The presence of yeasts in different types of cheese
1998
Welthagen, J.J. | Viljoen, B.C. (University of the Orange Free State, Bloemfontein (South Africa). Dept. of Food Science)
A total of 148 yeast strains were isolated from 67 different soft, semi-hard and hard cheeses obtained from different manufacturers. The different types of cheese were sampled for yeast counts after the ripening process and ready for marketing, and included both the inner part and the surfaces of the cheese. The yeast counts were performed on acidified YM agar. Counts on M17 (for the isolation of lactococci) and MRS (for the isolation of lactobacilli) agar plates were also included and analysed after incubation at 25 degees for 48 h. The yeast strains were identified using standard conventional identification methods. The predominant strains proved to be mainly Debaryomyces hansenii and Torulaspora delbrueckii, while strains of Sporobolomyces roseus, Cryptococcus laurentii, Saccharomyces cerevisiae, Candida glabrata, Candida castellii and Kluyveromyces lactis were also present in lower numbers. The results obtained showed yeasts were present in all the cheese samples examined, at numbers ranging from 900 to 104,000,000 cfu per g of cheese. Results from this study shown no association among yeasts strains and different cheese varieties. Debaryomyces hansenii was predominant in 20 of the different cheese varieties.
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