NeoFilm® for Yeast and Mold as an Alternative to Dilution Plating for the Enumeration of Yeast and Molds in Foods

Introduction: NeoFilm Yeast and Mold is a simple, effective device used for the enumeration of yeast and molds. A 1 ml sample homogenate is applied to a thin membrane pad, which is then incubated for 48 - 72 h at 25°C. The membrane pad is comprised of a nonwoven fabric that contains a layer of microbial nutrients deposited in film.

Purpose: To compare recovery levels of yeast and molds in NeoFilm Yeast and Mold, using either PBS or peptone water as a diluent, against the FDA/BAM reference method plating. Method performance was assessed for 5 food types: breaded chicken nuggets, dry pet food, orange juice concentrate, yogurt, and cake mix.

Methods: For each food, five separate sample homogenates were prepared with both diluents at three target inoculation levels: 10², 10³, and 10⁴. Each homogenate was either plated by the reference method or on NeoFilm. Data were statistically analyzed using a difference of means, P-value, and correlation coefficients.

Results: When using PBS as diluent, there were statistically significant differences only for orange juice concentrate at the 10³ level (P = 0.01), with reference yielding a higher count than NeoFilm, and cake mix at the 10³ level (P = 0.01), with NeoFilm yielding a higher count than reference. When using peptone water as diluent, there were statistically significant differences only for dry pet food at the 10² level (P = 10^-4), with reference yielding a higher count than NeoFilm, and cake mix at the 10² and 10³ levels (P = 0.01 and 0.001), with NeoFilm yielding higher counts than reference.

Significance: A high level of agreement was observed for the enumeration of yeast and molds as determined by NeoFilm Yeast and Mold and FDA/BAM reference methods.  Incubation times of 48 h for peptone water and 72 h for PBS are recommended.