A centrifugation/quadrant plate technique for the simplified differential-bacteriological examination of adequately heat-processed foods

Abstract

Foods manufactured or prepared, stored and distributed with due care for microbiological safety are likely to contain very low numbers of potentially hazardous bacteria. A centrifugation/quadrant plate method is described that allows the estimation of levels of contamination between 0·4 and 100 cfu/g of Enterobacteriaceae, Staphylococcus aureus, Bacillus cereus and other toxinogenic Bacillus spp., Streptococcus pyogenes and Listeria monocytogenes. When preceded by an adequate repair procedure, the method is reliable, convenient, rapid and inexpensive.

AN ELECTRICAL TESTING METHOD FOR THE DETECTION OF LISTERIA SPECIES IN CONFECTIONERY PRODUCTS

“…There is a need in the food industry for rapid methods suitable for Listeria detection. Rapid Listeria methods have been developed using flow cytometry (Donnelly and Baigent 1986), pyrolysis mass spectrometry (Freeman et al 1991), polymerase chain reaction (Furrer et al 1991;Wernars et al 1991), rapid nucleic acid hybridization assay @linger et al 1988), centrifugation quadrant plate method (Mossel et al 1991), sludge centrifugation (Lausseger and Asperger 1989), enzyme assays [ELISA] (Durham et al 1989;Farber et al 1987;Mattingly et al 1988;Normng et al 1991), dried gel hybridization (Wang et al 1991) and a microcolony technique combined with an indirect immunofluorescent method (Sheridan et al 1992). However, many of these are not suitable for testing large numbers of samples as is often required in food laboratories.…”