Resumen

RAMOS-IZQUIERDO, B et al. Isolation, identification and characterisation of lactic acid bacteria for the manufacture of tropical cream cheese. Universidad y ciencia [online]. 2009, vol.25, n.2, pp.159-171. ISSN 0186-2979.

The purpose of this study was the isolation, identification and characterisation of 20 strains of lactic acid bacteria (LAB) from a "tropical cream cheese" traditionally prepared with non-pasteurised milk. The 20 strains of LAB were grown in de-creamed milk, and each one was evaluated with respect to its acidifying capacity (pH) at four incubation times (6, 24, 48 and 72 h) and three incubation temperatures (30, 37 and 42 °C). Based on the lowest pH, 6 strains were selected to prepare a "tropical type cream cheese" with pasteurised milk. The strains were characterised by means of biochemical tests (fermentation of carbohydrates and ammonia production from arginine) and 16S rDNA sequencing methods. Five species of L. fermentum and one species of L. pentosus were identified. Each strain presented significant differences (p < 0.05) with respect to fermentation temperatures and incubation times. The lowest pH values were recorded at temperatures of 37 °C and 42 °C after 72 h of incubation. Lactic acid, acetic acid, propionic acid and butyric acid were evaluated in the fermented milk for each strain, and there were no significant differences in the production levels of these metabolites (p > 0.05). Total counts were recorded for non-lactic flora, LAB, total coliforms, Escherichia coli, yeast and moulds in the cream cheese made with pasteurised milk. The artisanal cream cheese was used as a reference. The lowest counts of microorganisms were found in the cheese prepared with pasteurized milk (p < 0.05). The number of lactic bacteria was similar in both types of cheese (p > 0.05).

Palabras llave : Lactic acid bacteria; 16S rDNA; cheese; starter cultures.

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