A new rapid method for the quantification of yeasts and moulds in food samples is now available from Oxoid
The new Bax system yeast and mould PCR assay provides same day yeast and mould results for samples containing 500cfu/g (direct method), or in just two days for samples with 50-500cfu/g (enrichment method).
This is a considerable time saving compared to current culture techniques, which can take five to seven days to obtain a result.
Although yeasts and moulds do not normally cause human illness, high levels may cause food products to spoil prematurely.
This may cause the product to look, smell or taste bad, thus diminishing the appeal of the product and the brand.
It may even damage consumer perceptions of the retail outlet where the product was purchased.
In order to ensure consistent taste and quality of their products, food companies monitor yeast and mould levels to make sure that they fall within acceptable limits prior to leaving the factory.
Yeast and mould counts also help in determining the suitable shelf life of a product.
Current yeast and mould screening procedures are culture-based, requiring a laborious plating method.
This can take at least five days to complete and is often difficult to read accurately.
The new Bax System yeast and mould assay enables meaningful yeast and mould quantifications to be performed in just two days or less.
The Bax method is extremely easy to perform and requires little hands on time.
For the enrichment method, homogenised sample is enriched for 44 hours in the disrupter tube.
For both the direct method and the enrichment method (following incubation), DNA stabiliser is added and the tubes are agitated for 15 minutes prior to lysis and processing in the Bax system cycler.
After just four hours, the system displays positive (above threshold) or negative (below threshold) results.
The target threshold is set according to the action levels of each individual laboratory, validated against historical plate counts for specific food products.
The Bax System assay detects both filamentous (hyphae) and non-filamentous fungi (yeasts and spores), ensuring accurate results regardless of the stage in the life-cycle of the target organisms.
The system has been tested on a variety of foods, including cheese and flour products.
