Pyruvate stimulates transamination of leucine into α-ketoisocaproic acid and supports 3-methylbutanal production by Lactococcus lactis.

Aim: To investigate the effect of pyruvate and glucose on leucine transamination and 3-methylbutanal production by Lactococcus lactis, including the comparison with cells possessing glutamate dehydrogenase (GDH) activity.

Methods And Results: Lactococcus lactis cells were incubated in chemically defined medium (CDM) with the pH controlled at 5.2 to mimic cheese conditions.

Contribution of the novel sulfur-producing adjunct Lactobacillus nodensis to flavor development in Gouda cheese.

We assessed the efficacy of Lactobacillus nodensis CSK964 as an adjunct culture in Gouda cheese under various industrial conditions. We set up 4 different systems: a direct vat inoculum with and without adjunct using the calf rennet Kalase, and an undefined bulk starter culture with and without adjunct using the microbial rennet Milase (both rennets from CSK Food Enrichment, Ede, the Netherlands). During ripening, we subjected the cheeses to the following analyses: viability of starter and adjunct cells, composition, proteolysis, and flavor development by detection of sulfur compounds and descriptive sensory analysis.

NoxE NADH oxidase and the electron transport chain are responsible for the ability of Lactococcus lactis to decrease the redox potential of milk.

The redox potential plays a major role in the microbial and sensorial quality of fermented dairy products. The redox potential of milk (around 400 mV) is mainly due to the presence of oxygen and many other oxidizing compounds. Lactococcus lactis has a strong ability to decrease the redox potential of milk to a negative value (-220 mV), but the molecular mechanisms of milk reduction have never been addressed.