Clean-in-place (CIP) validation of oil-based cleaning and sanitization for Salmonella-contaminated tubing: Evaluation of Enterococcus faecium as a surrogate

Abstract

The safety of low-moisture foods is of continual concern due to the survival and cross-tolerance of certain bacterial pathogens under dry conditions. This study screened for Salmonella surrogates using a controlled bacterial desiccation system for testing against formulated antimicrobial oils. The effect of inoculum preparation on the heat resistance of Salmonella in peanut butter was also addressed. Thereafter, a tubing system was utilized to validate a dry cleaning and sanitation procedure at the temperature range of peanut butter processing. Tubes were contaminated by re-circulating peanut butter inoculated with a test organism to 108−9 CFU/g. The contaminated system was flushed with fresh canola oil under laminar flow for cleaning, followed by holding with acidified oil or water-in-oil (W/O) emulsion to sanitize. A linear relation (R2, 0.89) was observed between the oil-flush (cleaning) duration and surface cell removal, and the prevailing surface cleanliness dictated the efficacy of sanitization. System decontamination was achieved at 60 °C through a two-step oil flush (3.6 min) and acidified W/O emulsion treatment (30 min). The test organisms, S. Enteritidis phage type 30 and Enterococcus faecium NRRL B-2354, were reduced by this procedure to levels undetectable by enrichment of tubes (n = 9). The E. faecium showed less susceptibility than S. Enteritidis under all the conditions tested, suggesting that it may be used as a Salmonella surrogate to validate such a process in the food-processing environment. Adaptation of the proposed oil-based system would allow a shifted cleaning and sanitation paradigm precluding the necessity of traditional wet cleaning and application of flammable alcohol-based sanitizers.