Brewer’s spent grain as raw material for lactic acid production by Lactobacillus delbrueckii

Chemically pre-treated brewer’s spent grain was saccharified with cellulase producing a hydrolysate with approx. 50 g glucose l−1. This hydrolysate was used as a fermentation medium without any nutrient supplementation by Lactobacillus delbrueckii, which produced L-lactic acid (5.4 g l−1) at 0.73 g g−1 glucose consumed (73% efficiency). An inoculum of 1 g dry cells l−1 gave the best yield of the process, but the pH decrease affected the microorganism capacity to consume glucose and convert it into lactic acid.