Production of lactic acid from whey using Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus

Abstract

The main objective of this research was to determine the proper growth conditions of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus for the production of lactic acid using serum as substract. This serum was obtain from the department of Cesar, Colombia. Lactic acid is the result of the extraction and purification of fermentation broths in which bacteria Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus are used, which are usually used for the production of yogurt. The substrate was supplemented with yeast extract, ammonium phosphate as a nitrogen source, and calcium carbonate as a neutralizer, in order to optimize the consumption, by the bacteria, of the main carbohydrate present in serum (lactose). During the fermentation (up to 72 h) the inoculums concentration, and temperature were controlled. Purification consisted in esterification, filtration of solids formed during the reaction, and removing of water by evaporation and nitrogen influx. Finally, lactic acid was obtained with 78,0% purity (36.7 g/L), which was characterized by infrared spectroscopy

Keywords

• ácido láctico
• lactosuero
• bacterias acido lácticas
• Lactobacillus delbrueckii
• Streptococcus thermophilus