Following a request from the European Commission, the Panel on Biological Hazards (BIOHAZ Panel) and the Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF Panel) were asked by the European Food Safety Authority (EFSA) to deliver a Scientific Opinion on an application dossier submitted by the U. S. Department of Agriculture (USDA) for the approval of lactic acid for uses to reduce microbial contamination of beef hides, carcasses, cuts and trimmings. More specifically, the approval was sought for treatments using lactic acid solution concentrations from 2 % to 5 % (wt/wt) at temperatures of up to 55 °C applied either by spraying or misting.
The Commission asked EFSA to issue a Scientific Opinion on the assessment of the safety and efficacy of lactic acid when used to reduce microbial surface contamination on beef hides, carcasses, cuts and trimmings. Specifically, the task was to consider the toxicological safety of the substance, its antimicrobial efficacy, the potential emergence of reduced microbial susceptibility to biocides and/or resistance to therapeutic antimicrobials linked to the use of the substance, and any risk related to the release of the slaughterhouse and/or processing plant effluents containing the substance into the environment. The assessment was based on the document “Guidelines on the submission of data for the evaluation of the safety and efficacy of substances for the removal of microbial surface contamination of foods of animal origin intended for human consumption” published by EFSA.
Concerning the human toxicological safety of the substance, it was concluded that the treatments, as described, would be of no safety concern provided that the substance used complies with the European Union specifications for food additives. This was based on the expected low level of exposure deriving from the use of lactic acid on carcasses, cuts and trimmings, and the fact that it is an endogenous substance.
A total of 25, of the 52 papers submitted by the applicant, were selected based on identified criteria and were used in the assessment of the efficacy of lactic acid as a decontaminating agent for beef hides, carcasses, cuts and trimmings. Since no studies were submitted for the evaluation of the lactic acid efficacy when its application was followed by water rinsing, this sequence of treatments was not assessed. Evaluation of the efficacy of lactic acid for decontamination of hides was also not performed since all relevant studies submitted evaluated 10 % lactic acid (not the requested maximum of 5 %) or the application method used in the studies was not requested for approval.
The studies described in the selected papers used a wide range of experimental designs and thus differed in relation to products, settings, method of application, lactic acid concentration, use of controls, microorganisms studied, time and temperature of storage, etc. All of these factors impacted on the efficacy both within and between studies. Given this wide range of application conditions, the evaluation did not attempt to differentiate effects due to different factors, such as lactic acid concentration and temperature of application, within the limits considered, which might influence its efficacy.
Studies on industrial scale and pilot scale which are representative of industrial scale with naturally contaminated products were considered as providing high strength of evidence. Pilot studies with naturally contaminated products and with inoculated pathogenic microorganisms and laboratory studies with naturally contaminated products were considered as providing medium strength of evidence. Laboratory studies with inoculated pathogenic microorganisms were considered as providing low strength of evidence. Based on studies classified by the Panel as of high strength of evidence, lactic acid reduced counts of naturally occurring Enterobacteriaceae on beef carcasses, cuts and trimmings to a variable degree. However, these reductions were usually significantly higher compared to untreated or water treated controls. According to studies classified as of high or medium strength of evidence, lactic acid reduced the prevalence of Salmonella and/or Shigatoxin-producing/Verotoxin-producing Escherichia coli (STEC/VTEC) on carcasses, beef cuts and trimmings to varying degrees depending on study design and contamination level. Based on studies classified as of medium strength of evidence, lactic acid was shown to reduce counts of inoculated pathogens (Salmonella and/or STEC/VTEC) on beef carcasses, cuts and trimmings to a variable degree. Usually reductions were higher on carcasses compared to meat cuts and trimmings.
Data to address the issue of the potential emergence of reduced susceptibility to biocides and/or resistance to therapeutic antimicrobials linked to the use of the substance were not provided. It was however concluded that the development of enzymatic resistance to therapeutic antimicrobials as a result of exposure to lactic acid is unlikely. Considering the extensive natural presence of lactic acid in fermented food, the possibility of mutational change resulting in the development of resistance to therapeutic antimicrobials is also unlikely to be a significant issue. There is some evidence that repeated exposure to lactic acid can select for reduced susceptibility to the substance. Under good hygienic practices (GHP), this possibility is not considered a significant issue.
This Scientific Opinion further points out that the concentration of lactic acid just before entering the wastewater treatment system is considered as negligible. For this reason, an environmental risk assessment was considered as not necessary.
It is recommended that, according to HACCP principles, during use, food business operators verify lactic acid concentration, temperature of application and other factors affecting its efficacy as a decontaminating agent. Because of the variability between various studies, it is also recommended that food business operators validate the antimicrobial efficacy under their specific processing conditions.