Vol. 3 núm. 2 - Sociedad Española de Microbiología

92nos que variaban según el tipo de queso. El contenido en termonucleasa se correlacionaba(positivamente) con los recuentos de enterococos y con el grado de maduración (sóloen queso Manchego). No se observó ningún tipo de relación entre los recuentos de coliformestotales y de enterococos.IntroductionManchego and Burgos cheeses are two of the most popular Spanish cheeses (15, 16).Both types are made total or partially from ewe's milk. Manchego is a hard cheese ripenedfor more than 60 d, whereas Burgos is an unripened soft cheese consumed whithin a shorttime after manufacture (48 h).Although a great deal of information on cheese is available and several papers onManchego and Burgos cheeses have been already published (8, 23, 27), there are veryfew works attempting to establish relationships between compositional and microbiologicalcharacteristics.In recent years, there is a trend to consider food microbiology in the context ofecology. According to Board (6), the concepts of ecology aid interpretation of dataderived from studies in food microbiology.Principal component analysis is one of the best ways of studying multivariatevariation. Application of this technique to research in ecology is useful and relativelyfrequent (17, 24) but publications using this method in food microbiology have not beenfound.Data on composition and microbiological quality (range, mean, etc.) have beenpreviously reported (10). The aim of this work was to examine the correlations betweentwo sets of variables, one representing the physico-chemical characteristics of Manchegoand Burgos cheeses, and the other representing counts of several microbial groups.Material and methodsCheesesDuring a year, 72 samples (36 of Manchego cheese and 36 of Burgos cheese) wereobtained at random from retail outlets in the city of León. Sampling was performedaccording to LC.M.S.F. (13). All samples were manufactured at the Castilla-León areaand their labels indicated «made with pasteurized ewe's milk».Physicochemical variablesFat content (7), moisture content and salt content (1), pH value (26) and wateractivity (20) were determined and used as data.Microbiological variablesThe following counts were performed: mesophiles and psychrotrophs (2), coliformsand yeasts and molds (14), enterococci (in Kanamycin Aesculin Azide broth —Oxoid—