Experimental studies of cheese prefermentation; a mathematical model reflecting the pH effect

The cell growth and lactic acid production rates are important factors that determine the quality of cheese in the cheese fermentation. Therefore, a m athematical model that can predict the cell dynamics and lactic acid produc tion is expected to play an important role in process improvement. A batch fermentation model of Lactococcus taking into account the effect of pH was developed in this paper. Since the substrate (lactose) concentration remain s high and the product (lactic acid) concentration is very low in the prefe rmentation of cheese, the effects of lactose and lactic acid concentrations are negligible on kinetics. However, the specific rates vary greatly with the pH. In industrial practice the pH is uncontrolled and therefore decreas es with time as lactic acid is produced. Therefore, the pH dependence of ki netic parameters must be incorporated in the model. The proposed model simu lates uncontrolled pH experiments well.