Isolation and identification of yeasts and filamentous fungi from yoghurts in Brazil

Brazilian Journal of Microbiology

Silvia Regina Moreira²  Rosane Freitas Schwan²  Eliana Pinheiro De Carvalho¹  Alan E. Wheals² 

[1] ,Universidade Federal de Lavras Departamento de Biologia

关键词: yeasts;    filamentous fungi;    yoghurts;    deterioration;    leveduras;    fungos filamentosos;    iogurtes;    deterioração;   

DOI  :  10.1590/S1517-83822001000200009

来源: SciELO

【 摘 要 】

Seventy-two cartons of yoghurt were sampled three times at monthly intervals from four different local manufacturers. Total counts were close to 6 x 10(7) cells g-1 of yoghurt. Yeast counts varied from 1 to 2,700 g-1. There was no evidence of systematic contamination at source but this longitudinal study revealed that ad hoc contamination and improper storage led to the higher yeast counts. Contamination was generally higher in the hotter months but was lower overall than reported from other countries. A total of 577 yeast isolates were identified belonging to ten species. The most abundant yeasts were, in order, Debaryomyces hansenii, Saccharomyces cerevisiae, Mrakia frigida, Hansenula spp., Candida parapsilosis, Debaryomyces castellii and Candida maltosa. The psychrophilic yeast Mrakia frigida is reported for the first time in yoghurts. Low level contamination with Monilia and Penicillium species was found in a few samples. Growth tests suggested that ability to ferment sucrose, growth at 5° C and in the presence of 300 µg g-1 sorbate preservative, were the three most significant physiological properties to account for these yeasts in yoghurts. The data also suggest that warmer weather and inadequate refrigeration are the principal causes of higher levels of contamination, increased diversity and change in microbial flora.

【 授权许可】

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