MILK AND MILK PRODUCTS- source, contamination, spoilage and prevention.

Milk and milk products ppt

1. VIVEKANANDHA ARTS AND SCIENCE COLLEGE FOR WOMEN VEERCHIPALYAM-637303,SANKAGIRI,SALEM Dt.,TAMILNADU,INDIA. AFFILIATED TO PERIYAR UNIVERSITY,SALEM;RECOGNISED UNDER SECTION 2(F)&12(B) OF THE UGC ACT 1956) SUBJECT INCHARGE; Dr.R.DINESHKUMAR, Assistant professor, Department of Microbiology, VIAAS,Sankagiri. DEPARTMENT OF MICROBIOLOGY SUBJECT : FOOD MICROBIOLOGY SUBMITTED BY; GOPIKA KRISHNAN, III B.SC.MICROBIOLOGY, DEPARTMENT OF MICROBIOLGY, VIAAS,Sankagiri. TITLE : MILK AND MILK PRODUCTS

2. OVERVIEW ; INTRODUCTON SOURCES OF CONTAMINATION OF MILK AND MILK PRODUCTS SPOILAGE OF MILK AND MILK PRODUCTS PREVENTION OF MILK AND MILK PRODUCTS YOGHURT CHEESE BUTTER

3. INTRODUCTION Milk products include milk,cream,butter,frozen,deserts, cheese, Fermented milk, condensed &dried milk products. The nutritional qualities of milk & milk products make the desirable foods for humans and young animals. Milk is a products of animal origin & its sanitary qualities are influenced by many factors in the course of its production, processing & delivery to consumer. Milk is brought from the farm to the for dairy processing.

4. SOURCES OF CONTAMINATION; 1. ON THE FARM :- During normal milking process, milk is subjected to contamination from udder of animal and adjacent areas. Bacteria are found in manure, soil and water contaminate udder of animal from where they enter into the milk . Undesirable bacteria from these sources include lactic streptococci, coliform bacteria, pychrotrophic gram-negative rods, and the thermoduries, those which survive pasteurization, e.g., micrococci, enterococci, bacilli, and brevibacteria. Other possible sources of contamination is hand and finger of milk or other dairy workers. Contamination also occurs from dairy utensils

5. 2. DURING TRANSPORT AND AT PROCESSING PLANT:- After milk is left in the farm, the possible contamination include the tanker truck , transfer pipes, sampling utensils , and the equipment at the market-milk plant or other processing plant. Pipelines, vats, tanks, pumps, valves, separator, clarifiers, homogenizers, cooler, strainers, stirrers, and filters are the possible sources of bacteria. Hands and arms of the employees are a possible sources of contamination and pathogens. The amount or level of contamination from each of these sources depends on cleaning and sanitizing methods.

6. SPOILAGE Milk is an excellent culture medium for many kinds microorganisms, being high in moisture, nearly neutral spoilage Ph, and rich in microbial foods. The genera found in cold–stored milk include, pseudomonas, Acinetobacter, Aerobacter Alcaligens, and Flavobacterium as well as some members of enterobacteriaceae. with extend storage of milk products at refrigerated temperatures, psychrophilic or psychotropic organisms are a cause of spoilage. Spoilage of milk usually is caused by psychrotrophs that contaminate the milk after pasteurization. Also involved are thermoduric psychrotrophs as well as heat-stable proteases produced before pasteurization.

7. SPOILAGE OF MILK AND MILK PRODUCTS GAS PRODUCTION PROTEOLYSIS ROPINESS CHANGES IN MILK FAT ALKALI PRODUCTION FLAVOR CHANGES COLOR CHANGES

8. SPOILAGE OF MILK This is contamination of milk with foreign substances and harmful bacteria that can cause illness to consumers. contamination And spoilage occur from before milking up to the time of consumption. contaminated milk is rejected by processors, dairy societies and consumers leading to loss of farmers income. Spoilt milk has various characteristics which include; Has clot or yellow brownish color. Clots on boiling. Bad smell. Appears watery.

9. CAUSES OF MILK SPOILAGE Various factors may contribute towards milk spoilage. These include; The cow; The cow may collect mud, straw, or dung from a poorly constructed or dirty shed which may contaminate milk cow disease also contaminate milk. The milker: If proper hygiene is not observed by the milker spoilage may occur. Environment : disease pathogen, flavours in feeds as well as straw, dung, and soil from the cow sheds environment may also contaminate milk. Environmental saprophytic micro-organisms : from teat canal, teat and udder skin, dust, manure, bedding material, feed, water, milking system, cooling tanks. Pathogenic microorganisms: from diseased cows- 80 per cent of inflamed quarter milk samples contain pathogenic bacteria.

10. PATHOGENIC MICROORGANISMS IN MILK Bacillus cereus. Listeria monocytogenes. Yersinia enterocolitica. Salmonella spp. Escherichia coli. Campylobacter jejuni.

