Abstract
The enzymatic activities of 24 lactic acid bacteria strains have been studied. Lactobacilli strains exhibited the highest β-galactosidase and aminopeptidase activities. Acid phosphatase activity was high in lactobacilli and lactococci strains. Esterase activity was observed for leuconostoc and lactobacilli strains. The hydrophobicity test and the biogenic amines detection were also tested in some strains selected for their use as autochthonous starters in cheese manufacture. In general, all strains showed degrees of hydrophobicity greater than 70%, and were poor former of histamine and cadaverine and medium putrescine former. Tyramine production was medium in three strains and low in two strains of Lactococcus. Key words: Autochthonous starters, cheese, lactic acid bacteria, biogenic amines, enzymatic activity.
Highlights
Lactic acid bacteria (LAB) with interesting technological and probiotic properties are used as starters in the manufacture of fermented dairy products, such as milk drinks and yoghourts, and their use in cheese production is a common practice nowadays (Mäkeläinen et al, 2009)
Twenty-four strains were chosen on the basis of their antimicrobial activity against four Gram-positive reference strains from 420 strains isolated from Genestoso cheese, an artisanal Spanish raw cow’s milk cheese, to study their technological aptitude (González et al, 2007; 2010)
Lactobacilli and one strain of leuconostoc showed high βgalactosidase activity (> 40 nmol substrate hydrolysed). These results agree with those obtained by Mathara et al (2004) and Dewan and Tamang (2007), who reported that the β-galactosidase is the main enzyme by which homofermentative lactobacilli transform lactose into lactic acid. β-galactosidase contributes to the acidification of dairy products, reduces the intolerance to lactose found in certain human populations and can stimulate the growth and colonization of bifidobacteria with a probiotic effect in the human intestine (Zárate and López-Leiva, 1990)
Summary
Lactic acid bacteria (LAB) with interesting technological and probiotic properties are used as starters in the manufacture of fermented dairy products, such as milk drinks and yoghourts, and their use in cheese production is a common practice nowadays (Mäkeläinen et al, 2009). The cheese constitutes an adequate habitat for the probiotic bacteria in respect to the other fermented products, contributing to their survival in the human intestinal tract (Bergamini et al, 2009). LAB with decarboxylase activity of amino acids could produce biogenic amines (BA) in fermented foods, as is the cheese. Several authors have reported the presence of putrescine, cadaverine, histamine and tyramine in products in which LAB grow (Arena and Manca de Nadra, 2001; Martuscelli et al, 2005). Tyramine and histamine are the main biogenic amines in cheese (Burdychova and Komprda, 2007)
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