The occurrence of spoilage yeasts in cream-filled bakery products

BACKGROUND: Filling creams can provide an adequate substrate for spoilage yeasts because some yeasts can tolerate the high osmotic stress in these products. To discover the source of spoilage of a cream-filled baked product, end products, raw materials, indoor air and work surfaces were subjected to microbiological and molecular analyses. The efficacy of disinfectants against spoilage yeasts was also assessed. RESULTS: The analyses on end products revealed the presence of the closest relatives to Zygosaccharomyces bailii with counts ranging from 1.40 to 4.72 log cfu g−1. No spoilage yeasts were found in the indoor air and work surfaces. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis, carried out directly on filling creams collected fromunopened cans, showed the presence of bands ascribed to the closest relatives to Z. bailii sensu lato, although with counts<1 log cfug−1. Susceptibility testing of yeast isolates to disinfectants showed a significantly lower effect of 10% alkyl dimethyl benzyl ammonium chloride. Different responses of isolates to the tested disinfectants were seen. CONCLUSION: To guarantee the quality of end products, reliable and sensitive methods must be used. Moreover, hygiene and the application of good manufacturing practices represent the most efficient way for the prevention and minimization of cross-contamination.