Effects of Fermentation Temperatures on the Qualities of Monascus sp. PSRU03 Fermented Soybeans

This research evaluated the effects of fermentation temperatures on the qualities of soybeans fermented with Monascus sp. PSRU03. The conditions included consistent temperatures of 25°C for 20 days, 30°C for 20 days, and a cyclic pattern of 30°C for 4 days followed by 25°C for 16 days. The pigments and antioxidant properties of the fermented soybeans were evaluated. After fermentation, it was observed that the total pigment contents exhibited similarity across all conditions, with values ranging from 31.90 to 35.67 unit/g dry basis. Notably, Monascus sp. PSRU03 produced more yellow pigment than other colors, accounting for approximately 50-53%, which corresponded to a range of 6.94-14.31 unit/g dry basis. This phenomenon is distinctive in that the majority of industrially manufactured Monascus pigments are rich in red pigments. In terms of antioxidant properties, fermentation at 30°C produced the highest total phenolic compounds (6.10 mg GAE/g dry basis). However, DPPH radical-scavenging activity and ferric reducing antioxidant power were found to be not significantly different (P≥0.05) in all fermentation temperatures. These findings provide a foundation for optimizing industrial fermentation processes and exploring the health benefits of Monascus-fermented soybeans.