Increasing the fermentation efficiency of Lactobacillus paracasei ssp. paracasei MIUG BL6 in a rye flour sourdough

Background: The present study reports the optimization of the biotechnological conditions in order to improve the lactic acid fermentation process, in a rye flour medium by using Lactobacillus paracasei ssp. paracasei strain, coded MIUG BL6, as a starter culture. Materials and methods: A sequential statistical methodology, comprised of Plackett-Burman experimental design, central composite design and response surface methodology, was applied to enhance the lactic acid fermentation productivity. Results and discussion: Among the tested parameters, the milk powder and KH2PO4 concentration and also the time of fermentation were identified as the most significant variables that influence the fermentation process. The optimum levels of these significant parameters were determined as follows: 4.21% milk powder, 0.30% KH2PO4 and 48 h of fermentation that induced an increase of 1.6 fold of the acidity, compared to the fermentation conducted under the non-optimized conditions. Also, under these optimized fermentation conditions, a good rate of cell multiplication of 10.19 log N/N-0 was achieved.