Antioxidants in heat-processed koji and the production mechanisms

We previously developed antioxidative heat-processed (HP)-koji via two-step heating (55 °C/2 days → 75 °C/3 days) of white-koji. In this study, we isolated antioxidants in HP-koji and investigated their formation mechanisms. The antioxidants were identified to be 5-hydroxymethyl furfural (HMF) and 5-(α-d-glucopyranosyloxymethyl)-2-furfural (GMF) based on nuclear magnetic resonance spectral analysis. HMF and GMF were not present in intact koji,...