Optimization of growth of Lactobacillus casei ASCC 292 and production of organic acids in the presence of fructooligosaccharide and maltodextrin

Abstract

Growth of Lactobacillus casei ASCC 292 was optimized in the presence of 2 prebiotics, namely fructooligosaccharide (FOS) and maltodextrin, and the patterns of organic acids produced was monitored. Perturbation plot, response surface, and coefficient estimates showed that inoculum size and concentration of prebiotics had significant quadratic effects on growth, with FOS showing the most prominent quadratic change. The second-order polynomial regression model estimated the optimum inoculum size and the concentrations of FOS and maltodextrin for the growth of L. casei ASCC 292 to be 1.67% w/v, 4.82% w/v, and 6.93% w/v, respectively. Validation experiments showed that the predicted optimum condition was better than the high and low levels of the factors, and at center points. Response surface methodology (RSM) was reliable in developing a model, optimizing factors, and analyzing interaction effects. Analysis of individual organic acids production by L. casei ASCC 292 showed that highest amount of lactic acid was produced, followed by propionic, acetic, formic, and butyric acid. The production of lactic acid was greatly influenced by the inoculum size, and the organism was relatively sensitive to the end-product of maltodextrin fermentation. Production of acetic acid was greatly influenced by the inoculum size and was inhibited by end-product of the maltodextrin fermentation. Increased concentration of FOS contributed to the increased production of propionic acid. The response surface of butyric and formic acid showed that the production of these acids were growth associated. © 2005 Institute of Food Technologists.