As a means of ensuring the consistent taste and quality of their products, food companies monitor yeast and mould levels to make sure that they fall within regulatory and factory limits prior to leaving the plant.
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 or damaging consumers perceptions of the brand.
DuPont Qualicon says its new Bax system for yeast and mould uses a DNA-based technology called polymerase chain reaction (PCR) provides same day yeast and mould results for samples containing 500cfu/g (colony forming units per gram) using a direct method. The test can yield results in just two days for samples with 50-500cfu/g using an enrichment method.
"This is a considerable time saving compared to current culture techniques, which can take five to seven days to obtain a result," the company stated.
The yeast and mould screening procedures currently used by processors are culture-based, taking up to at least five days to complete. The results are often difficult to read accurately.
Using the Bax enrichment method, a homogenised sample is enriched for 44 hours in the equipment's disrupter tube. For both the direct method and the enrichment method, a DNA stabiliser is added and the tubes are agitated for 15 minutes prior to lysis and processing in the Bax system cycler.
After four hours, the system displays whether the test show above threshold contamination or not. 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, DuPont Qualicon stated.