High‐pressure processing treatment of beef burgers: Effect on Escherichia coli O157 inactivation evaluated by plate count and PMA‐qPCR

Abstract

Propidium monoazide coupled to real time PCR (PMA‐qPCR) is a novel methodology proposed for the quantification of viable bacteria in food after microbial inactivation treatments. The aim of this work was to assess the effectiveness of different pressure levels on the lethality of a pool of Escherichia coli O157 strains in beef burgers by plate count and PMA‐qPCR using uidA as target gene. Also, the effect on native microbiota counts, E. coli O157 counts, and physiochemical parameters of beef burgers during storage in refrigeration and frozen conditions were assessed. The treatment at 600 MPa for 5 min was the most lethal and was selected for the evaluation of bacteria behavior under storage conditions. Native microbiota and E. coli O157 were not recovered during refrigerated and frozen storage (4°C for 7 days and −18°C for 35 days). Cooking weight loss, pH, chromatic parameters, and texture were affected by HPP. Practical Application Practical Application: PMA‐qPCR can be used as an alternative to assess microbial inactivation by different high pressure processing (HPP) conditions (pressure level, holding time and temperature) more rapidly than conventional plate counts. In addition, it has the benefit of being able to quantify viable but nonculturable bacteria from contaminated beef burgers after HPP. Moreover, this novel technique generates less pathogenic residues, which minimizes workers' exposure to human biohazards.

Resistance to preservatives and the viable but non-culturable state formation of Asaia lannensis in flavored syrups

“…In the food industry, the detection of microorganisms is usually performed by traditional plate culture methods. However, some microorganisms that can tolerate exposure to salt, sugar, heat, and cold and environmental stress, such as starvation, high pressure, extreme temperature, hypoxia, and fungicides, could not Frontiers in Microbiology 07 frontiersin.org be isolated using this traditional method (Dong et al, 2020;De los Ángeles Rey et al, 2022). Some foods tested for microorganisms still spoiled after shelf storage with thermostable Lactobacillus (Liu et al, 2018) and Campylobacter (Wulsten et al, 2022).…”

Persistence of E. coli O157:H7 in Frozen Soils: Role of Freezing Temperature

“…There are few studies on the persistence of pathogenic microorganisms in frozen soils, while studies on frozen food were frequently reported, e.g., the persistence of EcO157 could be improved in frozen apple juice [18], and the survival of EcO157 and Salmonella was significantly lower in frozen stored raspberries [19]. Numerous studies have shown that EcO157 populations in frozen foods were slow to die off [20][21][22][23][24][25]. In addition, different frozen foods and the different handling of frozen foods can also affect EcO157 survival [26,27].…”