MICROBIAL PHYTATE DEGRADATION IN SOY MILK FERMENTED PRODUCTS

Due to the rising incidence of dairy intolerance and the growing popularity of vegan/vegetarian diets, there is an increasing need for alternatives to dairy products. One commonly employed substitute in vegetarian and vegan food items is soybean, known for its mineral and protein content. However, soybean can contain antinutrient such as phytate (inositol hexaphosphate, IP6), which limits the absorption of nutrients. Microbial phytases, enzymes that hydrolyze phosphate groups from IP6, have gained considerable attention in solving this issue. The breakdown of IP6 by these enzymes releases chelated minerals like Fe and Zn and solubilizes IP6, thereby enhancing the availability of minerals for intestinal absorption. The objective of this study was to assess 10 strains of Lactic Acid Bacteria (belonging to Lacticaseibacillus paracasei, Lactobacillus delbruecki subsp. delbruecki, Lactobacillus helveticus, and Lactiplantibacillus plantarum) and 22 yeasts (previously isolated from Tajikistan yogurt and togwa, a Tanzanian traditional fermented cereal- and cassava-based product). The study aimed to evaluate their ability to ferment soy milk, individually or in mixed cultures, and their phytase activity. All strains belonging to Lacticaseibacillus paracasei showed the ability to ferment soy milk and thicken the resulting product. Kluvieromyces marxianus and Pichia kudriavzevii were identified as suitable candidates among the yeasts. The strong phytate-degrading ability previously observed in vitro for P. kudriavzevii TY1322 was confirmed during soy milk fermentation. Furthermore, the phytate degradation was enhanced when P. kudriavzevii TY1322 was co-cultured with Lacticaseibacillus paracasei AB3 and K. marxianus AL3 or BL8. These findings suggest that these strains are promising candidates for phytate degradation in the fermentation of soybased food products.