The kinetics of dephosphorylated phytic acid release from enzymatic hydrolyzed Red Kidney Beans (Phaseolus vulgaris L)

Abstract.

Enzymes are capable of hydrolyzing phytic acid hence dephosphorylate in legumes. This process reduces the phytic acid content and while liberating phosphorus. Enzymes such as phytases are used as additives in animal feeds and also in breads to increase the bioavailability of nutrients. A red kidney bean (RKB) is a legume that contains important nutrients with great potential which could confer significant health benefits, because of the antinutrients that inhibit the bioavailability of important nutrients. In this study, the RKB was hydrolyzed in water and buffer solution spiked with the Maxamyl phytase enzymes for the purpose of dephosphorylating phytic acid thus releasing the inorganic phosphorus and other minerals. The RKB was hydrolyzed in two mediums (buffer and distilled water) at concentrations of 0, 200, and 400 FTU phytase units for 0, 3, 6, 9, and 24 h. Samples were collected intermittently and freeze dried and grounded for enzyme assay. The result shows the concentration of enzyme significantly (p < 0.001) affect the enzymatic activity, hence the highest activity was observed at 126.45 FTU/g for RKB hydrolyzed in a buffer solution with Maxamyl concentration of 200 FTU. Furthermore, significant (p<0.001) increase in the release of phosphorus (1.77 µM/g) was also observed in the buffer medium with the Maxamyl concentration of 200 FTU. The rate of phosphorus released was higher in the buffer medium than the distilled water. Hence, the release kinetics were 0.0049, 0.007, 0.0033/hr in buffer medium at Maxamyl concentration of 400, 200, and 0 FTU, respectively. Also, an increase in enzyme activity is correlated to the dephosphorylation of phytic acid; hence evident of the release of phosphorus from the phytic acid bond. The incubation time also was noted to significantly (p<0.001) impact the release kinetics. The study shows that food grade enzymes have great potential application in increasing the nutritional potential of processed RKB. This could help in improving the bioavailability of nutrients in legumes. In conclusion, enzyme hydrolyzed red kidney beans can be a convenient and value added product if produced commercially.