11. SPOILAGE OF MILK PRODUCTS The microbial quality of milk product mainly depends upon: The type of milk and milk product used ( raw milk, condensed milk, dried milk, cream, butter, etc.) The products such as gelatin, nuts, fruits, sugar, chocolate, coloring agent, etc., Sanitary level of types of equipment, the efficiency of pasteurization, and hygienic level during production and packaging

12. PRESERVATION Milk is such a delicately flavored, easily changed food. Prevention of contamination or spoilage of milk is important in its preservation. Most of the milk products evolved for the purpose of improving keeping quality. To increase the keeping quality of milk one should have to decrease the no: of undesirable kinds of microorganisms. These undesirable organisms are:- lactic & coliforms :- they grow well in market milk. The psychrotrophs:- grow well at refrigeration temperature in stored milk. The thermoduries:- which survive pasteurization i.e., human pathogens.

13. PRESERVATION OF MILK AND MILK PRODUCTS FROM MICROBIAL SPOILAGE Reducing contamination Removal of microorganisms Use of heat Use of low temperature Drying Use of chemical preservatives

14. METHODS OF PRESERVATION Pasteurization Sterilization dehydration

15. FERMENTED FOOD PRODUCTS CHEESE YOGHURT BUTTER

16. FERMENTATION Microorganisms are the key building blocks of fermented foods and beverages The final products of fermentation is the result of chemical, physical & biological interactions between specific microbes & food. Bacteria, yeasts & molds are involved in food fermentation. sugar-alcohol +co2

17. FERMENTED MILK PRODUCTS : Butter milk : streptococcus sp., leuconostoc sp., Yoghurt : streptococcus thermophilus, lactobacillus bulgaricus. Cheese : streptococcus sp., lactococcus lactic.

18. BUTTER Butter may be defined as a concentrate which is obtained by churning cream, gathering the fat into a compact mass which includes a small portion of natural milk constituents with or without added salt and coloring matter and contained not less than 80% by weight of milk fat. PROPERTIES OF BUTTER: Generally butter has a pale yellow color, but varies from deep yellow to nearly white. Butter remains a firm solid when refrigerated . Its softens to a spreadable consistency at room temperature. Butter melts to thin liquid consistency at 32 to 35°c.

19. SPOILAGE OF BUTTER Butter is a milk product made by the separation of milk and subsequent churning of the cream. The main sources of microorganisms found in butter is cream which is starting material of butter. Therefore, the main spoilage is caused by pseudomonas, A eromonas, and alcaligenes. The primary spoilage organisms in butter are molds such as cladosporium, aspergillus , thamnidium. The pathogenic microorganisms like listeria monocytogenes, brucella, mycobacterium, salmonella tuphimurium.

20. CHEESE Cheese  is a dairy product that's made from milk solids. Many delicious foods are made even more delicious with melted  cheese , including pizza and nachos. Cheese is a food made from milk. Making cheese is a good way to preserve fresh milk, which quickly spoils. Like milk, cheese contains many nutrients, including protein, fat, calcium, phosphorus, and vitamins. Hundreds of different cheeses are produced and eaten all over the world.

21. SPOILAGE OF CHEESE Cheese is a fermented milk product that is made by coagulating the casein present in milk by using the enzyme rennet. The ripening in cheese is achieved due to the proteolytic and lipolytic activities of various microorganisms. The low moisture content of hard and semi-hard ripened cheese makes them susceptible to fungi compared to Bacteria . Soft and fresh cheese are spoiled easily due to their higher ph, moisture content, and lower salinity. The bacterial cheese spoilage is caused by clostridium spp., bacillus polymyxa., flavobacterium. Yeats are common cheese spoilage organisms e.g., candida spp., pichia spp ., geotrichum candidum., The mod spoilage by penicillium spp., Major pathogenic bacteria found in cheese are E.Coli., salmonella spp.,

22. YOGHURT Yogurt is a popular fermented dairy product produced by lactic acid bacteria, including Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. During yogurt production, these bacteria produce lactic acid, decreasing pH and causing milk protein to coagulate . Yogurt is a dairy product made by fermenting milk with a bacterial yogurt culture. It provides protein and calcium, and it may enhance healthy probiotic gut bacteria.

23. SPOILAGE OF YOGHURT Yogurt is a lactic acid fermented milk product that is produced by using symbiotic cultures of two Lactic acid bacteria ( Streptococcus thermophilus  and  Lb. delbrueckii  subsp . Bulgaricus ). Fruits and nuts added to yogurt for enhancement of flavor are the main sources of contamination. Molds and yeasts are the primary contaminants in yogurt.  The most common mold causing yogurt spoilage are  Aspergillus, Penicillium, Rhizopus, Fusarium,  and  Trichoderma. The most common yeasts causing yogurt spoilage are  Candida spp., Debaryomyces, Kluyveromyces, Torulopsis, and Saccharomyces spp. They are responsible for off-flavor, gas production, discoloration, etc. Molds and yeasts that cause yogurt spoilage leads to a decrease in acidity, leading to proteolysis and putrefaction by bacteria The common food-borne pathogens reported are  Escherichia coli, Staphylococcus aureus, Listeria monocytogenes,  and  Yersinia enterocolitica.

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