Methods for Recovering Microorganisms from Solid Surfaces Used in the Food Industry: A Review of the Literature

Abstract

Various types of surfaces are used today in the food industry, such as plastic, stainless steel, glass, and wood. These surfaces are subject to contamination by microorganisms responsible for the cross-contamination of food by contact with working surfaces. The HACCP-based processes are now widely used for the control of microbial hazards to prevent food safety issues. This preventive approach has resulted in the use of microbiological analyses of surfaces as one of the tools to control the hygiene of products. A method of recovering microorganisms from different solid surfaces is necessary as a means of health prevention. No regulation exists for surface microbial contamination, but food companies tend to establish technical specifications to add value to their products and limit contamination risks. The aim of this review is to present the most frequently used methods: swabbing, friction or scrubbing, printing, rinsing or immersion, sonication and scraping or grinding and describe their advantages and drawbacks. The choice of the recovery method has to be suitable for the type and size of the surface tested for microbiological analysis. Today, quick and cheap methods have to be standardized and especially easy to perform in the field.

Efficacy of a Sonicating Swab for Removal and Capture of Listeria monocytogenes in Biofilms on Stainless Steel

“…L. monocytogenes is commonly known to survive in biofilms in these environments, as a result of insufficient cleaning protocols compounded by the ability of the microorganism to resist chemical disinfection (5,7,13,31). In conjunction with the resilient structure of Listeria biofilms, the nature of the surface material (i.e., smooth or rigid, porous or nonporous) can determine the ability of the organism to remain attached to a surface (9,14,32). The location of bacterial biofilms and cell attachment can be directly responsible for the ability of the organism to evade detection.…”

“…monocytogenes is a microorganism that is continuously associated with foodborne illness outbreaks (14). It can be found in food such as ready-to-eat sandwiches, salads, and sprouts and in food processing environments, on equipment such as delicatessen slicers and in milk storage tanks (20,28).…”

“…Sonication is well established as a method to clean surfaces and aid in the removal of biofilms from many types of material surfaces (17)(18)(19). Sonication can be applied to remove adhered biofilms while maintaining cell viability, if employed properly (14,20,21). Biofilm-associated bacteria grown on polyvinyl chloride and stainless steel slides had higher recovery rates when placed in a sonication bath, in comparison with sampling with cotton swabs (21).…”

“…Swabbing is the standard method for microbiological sampling of surfaces, and cotton-tipped swabs are used most commonly for this purpose (10,14,15). Although cotton swabbing offers portability and ease of use, there are limitations, such as high user variability and low recovery, which render this approach unfavorable (8,15).…”

Knowledge, Attitude and Practice of Food Utensils Hygiene amongst Food Handlers in Kuala Pilah, Negeri Sembilan, Malaysia

“…Some bacteria survive on food utensils if cleaning and sanitizing are ineffective (Cosby et al 2008). Microbiological analysis of food utensils has been used to check hygiene of food utensils and practices of food handlers in food preparation (Ismail et al 2013). Contaminated food utensils should not be used for food preparation, especially for ready to eat food.…”