Survival assessment of Salmonella enterica in inoculated pork salami

Abstract

Pork salami is an embedded, cured and ripened product commonly consumed in Brazil, and the presence of Salmonella enterica has already been reported in this product. During its preparation, the microbiological safety depends on the meat quality, addition of ingredients with antimicrobial activity, hygiene during processing, pH and water activity (Aw) reduction during maturation. In Brazil, the maturation protocol has not been determined in food regulation; therefore, the objectives of this study were (a) to identify the fermentation and drying phases during salami maturation; (b) to test the survival of S. enterica during salami processing; and (c) to compare xylose lysine deoxycholate (XLD) and thin agar layer (TAL) agar for recovering Salmonella. The salami samples were prepared with a cocktail of S. enterica strains, fermented at 30°C and dried at 20°C with controlled relative humidity (RH). Periodic sampling for S. enterica quantification and Aw and pH analyses were performed during maturation, and curves were constructed. Fermentation occurred during the first 66 hours, and the pH decreased while the population of S. enterica increased over the first 21 hours. The drying step was able to reduce the bacterial population by approximately 5 log CFU after 875 hours, reaching an Aw of less than 0.78. However, elimination of S. enterica was not achieved. For Salmonella recovery, TAL agar was more efficient than XLD agar.

Effect of lactic acid stress on biofilm formation of Escherichia coli O26 at different temperatures

“…Low pH often occurred during food processing due to the use of acidic lotions and food additives as well as the presence of lactic acid in fermented food. For example, during the processing of fermented meat and dairy products, the pH fluctuates between 4.5 and 5.5 due to the production of lactic acid (Wang et al, 2012; Werlang et al, 2020). The strong capacity strain 126Z and medium capacity strain G13Z2 were selected to investigate BF under acid stress.…”

“…The widespread use of acidic preservatives and disinfectants provide a long‐term acid stress environment for foodborne pathogens (Galie, Garcia‐Gutierrez, Miguelez, Villar, & Lombo, 2018). In the process of fermented food, lactic acid is constantly produced and accumulated, which produces certain acid stress on microorganisms (Wang et al, 2012; Werlang, Vieira, Costa, & Cardoso, 2020). The effect of acid stress on the formation of biofilm of E. coli O157:H7 has been reported (Gould et al, 2009; Wang et al, 2020).…”