Technological characteristics of Lactobacillus spp. isolated from Iranian raw milk Motal cheese

Abstract Lactobacilli produce large amounts of bioactive metabolites, which makes them suitable for numerous technological applications. The objective was to evaluate the technological characteristics of 16 Lactobacillus isolates from Iranian raw milk Motal cheese, including acidifying ability, production of extracellular polysaccharides (EPS), gamma-amino butyric acid, proteolytic, lipolytic, autolytic, and amylolytic activity, resistance to acid conditions as well as biogenic amine production and susceptibility to antibiotics. Most of the examined strains presented high proteolytic and autolytic activity. Low acidifying ability was observed for all isolates, except for L. plantarum (M19) which reduced pH to 4.6 after 12 h. The highest proteolytic activity (30-mm clear halo) was observed for L. brevis (M4). Lipolytic activity was never observed and most of the isolates did not produce biogenic amines. The highest percentage of antibiotic resistance (87%) was recorded for kanamycin. All isolates were sensitive to chloramphenicol except L. brevis (M11). EPS production was detected in all strains, most strains (90%) produced mucoid EPS and 10% secreted EPS with a “ropy” character. Acid resistance showed all isolates were able to grow at pH 3.0 and 4.0. L. brevis (M4) presented the best technological characteristics and is proposed for inclusion as co-culture in the production of Motal Cheese.