Assessing the proteolytic and lipolytic activities of single strains of mesophilic lactobacilli as adjunct cultures using a Caciotta cheese model system

Abstract

Abstract Seventeen strains of mesophilic lactic acid bacteria, isolated from cheese (non-starter lactic acid bacteria, NSLAB) or sourdough, were used individually as adjunct cultures in a Caciotta cheese model system. Adjunct cultures were monitored by randomly amplified polymorphic DNA analysis and their cell counts mainly varied from ca. 9.0 to 8.0 log cfu g−1 throughout 36 days of ripening. Adjunct cultures influenced differently cheese proteolysis. Both NSLAB and sourdough strains caused an extensive secondary proteolysis; however, some NSLAB strains produced the highest concentration of free amino acids. Principal component analysis (PCA) differentiated cheeses manufactured with NSLAB strains Lactobacillus parabuckneri B9FST, Lb. paracasei B61F5, Lb. curvatus 2768 and Lb. rhamnosus ATCC 7469 based on the accumulation of Lys, Glu, Phe, Hist, Asp and Met. Assessment of cheese lipolysis showed that: (i) highest concentrations of free fatty acids (FFA) were found with NSLAB strains Lb. rhamnosus ATCC 7469 and Lb. casei subsp. pseudoplantarum 2742 (ca. 10 500 mg kg−1); (ii) PCA differentiated cheeses manufactured with NSLAB strains Lb. rhamnosus ATCC 7469 and Lb. casei subsp. pseudoplantarum 2742 based on the accumulation of palmitic (C16:0) and linoleic (C18:2) acids, and those with Lb. curvatus 2768 and Lb. parabuckneri B9FST based on the high concentration of short chain FFA; (iii) the cheese made with sourdough strain Lb. sanfranciscensis CB1 had the highest levels of unsaturated FFA.