Erythritol in miso and rice koji is produced by koji mold

Sugar alcohols in various miso were analyzed using high-performance liquid chromatography to consider the relationship between miso and erythritol content. A Ca2+-type ligand exchange chromatography column was selected to separate sugar alcohols, particularly erythritol, in 16 miso samples. Erythritol was measured in almost all miso samples (0.208–3.50 mg/g-miso), and high concentrations of erythritol were detected in low-salt rice miso (sweet type miso, 2.12–2.85 mg/g-miso). The highest erythritol content was observed in soybean miso (3.50 mg/g-miso). Glycerol was identified in all miso samples (1.77–10.4 mg/g-miso). Erythritol in rice koji prepared at 35 °C and 95 % relative humidity was 8.05 mg/g-dry koji. The theoretical concentration of erythritol was calculated as 2.82 mg/g-miso for sweet type miso manufactured using rice koji with the highest erythritol content. The erythritol in sweet type miso may originate from koji mold, which has important implications for the production of fermented foods.