sources of contamination of food.ppt, slideshare

Source of contamination of food
Food microbiology

1. VIVeKANANDHA artS and science college for women Veerachipalayam-637 303,Sankagiri,Salem Dt, Tamilnadu,India . Affiliated to Periyar University Salem ; recognised under section 2(f)&12(b) of the UGC act,1956 DEPARTMENT OF MICROBIOLOGY SUBJECT : FOOD MICROBIOLOGY TITLE : SOURCE OF CONTAMINATION OF FOOD SUBJECT INCHARGE : Dr.DINESH KUMAR Assistant professor Department of Microbiology VIAAS , Sankagiri . SUBMITTED BY : SWATHI NATRAJAN III B.sc Microbiology Department of Microbiology
VIAAS , Sankagiri .

2. CONTENTS Introduction From green plants and fruits From animals From sewage From soil From water From air During handling and processing

3. INTRODUCTION Growing plants carry a typical flora of microorganisms on their surface and may become contaminated from outside sources.Animals likewise have a typical surface flora plus an intestinal one ,give off organisms in excretions and secretion and also become contaminated from outside sources. Plants and animals with parasitic disease of course,carry the pathogen causing the diseases. The inner, healthy tissues of plants and animals, however have been reported to contain few living microorganisms or none. Major contaminations of food sources like, water ,air , dust, equipment, sewage, insects, rodents and employees also. Contamination of raw materials can occurs from soil, sewage, animals, external surface and organs of meat animals.

4. Cycle of contamination of food

5. FROM GREEN PLANTS & FRuIts The natural surface flora of plants varies with the plant.but usually includes species of Ps eudomonas , Alcaligenes,Flavobacterium and Micrococcus, Coliforms & lactic acid bacteria. Lactic acid bacteria include lactobacillus brevis and plantorum , Leuconostoc mesenteroides and lextranium , Streptococcus faecium & faecalis . Bacillus species, yeasts and molds also may be present.The number of bacteria will depend on the plant & it’s environment and may range from a few hundred or thousand per square centimetre of surface to millions. The surface of wall washed tomoto , for example; may show 400 to 700 microorganisms per square centimetre .

6. Outer tissue of unwashed cabbage might contain 1 million to 2 million microorganisms per gram,but washed and trimmed cabbage might contain 200,000 to 500,000 . Healthy tomatoes have been shown to contain Pseudomonas, Coliforms,Achromobacter , Micrococcus and Corynebacterium have been found in healthy root and tuber vegetables.

7. From animals Sources of microorganisms from animals include the surface flora ,the flora of the respiratory tract and the flora of gastrointestinal tract. However, hides,hooves and hair contain not only large numbers of microorganisms from soil,manure,feed and water but also important kinds of spoilage. The skin of many meat animals may contain Micrococcus, staphylococci and beta-hemolytic streptococci. Pig or beef carcasses (dead body animal ) may be contaminated with salomonellae . Because of further processing and handling, very few of these organisms result in human salmonellosis.

8. Many infections disease agents of animals can be transmitted to people via foods, but this represents only one of several transmission routes. Many of these diseases have been reduced or eliminated by improvement in animal husbandry. Agents of animal disease causing infections from foods would includes Brucella , Mycobacterium, Tuberculosis, Coxiella , Listeria,Campylobacter , beta-hemolytic streptococci, Salmonella, Enteropathogenic Escherichia coli, parasites and viruses.

9. From sewage When untreated domestic sewage is used to fertilize plant crops. The use of 'night soil’ as a fertilizer still persists in some parts of the world but , is rare in the US ( United States). Natural waters contaminated with sewage contribute their microorganisms to shellfish,fish and other seafood. Treated sewage going onto soil or into water also contributes microorganisms. Although it should contain smaller numbers and fewer pathogens than does raw sewage.

10. From soil The soil contains the greatest variety of microorganisms of any source of contamination. It’s not only numerous kinds of microorganisms but, also large total numbers are present in fertile soils, ready to contaminated the surfaces of plants growing on or in them and the surfaces of animals roaming over the land. Soil dust is whipped up by air currents and soil particles are carried by running water to get into or onto the foods. The soil is an important source of heat resistant spore forming bacteria.

11. No attempt will be made to list the microorganisms important in food microbiology that could come from the soil,but it can be started with certainty that nearly every important microorganisms can come from soil. Especially, various molds, yeasts and species of the bacterial genera Bacillus, Clostridium,Enterobacter , Escherichia, Micrococcus, Alcaligenes , Flavobacterium,Chromobacterium , Pseudomonas, Proteus, Streptococcus, Leuconostoc and Acetobacter as well as some of the higher bacteria such as the Actinomycetes and the iron bacteria. Modern methods of food handling usually involve washing the surfaces of foods and hence the removal of much of the soil from those surfaces and care is taken to avoid contamination by soil dust.

12. From water Natural waters contain not only their natural flora but,also microorganisms from soil and possibly from animals or sewage. Surface waters in streams or pools and stored waters in lakes and large ponds vary considerably in their microbial content, from many thousands per milliliter after a rain storm to the comparatively low numbers that result from self purification of quiet lakes and ponds or in running water. Ground waters from springs or wells have passed through layers of rock and the soil to a definite level.

13. The kinds of bacteria in natural waters are chiefly species of Pseudomonas, Chromobacterium , Proteus, Micrococcus, Bacillus, Streptococcus ( Enterococci), Enterobacter and Escherichia. Test for indicator bacteria can be confirmed and completed by methods described in American public health association (1985). E.coli which is considered more often of intestinal origin. Chlorination of drinking water is practised when there is any doubt about the sanitary quality of the water, the amount of available chlorine per million parts of water. Desirable chemical composition is affected by hardness and alkalinity as well as by the content of organic matter,iron , manganese and fluorine.

14. From air Contamination of foods from the air may be important for sanitary as well as economic reasons. Disease organisms, especially those causing respiratory infections,may be spread among employees by air or food product may become contaminated. Total numbers of microorganisms in a food may be increased from the air, especially if the air is being used for aeration of the product,as in growing bread yeast , although the numbers of organisms introduced by sedimentation from air usually are negligible. Spoilage organisms may come from air,as may those interfering with food fermentations. Mold spores from air may given trouble in cheese,meat , sweetened condensed milk ,sliced bread and bacon.

15. During handling & processing The contamination of foods from the natural sources just discussed may take place before the food is harvested or gathered or during handling and processing of the food. Additional contamination may come from equipment coming in contact with foods, from packaging materials and from personal. The processor attempts to clean and 'sanitize’ equipment to reduce such contamination and employ packaging materials that will minimize contamination. The term 'Sanitize’ is used here rather than 'sterilize’ because although an attempt is made to sterilize the equipment. i.e., free it of all living organisms, sterility is seldom attained.

16. Personal in food processing plants can contaminate foods during handling and processing. Various workers suggest that human beings shed from 10 3 to 10 4 viable organisms per minute. The numbers and types of organisms shed are closely related to the subjects working environment. Since the role of the food handler in food borne disease outbreaks has been clearly demonstrated, from a public health aspect this source of contamination has received considerable attention.

17. References Textbook of Food Microbiology , Virendra Kumar Pandey. https://images.app.goo.gl/5m76D5K46E82tcKZA . https://images.app.goo.gl/BTmZwH9V5xMQKpHr7

18. Thank you!