Effect of non-starter lactobacilli used as adjunct-culture in model cheese production on volatile compounds and free amino acid contents

Adjunct culture can be used to improve typical cheese aroma and contribute to proteolysis during the ripening process. In the present study, some lactobaczilli ( Lactobacillus casei, Lactobacillus delbrueckii subsp. bulgaricus, Lactiplantibacillus plantarum and two strains of Lactobacillus helveticus ) were tested in model cheeses during 120 days of ripening at the temperatures of 8 and 16°C. It aimed to investigate the effects of these parameters on free amino acid (FAA) content, volatile aroma profile, and sensory properties in cheese. Volatile compounds in cheese samples were determined by gas chromatography-mass spectrometry and FAA content by high performance liquid chromatography. Principal component analysis, sparse partial least squares-discriminant analysis, and heat map cluster analysis were performed to distinguish different volatile aromas and FAAs in cheeses according to ripening time and temperature as well as adjunct culture. The predominant FAAs in the cheese were Arg, Tyr, Val, Leu, Trp, and Lys, regardless of ripening. The highest concentration of Glu was observed in cheeses containing L. bulgaricus , followed by cheeses with L. helveticus and L. plantarum . A total of 41 volatile compounds were identified, with variations noted between the different cheeses; in particular, L. helveticus played a crucial role in flavor development. The ripening temperature also influenced the production of volatile compounds: at 16°C, cheeses with L. bulgaricus and L. helveticus were characterized by alcohols, esters, and acids, while cheeses with L. plantarum contained mainly, acids, aldehydes, and ketones. For lactobacilli, especially the combination of L. helveticus, L. bulgaricus , and L. plantarum , can be added to the cheese to improve and intensify the flavor. It was seen that the positive effects of selected adjunct cultures on the aroma and taste of model cheeses were related to volatiles and FAAs.