Abstract: Using selenium-rich pear as the main fermentation material, bran as auxiliary material, and yeast as fermentation strain, the chemical analysis was used to monitor the fermentation process dynamically. The results showed that the pH, COD and electrical conductivity in the fermentation broth experienced a process of rapid change in the early stage, relatively stable in the middle stage and obviously changed in the later stage. The total nitrogen had been in a stable and fluctuating state during fermentation. The fertility of the final fermented product was compared with the relevant national and industrial standards, and the results were satisfactory. Different carbon and nitrogen ratios had certain effects on the rate of fermentation. The dynamic monitoring results combined with the visual observation suggested that the floating phenomenon of the fermentation residue could be used as a convenient and operable endpoint determination in the field.

Key words: selenium-rich pear, bran, yeast fertilizer, dynamic monitoring, fermentation process