Degradation of anti-nutritional factors and reduction of immunoreactivity of tempeh by co-fermentation with Rhizopus oligosporus RT-3 and Actinomucor elegans DCY-1

The effects of solid-state fermentation with four filamentous fungi (Rhizopus oligosporus, Actinomucor elegans, Neurospora crassa and Rhizopus oryzae) and their combination on the degradation of protein allergens and anti-nutritional factors (ANFs) of tempeh were evaluated. Glycinin, beta-conglycinin, trypsin inhibitor and flatulence-causing oligosaccharides were significantly hydrolysed by all assayed strains but the level of reduction of ANFs depended on the strain. ELISA was conducted to evaluate IgE immunoreactivity using sera from soy sensitive individuals. Results revealed that co-fermentation of R. oligosporus and A. elegans resulted in the highest reduction in IgE immunoreactivity for all sera used and showed greatest degradations on alpha', alpha, beta, acidic subunits (100% hydrolysed) and extensive hydrolysis of flatulence-causing oligosaccharides. Tempeh fermented with R. oligosporus and A. elegans displayed high level of soluble protein and peptide (<10 kD) content. Co-fermentation of R. oligosporus and A. elegans was proved to be effective in producing hypoallergenic tempeh.