Ardestani F. نويسنده Assistant Professor of the Department of Chemical Engineering, Qaemshahr Branch , Rezvani F. نويسنده M. Sc. Student of the Department of Chemical Engineering, Shahrood Branch , Najafpour G. D. نويسنده Professor of the Department of Chemical Engineering
ABSTRACT: Lactic acid production in a batch submerged fermentation process by five Lactobacilli: bulgaricus, casei, lactis, delbrueckii and fermentum in lactose fortified whey culture were investigated. Kinetic behavior of Lactobacilli growth rate and lactose utilization was studied based on the Moser and Gompertz kinetic models. Trendline tool in Excel software was applied for fitness assessment of the experimental data to investigate the kinetic models. Lb. bulgaricus had shown the best cell production yield of 0.119 g.g-1 of consumed lactose. Also, maximum lactic acid production yield of 0.602 g.g-1of consumed lactose was obtained by Lb. bulgaricus. Lb. bulgaricus (R2=0.954, ?max=0.5 and Ks=9.385) and Lb. casei (R2=0.956, ?max=0.580 and Ks=18.2) have showen acceptable consistency with Moser kinetic model. Moser kinetic model isnʹt a desired model to describe the cell growth and substrate consumption behavior of Lb. fermentum, Lb. delbrueckii and Lb. lactis. None of the investigated strains have shown acceptable consistency with Gompertz kinetic model, therefore, this model isnʹt known as a good model to describe the cell growth and substrate utilization behavior of Lactobacilli.