Abstract: Due to the lack of effective monitoring parameters for anaerobic lactic acid fermentation process, it is difficult to observe the change in physiological status of lactic acid bacteria during the fermentation process. Oxidoreduction potential (ORP) can reflect the status change of anaerobic lactic acid fermentation system. In this study, the optimal addition concentration and time of corn syrup were explored through the evaluation of ORP change. Results indicated that the optimal addition concentration and time of corn syrup were 0.5% and 30 h, respectively. The addition of corn syrup could effectively regulate carbon-nitrogen ratio during the late stage of fermentation and maintain a beneficial reducing environment for lactic acid synthesis, which resulted in a 20% enhancement of lactic acid production. Therefore, ORP can be a monitoring parameter of lactic acid fermentation process, and corn syrup can modulate the ORP during fermentation process.

Key words: lactic acid, pH feedback feeding, oxidoreduction potential (ORP), corn syrup