Analysis of cheese microflora | Sieru mikrofloras analīze
2010
Mikelsone, A., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology | Ciprovica, I., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Food Technology
Cheese microflora consists of starter, secondary and advetious microorganisms. Adventious microflora mostly is heterofermentative lactobacilli that originate from raw milk and factory environment. This flora opposite to starter cultures increase during ripening reaching 108 cfu gE-1, and contribute to the formation of typical desirable or atypical flavour and texture of product. The aim of the paper was to establish diversity and changes in dynamic of Lactobacillus ssp. during ripening of Krievijas cheese. Three different Krievijas cheeses were chosen for further analysis. Strain identification and counting of colony forming units were made for unripened sample right away after salting, then after 15, 30, 45, and 60 days samples ripened at 6 deg C and 12 deg C. Serial dilutions of each cheese sample (1:10 000, 1:100 000, and 1 000 000) in saline were made. Lactobacillus was cultivated using MRS media. Strain identification was performed by the API 50 CHL system (BioMerieux, Marey l'Etoile, France). Analyses were accomplished for unripened sample then after 15, 30, 45 and 60 days of ripening. Isolates were grouped by gram reaction by the 3% KOH method and catalase reaction by H2O2 method. Obtained results shown that all isolated Lactobacillus were Gram-positive, but catalase negative. Diversity of Lactobacillus indicated prevalence of Lactobacillus curvatus in Krievijas cheese. Moreover Lactobacillus plantarum 1, L.delbrueckii ssp. lactis 1, L. acidophilus 3, Leuconostoc lactis were isolated from Krievijas cheese samples. Lactobacillus plantarum 1 was isolated only from samples ripened at 12 deg C. Concentration of colony forming units after 60 days of ripening is higher in cheese ripened at 6 deg C.
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