A microbial survey of food service can openers, food and beverage can tops and cleaning methodology effectiveness

Abstract

A can opener and food/beverage can top survey was undertaken to identify potential microbiological hazards. Results indicated the potential for high levels of bacterial and fungal contamination. Characterization of microorganisms from 10 can openers indicated the most common contaminants as Klebsiella pneumoniae and a variety of Staphylococcus and spore-forming Bacillus species. In contrast to previous commercial food service surveys, no Escherichia coli or Salmonella species were found on the cans or can openers, however, low numbers of Bacillus cereus (22 of 25 cans) and Clostridium perfringens (15 of 25 cans) were identified. The effectiveness of various can-cleaning methods was evaluated using marker bacteria (Serratia marcescens) suspended in soil consisting of tryptone soya broth, ground beef or vacuum cleaner dust. In addition to rinsing under running water, two paper towel types and a paper napkin product were used for wiping, moist wiping and wiping after rinsing. The most effective cleaning method was rinsing and wiping combined (P < 0.0003), while wiping alone was not as effective as moist wiping (P = 0.038) or rinsing with water (P = 0.061). Food cans were more easily cleaned than beverage cans because of the tab area. Soil type influenced the degree of effectiveness of the cleaning methods, with mean log₁₀ reduction values for each type at 3.4 and 3.1 for food and beverage cans (tab area excluded), respectively. No significant difference was observed in the effectiveness of paper products (P = 0.433).