Storage temperature and quality changes of natto

Storage conditions significantly affect the quality of natto, a fermented soybean food produced with Bacillus subtilis (natto). We investigated relationship between natto and storage temperature. Manufactured samples were stored at 5–20 °C for 20 days, on every 5th day we evaluated following: 1) viable bacterial number, 2) ammonia nitrogen, 3) free amino acids, 4) gamma-polyglutamic acid (γ-PGA), 5) hardness, 6) color grains. During storage, products exhibited damage, especially when °C. Natto scored based these indicators, 5 10 days or had similar scores. Overseas export is gradually increasing. The score proposed in this study basic indicator that can be used to rule out inferior products, will help grow market worldwide facilitate distribution through cold chain.