Hypoallergenic buckwheat flour preparation by Rhizopus oligosporus and its application to soba noodle

The effect of Rhizopus oligosporus on the structure and functional properties of buckwheat grain during fermentation was investigated and the production of buckwheat hypoallergenic flour was studied. The spores of R. oligosporus were mixed with steamed buckwheat grains, and they were incubated at 30 °C and 85% relative humidity (RH) for 0, 24, 48 and 72 h. The changes of structure, free amino acids, minerals, phytic acid and allergenic proteins in the grains were determined during the time course of incubation. The 48-h-fermented buckwheat (FeB) was found to be involved in formation of amino acids with higher amounts of total amino acids, and some of them increased 50 times more; including isoleucine, leucine, lysine, valine, glycine, histidine, tyrosine and γ-amino butyric acid (GABA). SDS–PAGE and Western Blot analyses showed that R. oligosporus was very effective to reduce allergenic proteins of buckwheat and could produce the hypoallergenic buckwheat flour. In its application to noodle making, the FeB-substituted wheat flour noodle was softer and had more elasticity than the control without FeB flours (1CW), except for the 10% substitution of FeB. Uncooked and cooked noodles were brownish compared to those of the 1CW. The R. oligosporus could possibly be used to produce hypoallergenic buckwheat with higher functional and good rheological properties, and thus produced FeB flour was considered to become a big prospect for development of new food in the future.