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Lec 1 food microbiology *Food microbiology : is the study of the microorganisms that inhabit, create, or contaminate food, including the study of microorganisms causing food spoilage . Contamination of food : The internal tissues of healthy plants (fruits and vegetables) and animals (meat) are essentially sterile. Yet raw and processed (except sterile) foods contain different types of molds, yeasts, bacteria, and viruses. Microorganisms get into foods from both natural (including internal) sources and from external sources to which a food comes into contact from the time of production until the time of consumption. Natural sources for contamination of foods of plant origin include the surfaces of fruits, vegetables, and grains, and the pores in some tubers (e.g., radish and onion). Natural sources for foods of animal origin include skin, hair, feathers, gastrointestinal tract, urinogenital tract, respiratory tract, and milk ducts (teat canal) in udders of milk animals The sources food contamination that can get into food and methods to reduce the levels of microorganisms are briefly: *A-Plants (Fruits and Vegetables): Fruits and vegetables harbor microorganisms on the surface; their type and level vary with soil condition, type of fertilizers and water used, and air quality. Molds, yeasts, lactic acid bacteria, and bacteria from genera Pseudomonas, Alcaligenes, Micrococcus, Erwinia, Bacillus, Clostridium, and Enterobacter. *levels of microorganisms Proper methods used to reduce of microorganisms: 1-during growing (such as use of treated sewage or other types of fertilizers), 2-damage reduction during harvesting, 3-quick washing with good quality water to remove soil and dirt, 4-and storage at low temperature before and after processing can be used to reduce microbial load in foods of plant origin. 1 Lec 1 food microbiology *B- Animals, Birds, Fish, and Shellfish: Food animals and birds normally carry many types of indigenous microorganisms in the digestive, respiratory, and urinogenital tracts, the teat canal in the udder, as well as in the skin, hooves, hair, and feathers Many, as carriers, can harbor pathogens such as Salmonella serovars pathogenic Escherichia coli, Campylobacter jejuni, Yersinia enterocolitica. Prevention of food contamination from these sources needs the use of effective husbandry of live animals and birds, which includes : 1-good housing and supply of uncontaminated feed and water. 2-Also, testing animals and birds for pathogens . 3-and culling the carriers are important in reducing the incidence of pathogenic microorganisms in foods. *C. Air: dry air with low dust content and higher temperature has a low microbial level. Spores of Bacillus spp., Clostridium spp., and molds, and cells of some Gram positive bacteria (e.g., Micrococcus spp. and Sarcina spp.), as well as yeasts, can be predominantly present in air. If the surroundings contain a source of pathogens (e.g., animal and poultry farms or a sewage-treatment plant), different types of bacteria, including pathogens and viruses (including bacteriophages), can be transmitted via the air. *D. Soil : soil , especially the type used to grow agricultural produce and raise animals and birds, contains several varieties of microorganisms. Because microorganisms can multiply in soil, their numbers can be very high (billions/g). Many types of molds, yeasts, and bacterial genera (e.g., Enterobacter, Pseudomonas, Proteus, Micrococcus,Enterococcus, Bacillus, and Clostridium) can enter foods from the soil. Different types of parasites can also get in food from soil. Note : Removal of soil (and sediments) by washing and avoiding soil contamination can reduce microorganisms in foods from this source. 2 Lec 1 food microbiology E. Sewage Sewage, especially when used as fertilizer in crops, can contaminate food with microorganisms, the most significant of which are different enteropathogenic bacteria and viruses. This can be a major concern with organically grown food and many imported fruits and vegetables, in which untreated sewage and manure might be used as fertilizer. Note : To reduce incidence of microbial contamination of foods from sewage, it is better not to use sewage as fertilizer *F. Water Water is used to produce, process, and, under certain conditions, store foods. It is used for irrigation of crops, drinking by food animals and birds, raising fishery and marine products, washing foods, processing (pasteurization, canning, and cooling of heated foods) and storage of foods (e.g., fish on ice), washing and sanitation of equipment, Note :Many food processors use water, especially as an ingredient, that has a higher microbial quality than that of potable water. *G- Human : human carriers have been the source of pathogenic microorganisms in foods that later caused foodborne diseases, especially with ready to eat foods. Improperly cleaned hands, lack of aesthetic sense and personal hygiene, and dirty clothes and hair can be major sources of microbial contamination in foods pathogens such as Sta. aureus, Salmonella serovars, Shigella spp., pathogenic Esc. coli, and hepatitis A can be introduced into foods from human sources. Note :Proper training of personnel in personal hygiene, regular checking of health, and maintaining efficient sanitary and aesthetic standards are necessary to reduce contamination. H. Food Ingredients : Starch, sugar, and flour might have spores of thermophilic 3 Lec 1 food microbiology bacteria. Pathogens have been isolated from dried coconut, egg, and chocolate. Note :The ingredients should be produced under sanitary conditions and given antimicrobial treatments. In addition, setting up acceptable microbial specifications for the ingredients will be important in reducing microorganisms in food from this source. I. Equipment: A wide variety of equipment is used in harvesting, slaughtering, transporting, processing,and storing foods. Many types of microorganisms from air, raw foods, water,and personnel can get into the equipment and contaminate foods. Note :Proper cleaning and sanitation of equipment at prescribed intervals are important to reduce microbial levels in food. J. Miscellaneous Foods might be contaminated with microorganisms from several other sources, namely packaging and wrapping materials, containers, flies, , birds, , and rodents. Conclusion Microorganisms enter foods from both internal and external sources. Their levels and types depend on the care used during production, processing, and storage of foods. Recontaminations of heat-processed foods with pathogens have been associated with many foodborne disease outbreaks. Proper sanitation at every stage helps reduce the microbial level normally expected in a food. 4 Lec 1 food microbiology *Food safety : is a major focus of food microbiology. It scientific discipline describing handling, preparation, and storage of food in ways that prevent foodborne illness Pathogenic bacteria, fungi ,parasites viruses and toxins produced by microorganisms are all possible contaminants of food. number of routines that should be followed to avoid potentially severe health hazards. 1-food safety considerations include the origins of food including the practices relating to food labeling, food hygiene, food additives and pesticide residues, 2-as well as policies on biotechnology and food and guidelines for the management of governmental import and export inspection and certification systems for foods. 3-In considering market to consumer practices, the usual thought is that food ought to be safe in the market and the concern is safe delivery and preparation of the food for the consumer. 4-Food can transmit disease from person to person as well as serve as a growth medium for bacteria that can cause food poisoning. 5-Thorough preparation of food, including proper cooking, eliminates most bacteria and viruses. However, toxins produced by contaminants may not be liable to change to non-toxic forms by heating or cooking the inhibit pathogens. 6-Alternatively, purified bacteriocins such as nisin can be added directly to food products. 7-Finally, bacteriophages, viruses that only infect bacteria, can be used to kill bacterial pathogens. contaminated food due to other safety conditions. 5 Lec 1 food microbiology Probiotic bacteria, including those that produce bacteriocins, can kill pathogens 8- other physical and chemical used for killing the microorganisms such as freezing , radiation and chemical materials . 6