Correlation of Some Substrate Parameters in Growing Lactobacillus acidophilus on Vegetable and Fruit Cocktail Juices

Using Lactobacillus acidophilus stains is a challenge in producing lactic acid fermented vegetable and fruit juices. There were analysed the correlation between the most important physico-chemical parameters of the substrate and the bacterial biomass accumulation in two vegetable and fruit juices. The data were collected during a 48 hour lactic acid fermentation using usually chemical and microbiological methods. There was analysed the correlation between the reducing sugar content and the lactic acid production, the correlation between the pH and lactic acid production, the correlation between the reducing sugar of the substrate and the microbial biomass accumulation and also between the lactic acid production and biomass accumulation. These correlations were analysed using simple regression on scatter plots. They were best fitted by the polynomial equation where the highest R2 were calculated. The two last correlations had large differences between the two experimental batches so that regression is not satisfactory to describe them. If all parameters were considered using the multiple regression, the correlation had a medium value because the cell multiplication of the bacteria Lactobacillus acidophilus in vegetable and fruit juices is influenced by many other environmental parameters. These had a large influence because juices are not the natural medium for this kind of lactic acid bacteria.