soymilk kefir offers enhanced nutritional and microbiological properties.•Microalgae fortification promotes proliferation of Leunocostoc, Liquorilactobacillus and Lacticaseibacillus.•Microalgae fortification fulfils the nutritional properties that may occur due to animal milk deficiency.