ABSTRACT
The ubiquitous nature of microbes renders their presence inevitable in the food-processing chain as well as in domestic kitchens. Their introduction into a sterile or well-disinfected environment and their establishment on an abiotic or biotic surface is termed contamination. The major contamination source in such environments derives from the incoming raw materials, which may be carriers of a large and diverse association of spoilage bacteria, such as pseudomonads, enterobacteria, lactic acid bacteria, enterococci, yeasts, and molds. From a food safety aspect, these raw materials may also serve as vehicles of pathogenic microorganisms, including Listeria monocytogenes, Salmonella spp., Escherichia coli, Vibrio parahaemolyticus, Shigella, and Campylobacter. These microorganisms may be part of the indigenous microora of the food (of plant or animal origin), retrieved from the direct contact with the growth environment or introduced to the food during harvest and subsequent handling in the eld and/or during slaughter and further-processing and storage. Similarly, the working staff in a food-processing environment or the cook in a domestic kitchen may also assist in the introduction and spreading of undesirable
6.1 Routes and Vehicles of Bacterial Immigration in the Food Industry and the Domestic Environment ...................................................................................................... 89 6.1.1 Food Handlers ................................................................................................................... 91 6.1.2 Cleaning Sponges, Cloths, and Towels.............................................................................. 92 6.1.3 Kitchen Utensils and Storage Containers .......................................................................... 92 6.1.4 Other Vehicles of Cross-Contamination ........................................................................... 93
6.2 Factors Affecting Attachment of Pathogens on Food Contact Surfaces-Biolm Formation ..... 93 6.2.1 Type of Surface .................................................................................................................. 94 6.2.2 Microbial Strain................................................................................................................. 95 6.2.3 Temperature ....................................................................................................................... 96 6.2.4 Surface Conditioning ......................................................................................................... 97 6.2.5 Mixed-Species Biolm Formation .................................................................................... 97 6.2.6 Persistence, Survival, and Stress Hardening of Attached Populations ............................. 97
6.3 Stochastic Description of Bacterial Transfer ................................................................................. 99 6.3.1 Transfer between Abiotic Surfaces and Foods of Plant Origin ....................................... 100 6.3.2 Transfer between Abiotic Surfaces and Foods of Animal Origin ...................................101 6.3.3 Modeling Bacterial Transfer............................................................................................ 103
6.4 Concluding Remarks .................................................................................................................... 105 References .............................................................................................................................................. 105
microbes, especially of pathogenic nature. In particular, food handlers may be potential disease vectors without experiencing any obvious symptoms. For instance, Staphylococcus aureus is commonly encountered on human skin and skin wounds, nose, or throat, and it can be easily transferred to foods or food-related surfaces. Other sources of undesirable contamination in the food industry or a kitchen environment include the water used for washing of the equipment, utensils, or the pets and pests that have access to a food preparation site, which may excrete a variety of food-poisoning microorganisms. For these reasons, it is of high importance that the hygienic level of the incoming raw materials as well as that of the food handlers should be strictly maintained and regularly validated, while all the food-related environments should also be protected from animals and pests.
