Disinfectant efficacy on foodborne spoilage yeast strains

Yeast strains are usually known for their beneficial role in the production of bread and fermented foods. Abundant growth of unwanted yeast strains during production can, however, lead to defects in the final products and problems with process hygiene when failures occur in the decontamination procedure. A low pH or a high sugar or salt content favours the growth of yeast strains. In many cases the risk caused by a growth of spoilage yeast strains in products has been underestimated because many of these yeast strains are not known to be opportunistic pathogens. The yeast strains also readily form biofilms on process surfaces at both low and elevated temperatures. The aim of this study was to assess the efficacy of various types of commonly used disinfectants against yeast strains isolated from dairy and bakery, fermented functional food, praline, confiture and sugar processes by means of both suspension and carrier tests. According to both suspension and biofilm tests, alcohol-based disinfectants are most effective in decontaminating the yeast strains isolated. Furthermore, the results showed that the tenside-based and peroxide-based disinfectants were efficient against suspended yeast cells. In the biofilm-carrier test the chlorine-based foam cleaner was also effective. The disinfectants containing chlorine and persulphate were ineffective in destroying yeast cells both in suspensions and in biofilm formations.