A microbial assessment scheme for the cooked chilled food production process

C

Growth and inactivation of Salmonella enterica and Listeria monocytogenes in broth and validation in ground pork meat during simulated home storage abusive temperature and home pan-frying

Ground pork meat with natural microbiota and inoculated with low initial densities (1-10 or 10-100 CFU/g) of Salmonella enter/ca or Listeria monocytogenes was stored under abusive temperature at 10 degrees C and thermally treated by a simulated home pan-frying procedure. The growth and inactivation characteristics were also evaluated in broth. In ground pork meat, the population of S. enter/ca increased by less than one log after 12 days of storage at 10 degrees C, whereas L. monocytogenes increased by 2.3 to 2.8 log units. No unusual intrinsic heat resistance of the pathogens was noted when tested in broth at 60 degrees C although shoulders were observed on the inactivation curves of L. monocytogenes. After growth of S. enter/ca and L. monocytogenes at 10 degrees C for 5 days to levels of 1.95 log CFU/g and 3.10 log CFU/g, respectively, in ground pork meat, their inactivation in the burger subjected to a simulated home pan-frying was studied. After thermal treatment S. enter/ca was undetectable but L. monocytogenes was recovered in three out of six of the 25 g burger samples. Overall, the present study shows that data on growth and inactivation of broths are indicative but may underestimate as well as overestimate behavior of pathogens and thus need confirmation in food matrix conditions to assess food safety in reasonably foreseen abusive conditions of storage and usual home pan-frying of meat burgers in Belgium

Evaluation of Three Swabbing Devices for Detection of Listeria monocytogenes on Different Types of Food Contact Surfaces

Listeria monocytogenes can adhere to different types of food contact surfaces within a food processing environment. Therefore, environmental sampling devices should be capable of detecting unacceptable contamination. In this study, a sponge-stick, foam spatula and an environmental swab were evaluated on their ability to detect low concentrations of L. monocytogenes on different types of food contact surfaces. A cocktail of four L. monocytogenes serotypes was inoculated with a concentration of 100 CFU/250 cm2 onto stainless steel (SS), high density polyethylene (HDPE) and rubber surfaces in a 250 cm2 area. Immediately after inoculation and after 1 h exposure, the surfaces were swabbed with the different swabbing devices. The results of the study show only minor differences in the ability of the swabbing devices to detect L. monocytogenes. All devices were capable to detect the contamination immediately after inoculation. However, when the surfaces were allowed to air-dry for 1 h, L. monocytogenes was undetected in 11.1% of the samples (n = 27) with the sponge stick, in 7.4% of the samples (n = 27) with the foam spatula and in 3.7% of the samples (n = 27) with the environmental swab, especially on SS surfaces. The detection ability of the different devices for L. monocytogenes can be concluded to be rather high on different types of food contact surfaces