Production of lactic acid by Lactobacillus acidophilus LA5 and Bifidobacterium lactis BB12 in batch fermentation of cheese whey and milk permeate

Lactic acid (2-hydroxyproponic acid) is an important organic acid with widespread applications in the food, pharmaceutical, detergent and agricultural industries. For this purpose, the effects of nutrients and important environmental factors on the production of lactic acid using the by-product of dairy plants (cheese whey and milk permeate) as a culture medium with pure culture of Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12 were investigated. The results of statistical analysis of the data showed a significant effect of initial pH, incubation temperature, yeast extract concentration, type of culture medium and type of bacteria on lactic acid production (p <0.05). The incubation time, type of probiotic bacteria and yeast extract concentrations had a significant effect on cell density (p < 0.05). As well, the effect of initial pH, temperature and incubation time, yeast extract concentration, culture medium and probiotic bacteria on pH were significant (p < 0.05). Although the results of this study showed that milk permeate and cheese whey due to their high content of lactose can be a suitable medium for the production of lactic acid, the cost of using supplements, especially the nitrogen source, is essential.