Application of the direct epifluorescent filter technique as a rapid method in microbiological quality assurance in the meat industry

The direct epifluorescent filter technique (DEFT) and the standard plate count (SPC) were compared in the examination of raw and heat-treated meat products. The most promising results were obtained with raw ground beef, where good agreement was found between DEFT and the SPC. These products had bacterial counts of 10⁵/g and above; the correlation coefficient was 0.79. For heat-treated meat prooducts, good agreement between DEFT and SPC was found for products with high counts at the end of shelf life (10⁸/g), whereas very poor agreement was found in products with low counts. Nevertheless, useful information with DEFT was also found in these cases, since it was possible to estimate approximately the number of bacteria present before heat treatment. The study clearly showed that DEFT could not distinguish between live and dead cells, and also that this was not a prerequisite for using DEFT. It was concluded that DEFT could be used with advantage in a meat quality assurance programme for ground beef to check that a microbiological specification of 10⁶/g was adhered to. However, automatic counting could not be used at this level. This limits the capacity to 20 samples per person per day. It is hoped that further development of the DEFT system will overcome this problem.