Production of lactic acid from cheese whey by batch cultures of Lactobacillus helveticus

Abstract

The production of lactic acid by Lactobacillus helveticus from a cheese whey residue obtained from a dairy was investigated. Batch fermentation experiments showed that the optimal temperature to carry out the process was 42°C and the optimum pH was 5.9, giving at these conditions a maximum concentration of lactic acid of 53 g/l. The addition of yeast extract to the cheese whey residue as a nitrogen source for L. helveticus did not increase the lactic acid production significantly. The results obtained in this work confirmed that it is possible to increase the value of residues from the dairy industry for the production of value-added products such as lactic acid, which has important industrial applications. Also, the effect of the addition of a nitrogen source to the culture media of the fermentation experiments did not present a costbeneficial improvement on lactic acid production as other authors have shown. The last finding could reduce the cost of the culture media used for lactic acid production when scaling up the process.

Repeated-Batch Fermentation of Cheese Whey for Semi-Continuous Lactic Acid Production Using Mixed Cultures at Uncontrolled pH

“…The adoption of a repeated-batch feeding strategy, which was different from the start-up phase, strongly affected the lactic acid concentration and yields. In industrial-scale applications, lactic acid is generally produced in batch mode, and by using pure cultures, whose growth is optimised by the addition of a significant amount of chemicals [13]. Previous studies demonstrate that the adoption of a repeated-batch mode could give a higher yield than the adoption of a single-batch mode [10,23,30].…”

“…Different studies demonstrate that the optimum pH value for lactic acid production is between 5.5 and 5.9 [13,39,40]. The adoption of lower values led to low lactic acid concentrations (below 5 g/L) [14,31,38].…”

“…This result is highly relevant, as uncontrolled pH conditions are usually unfavorable for lactic acid production. Perez et al [13], for instance, studied CW fermentation by Lactobacillus helveticus under uncontrolled pH conditions in batch mode. The maximum observed concentration value was about 15 g/L, while the same species was able to accumulate around 60 g/L at a fixed pH of 5.9, and 80 g/L with the supplementary addition of yeast extract.…”

“…For this, CW can serve as an excellent feedstock for the production of lactic acid. However, several previous studies have been carried out on pure cultures under axenic conditions [12][13][14][15]. To the best of our knowledge, only a few studies used a mixed-culture inoculum and complex substrates as a fermentation feedstock [16,17].…”

“…The aim of this paper is to assess dark fermentative lactic acid production using CW mediated by mixed cultures. Among other biological conversion technologies, DF is considered to be particularly interesting, as it allows for the production of multiple biofuels and other platform chemicals from waste biomasses [10][11][12][13][14]. The study also aims at maximising the lactate yields along with identifying the optimal process stability at the natural pH of the substrate.…”