Survival of Salmonella spp. in low water activity chicken base paste and powder formulated at different salt levels

Dry flavor ingredients such as black pepper and hydrolyzed vegetable protein (HVP) have been frequently recalled from the supply chain due to contamination with Salmonella. These spices are commonly used in preparation of savory meat flavor bases. This study evaluated the effect of various salt levels on the survival of Salmonella spp. in chicken bases formulated with pepper and HVP, in either paste or powder form. The salt content (% w/w), a_w and pH for regular-salt, 45% reduced-salt and 90% reduced-salt paste formulations were 33.0, 0.686, 5.75; 18.2, 0.691, 5.85; and 3.5, 0.751, 5.96, respectively, and powder formulations were 34.0, 0.254, 6.15; 18.5, 0.290, 6.28; and 3.1, 0.301, 6.50, respectively. To mimic natural contamination, a dry sand inoculation technique was used to prepare the samples. A five serovar cocktail of Salmonella was used and the final inoculation level in the samples was 7.5 ± 0.2 log CFU/g. Inoculated paste samples were stored at 21 °C for up to 12 weeks, and up to 42 weeks for powder formulations. Salmonella counts did not increase in either treatment during storage. The effect of salt levels on Salmonella survival was insignificant. There was a 5.2 ± 0.4 log reduction in paste formulations by 3 week. However, low Salmonella counts (<1.0 log CFU/g) were detected in samples from 6 to 12 weeks. In powder formulations, minimal log reductions of 1.3 ± 0.1 were observed over 42 weeks. When preparing a food product that does not undergo a kill step, it is necessary to ensure the absence of Salmonella in the ingredients, as well as practicing strict adherence to good manufacturing practices including proper environmental monitoring and sanitation in food processing. Furthermore, adequate consumer cooking instructions are important to ensure proper Salmonella lethality during preparation of reconstituted dry products.