Evaluation of a novel dry sheet culture method (Sanita-kunR) for rapid enumeration of yeasts and molds in foods

• We developed novel dry sheet culture medium for rapid enumeration of viable fungi.
• The originally synthesized tetrazolium salt was incorporated in this medium.
• New medium was evaluated for inclusivity according to ISO 16140.
• This medium was compared with ISO 21527-1 and other 2 dry culture methods.
• This new medium has a possibility to be a useful alternative for rapid enumeration.

Sanita-kunR Yeasts and Molds (SkYM), a novel dry sheet culture method for rapid enumeration of fungi, has been developed. This re-hydrated plate consists of a unique adhesive sheet, non-woven fabric coated with nutrients, antibiotic, water absorption polymer and uniquely synthesized 2-(2-methoxyphenyl)-3-(4-nitrophenyl)-5-phenyl-tetrazolium chloride for rapid enumeration of yeasts and molds. When SkYM was assessed using 37 microbes including 33 fungal strains, 29 fungal strains (87.9%) were formed red colored colonies within 48 h whereas all yeasts and molds tested formed colonies within 72 h. All tested bacteria failed to grow. The SkYM method, with both 48 and 72 h of incubation, was compared with Dichloran Rose-Bengal Chloramphenicol Agar (DRBC; 5 days) according to ISO 21527-1, and with 3 M Petrifilm YM (PYM; 5 days) and Nissui Compact Dry YM (CDYM; 5 days) commercially available dry culture methods using 100 naturally contaminated foods. The linear correlation coefficients of SkYM (48 h) with DRBC, PYM and CDYM were 0.921, 0.929 and 0.947, respectively, whereas the linear correlation coefficients between SkYM (72 h) and DRBC, SkYM (72 h) and PYM, SkYM (72 h) and CDYM were 0.948, 0.877 and 0.911, respectively. These results demonstrated that SkYM was a useful alternative for rapid enumeration of yeasts and molds in foods.