PHYTATE DEGRADATION IN WHEAT, BUCKWHEAT, SOY, AND RICE FLOURS BY LACTOBACILLI AND YEAST ISOLATED FROM AFRICAN AND ASIAN TRADITIONAL FERMENTED FOOD

Phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphosphate) is a phosphorus reservoir found especially in cereals, legumes, and oilseeds. This compound forms complexes with essential minerals such as K, Mg, P, Ca, Fe, Zn, and Mn, thus reducing their bioavailability. Therefore, due to its negative impact on intestinal mineral absorption, phytic acid is considered an antinutritional substance, as it can modify functional characteristics in food proteins. In seeds, the aleurone layer contains approximately 90% of the grain's phytic acid, with the germ holding about 10%. Consequently, flours, especially those from whole grains, are rich in phytic acid. Therefore, increasing the use of bran and whole wheat flour in food formulations may compromise the nutritional quality of end products by limiting mineral bioavailability. Microbial fermentation has been described as a strategy to reduce the adverse effects of phytic acid in food products. The present work aimed to thoroughly investigate the impact of different yeasts and lactic acid bacteria, isolated from Asian and African traditional fermented foods, on different flours (wheat, buckwheat, rye, and soy flours) and doughs prepared with selected cereal meals on the levels of phytate during fermentation and breadmaking. Eleven yeasts belonging to Pichia kudriavzevii, Saccharomyces cerevisiae, Pichia fermentans, and Kluyveromyces marxianus and two lactobacilli belonging to Lactiplantibacillus plantarum and Lacticaseibacillus paracasei have been selected. The comparison of selected yeasts and lactobacilli in the degradation of phytic acid with different flours as substrates (wheat, buckwheat, soy, and rice) showed that the degradation ranged from 16 to 77%. The best-performing strain resulted in P. kudriavzevii TY1322 with 77% of phytic acid degradation. The degradation of phytate for bread production using single yeast was 52.06% ± 4.25, while when a mixed inoculum yeast-lactobacilli was used, the degradation improved up to 60,02% ± 0.21. Lactobacilli can achieve a strong phytic acid degradation both by lowering pH and providing more suitable pH conditions for phytate degradation by endogenous phytases and by a direct source of microbial phytases. Since the potential benefits of bread incorporating various grains (e.g., soy, buckwheat, and rye) are increasingly evident, this research could have an important implication for human health.