Combination of organic acids and low-dose gamma irradiation as antimicrobial treatment to inactivate Shiga toxin-producing Escherichia coli inoculated in beef trimmings: Lack of benefits in relation to single treatments

Abstract

The aim of this study was to assess the efficacy of lactic acid (LA), caprylic acid (CA), high-(HDI) and low-(LDI) dose gamma irradiation and LDI combined with LA or CA on the inactivation of a pool of Shiga toxin-producing Escherichia coli (STEC) strains inoculated on beef trimmings. The three most efficacious treatments were selected to study their effect on meat quality parameters and sensory attributes. The inoculum included five native STEC serogroups (O26, O103, O111, O145 and O157). The treatments applied were 0.5% LA, 0.04% CA, 0.5 kGy LDI, 2 kGy HDI, LDI+LA and LDI+CA. Beef trimmings were divided into two groups; one was inoculated with high (7 log CFU/g) and the other with low (1 log CFU/g) level of inoculum. Efficacy was assessed by estimating log reduction and reduction of stxand eae-positive samples after enrichment, respectively. Results showed that treatments with organic acids alone were not effective in reducing STEC populations. For high inoculum samples, the most effective treatment was HDI followed by LDI+LA and LDI alone or combined with CA. For low inoculum samples, the most effective treatment was HDI followed by LDI alone or combined with organic acids. Concerning meat quality parameters and sensory attributes, irradiation treatments (LDI and HDI) caused minimal changes, while LDI+LA modified them significantly compared with the control. Therefore, based on our results, no benefits were observed after combining organic acids with gamma irradiation.

Reduction of Shiga toxin-producing Escherichia coli in a beef abattoir

“…However, it was only possible to reduce less than 1 log of STEC. In Argentina, 2 log STEC/g reductions were obtained under experimental conditions in beef trimmings using high and low dose gamma irradiation (Cap et al, 2020). In addition, 5 log UFC STEC/g reductions were obtained in ground beef experimentally contaminated (Cap, 2020, personal communication).…”

Analysis of scenarios to reduce the probability of acquiring hemolytic uremic syndrome associated with beef consumption

“…In the present model, treatment with organic acids and hot water improved the quality of the meat produced in abattoirs, which would result in an improvement in public health. Among physical interventions, gamma irradiation is a well-known, safe and effective method for controlling microorganisms (Cap et al, 2020; Sommers et al, 2015; Xavier et al, 2014). In the scenario analysis of ground beef and hamburgers, it was demonstrated that the irradiation treatment would reduce 93.1 times the risk of HUS compared with the baseline scenario and considering the different population groups.…”

“…The Effect of irradiation on HUS probability from hamburger consumption was modeled using data reported by Cap et al (2020). These authors showed a net STEC >5 log CFU/g reduction (7 log CFU/ g before and < 2 CFU/g after the intervention) with the application of 0.23 kGy.…”

“…In general, the risk of HUS as a result of consuming ground beef from butcher shops without GMP or GHP is ∼Beta(0+1; 90−0+1) ∼Beta(30+1; 30−30+1) Cap et al (2020) STEC prevalence on trimmings after irradiation treatment (P (I) )…”

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

“…In selective media like MCA, only viable bacteria can form colonies. The difference between the two media counts were determined as injured cells (Cap et al., 2020a, b; Eccoña Sota et al., 2021; Espina et al., 2016). One the other hand, lethality was calculated as the difference between TSA counts of the HPP‐treated samples and TSA counts of control ones.…”