Investigation of kinetic model of phytic acid degradation and increase of calcium and zinc in single and co- culture of Lactobacillus plantarum and Lactobacillus acidophilus

Phytic acid is an anti-nutritional compound found in bran and whole wheat flour. In order to reduce the amount of dough medium, single and co- culture of two strains of Lactobacillus plantarum and Lactobacillus acidophilus with 4 sourdough formulations (Formula 1 containing S. cerevisiae yeast, Formula 2 containing L. acidophilus + S. cerevisiae, Formula 3 containing L. plantarum + S. cerevisiae and Formula 4 containing L. plantarum + L. acidophilus + S. cerevisiae) were used and fermentation was performed at 27, 32 and 37 ° C at 8, 16 and 24 h. The amount of phytase, phytic acid and minerals (calcium and zinc) were measured at different temperatures and time intervals. First order model reaction was used to investigate the degradation of acid phytic and the increase of calcium and zinc at different temperatures. The data were in good agreement with this model. Moreover, the corresponding activation energies were calculated. The results showed that co- culture of L. plantarum + L. acidophilus + S. cerevisiae represented the highest content of phytase 163 U/mL and the highest calcium 27.4 mg/100g and zinc 1.69 mg/100g (at 37 °C). Although the highest efficiency of phytase production was observed in the first 8 hours of fermentation, however an increasing trend was observed in the content of zinc and calcium up to 24 hours of fermentation. The trend of phytase production was observed as follows: L. plantarum + L. acidophilus + S. cerevisiae> L. plantarum + S. cerevisiae> L. acidophilus + S. cerevisiae> S. cerevisiae. Moreover, the lowest content of phytic acid was observed after 24 hours of fermentation at 37 °C in sourdough of L. plantarum + L. acidophilus + S. cerevisiae and its amount reduced from 563.8 ± 20.5 mg/100 g in wholemeal flour to 43.8-110.3 mg/100 g.