Modifications of the volatile and nonvolatile metabolome of goat cheese due to adjunct of non-starter lactic acid bacteria

Abstract

The aim of this work was to evaluate the impact of the addition of two lactic acid bacteria (LAB) strains, namely Lactobacillus casei-VC199 and Enterococcus lactis-BT161, on the composition of goat cheese at 30 and 60 d of ripening. In the metabolite and lipid profiles, as determined by 1H NMR spectroscopy, we found the primary products of lipolysis: free fatty acids (FFA) and diacylglycerols; of glycolysis: organic acids; and of proteolysis: free amino acids (FAA). The cheese volatilome, monitored over the ripening period by SPME-CG-MS, indicates the mechanism by which these primary metabolic products are converted to flavor compounds. Principal Component Analysis (PCA) suggests that the two LAB strains differently affect the metabolite and volatile compound content of the cheeses, the difference being the greatest at 60 d of cheese ripening. Cheese produced with Lb. casei had greater quantities of FAA, FFA, and organic acids than E. lactis cheese. The volatilome of samples inoculated with E. lactis was characterized by higher ketone content, while Lb. casei produced more acids and esters. The results of this work highlight the potential and complementarity of NMR and SPME-GC-MS analytical techniques to investigate the impact of LAB on cheese compositional characteristics.