Free access
Issue
Lait
Volume 82, Number 5, September-October 2002
Page(s) 579 - 587
DOI http://dx.doi.org/10.1051/lait:2002034


Lait 82 (2002) 579-587
DOI: 10.1051/lait:2002034

Ibores goat's milk cheese: Microbiological and physicochemical changes throughout ripening

Matilde Masa, Rafael Tablab, Javier Moricheb, Isidro Roaa, José Gonzaleza, José Emilio Rebollob and Pilar Cáceresc

a  Instituto Tecnológico Agroalimentario, Junta de Extremadura. Aptdo. 20107, Badajoz 06071, Spain
b  Departamento de Bioquímica, Biología Molecular y Genética, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain
c  Departamento de Microbiología, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain

Abstract
The microflora of Ibores cheese made with raw goat's milk without any starter addition was studied throughout the ripening period. The microbial counts for total lactic acid bacteria, presumptive lactococci and presumptive lactobacilli attained maxima of 9-10 log units with little or no variation throughout ripening. Leuconostocs and enterococci levels were 2-3 log units lower, also with little variation. Coliforms and staphylococci declined steadily from relatively high initial counts, the coliforms to low levels and the staphylococci disappearing completely. Moulds and yeasts were at low levels throughout ripening. Among the identified isolates, lactococci formed the prevalent group throughout ripening, followed by leuconostocs and enterococci at similar levels to each other, and then lactobacilli at low levels. The prevailing species and subspecies were Lactococcus lactis ssp. lactis, Leuconostoc mesenteroides ssp. dextranicum, Ln. mesenteroides ssp. mesenteroides, Weissella paramesenteroides, Enterococcus faecium, E. faecalis, Lactobacillus casei and Lb. plantarum. Small numbers of other species from each of the genera were also identified. The changes in certain physicochemical parameters during ripening were determined. By 60 days, the values of the pH, total solid content, and NaCl content were 5.18, 58.9% and 2.5%, respectively. The correlation of some of the physicochemical parameters with the log counts of the microbial groups was also established.

Résumé
Fromage des Ibores : changements microbiologiques et physico-chimiques pendant l'affinage. La microflore de fromages de type Ibores, faits avec du lait cru de chèvre, sans addition de levain, a été suivie pendant l'affinage. Les concentrations de bactéries lactiques totales, de lactocoques présumés et de lactobacilles présumés atteignaient un maximum de 9 à 10 log ufc $\cdot$g -1, sans changement notable pendant l'affinage. Pendant la même période, les concentrations de leuconostocs et d'entérocoques étaient de 2 à 3 log plus faibles. Les populations de coliformes et de staphylocoques diminuaient régulièrement à partir de valeurs relativement élevées. Les coliformes ne disparaissaient pas totalement, contrairement aux staphylocoques. Les niveaux de moisissures et de levures étaient bas durant tout l'affinage. Parmi les isolats identifiés, les lactocoques constituaient le groupe dominant durant l'affinage, suivi des leuconostocs et des entérocoques (à des niveaux similaires) alors que les lactobacilles étaient rares. Les espèces et sous-espèces prédominantes étaient : Lactococcus lactis ssp. lactis, Leuconostoc mesenteroides ssp. dextranicum, Ln. mesenteroides ssp. mesenteroides, Weissella paramesenteroides, Enterococcus faecium, E. faecalis, Lactobacillus casei et Lb. plantarum. De rares isolats appartenant à d'autres espèces ont également été identifiés, pour chaque genre. Les changements de quelques paramètres physico-chimiques ont également été étudiés pendant l'affinage. Au bout de 60 jours les valeurs de pH, extrait sec et NaCl ont été de 5,18 ; 58,9 % et 2,5 % respectivement. De même, ont été établies des corrélations entre paramètres physico-chimiques et niveaux de populations des groupes microbiens.


Key words: Goat's milk cheese / ripening / lactic acid bacteria / identification

Mots clés : Goat's milk cheese / ripening / lactic acid bacteria / identification

Correspondence and reprints: Pilar Cáceres Tel.: 34 924289363; fax: 34 924271304;
    e-mail: pcaceres@unex.es

© INRA, EDP Sciences 2002

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