Lactobacillus adjuncts in cheese: Their influence on the degradation of citrate and serine during ripening of a washed curd cheese

Lactobacillus adjuncts, differing in metabolic properties, were evaluated in a washed curd, brine salted Dutch-type cheese during long term ripening. Two different adjuncts were used; Lb. plantarum INF15D degrading serine (Ser) and citrate and possessing glutamate dehydrogenase (GDH) activity and Lb. paracasei ssp. paracasei INF448 with only a weak ability to degrade citrate. Lb. plantarum INF15D degraded residual citrate in cheese to aspartate (Asp). Early during ripening, Asp was degraded to acetoin most probably when the cells were in a growing state. Degradation of Ser by Lb. plantarum INF15D contributed to the production of formate and succinic acid in the early stage of ripening, while acetate was produced during later ripening. Lb. paracasei ssp. paracasei INF448 produced lactate from residual citrate and did not degrade Ser or Asp in the cheese.