role of microbes in dairy industary
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8/4/2019 Role of Microbes in Dairy Industary
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(Session 2011-2012)
Submitted To Presented By
Department of Biotechnology Shubham Dwivedi
Megha Mazumdar
SangitaAmit Kumar Sharma
Microbes - Friend or FoeRole of Microbes in Dairy Industry
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Introduction
Milk: the first food for young mammals
Provides high quality protein, vitamins and minerals and is a source of
energy Worldwide many mammalian species are used to produce milk and
milk products
Example Goats, sheep, horses, yaks
However, our focus will be on milk from dairy cows
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Fluid Milk
Colloidal dispersion of the protein caesin and the wheyproteins. It is an emulsion with fat globules suspended inthe water phase
Composed mainly of water
87-89%
Milk solids make up the other 12-13%
Solids include the carbohydrates, lactose, fat, proteinand minerals
Solids-not-fat
Excludes the fat and includes the caesin, whey, lactose,proteins, minerals
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Potential Pathogens in Milk
Listeria
Salmonella
E. Coli
Campylobacter
Yersinia
Staphylococcus aureus
Clostridium
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Listeria Monocytogenes
Soil, dust, mud and animals
Can multiply at refrigeration temperatures
Can cause meningitis and septicaemia
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Salmonella
Over 2000 types
Cows, poultry, pigs
Diarrhoea, cramps, vomiting and fever
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Escherichia coli
Rare, infective dose 10 cells
Faecal material into milk
Abdominal pain and severe diarrhoea
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Clostridium perfringens
Environment, human and animal intestines
Ingestion of large numbers cause illness
Cramps and diarrhoea
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Source of potential pathogens
The cow coat, udders, faecal contamination
Environmental - Soil, bedding, food
Mastitis
Milk handling equipment
Producer
Prolonged holding of milk in silo
Mixing old and new milk
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Hygiene procedures
Daily cleaning of milking apparatus
Farmer washing hands / wearing gloves
Not milking cows with mastitis
Not feeding hay/ silage while milking
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Temperature
5C 2,600
10C 11,600
12.5C 18,800
15.5C 180,000
20C 450,000
Tested on arrival
Below 5C
Organisms and temperature influence bacterial proliferation
Number of bacteria per ml after 24 hours
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Animal cell counts
Test for low level of animal cells
Epithelial cells and white blood cells
Mastitis
High level indicates sub clinical mastitis
Pathogens Streptococcus Aureus
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Low levels of bacteria
Resazurin test
Changes colour by actively proliferating bacteria
Blue, Lilac = Low level of bacteria
Pink, white = High level - Retest
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Raw Milk Quality
No added water
No antibiotic residues Starter cultures
No taints
Good compositional quality
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Typical Milk Composition
Fat 4%
Protein 3.5%
Lactose
(Milk Sugar)
5%
Vitamins/
Minerals
0.5%
Water 87%
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Other Dairy Products
Skimmed Milk
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Pasteurisation
Discovered by Louis Pasteur
Milk is heated to 60-63oC for at least 15 seconds.
Cooled immediately.
Pasteurisation kills harmful bacteria (Pathogens).
Mycobacterium paratuberculosis.
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Pasteurizing
Low Temperature Longer Time (LTLT)
Heats milk to at least 145 degrees C for at least 30 minutes
Can cause a cooked flavor
Not used by some milk plants for fluid milk products
High Temperature/Short Time (HTST)
Heats milk to at least 161 degrees C for at least 15 secondsMilk is immediately cooled to below 40 degrees C andpackaged in plastic jugs or plastic coated cartons
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Homogenization
Prevents the cream from rising to the top
A homogenizer forces milk under high pressure through a
valve that breaks up butterfat globules to such a small size thatthey will not coalesce (stick together)
Does not affect the nutrion or quality
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Beverage Milk
Most raw milk fat content is 4% or higher
Most beverage milk is 3.4%
Lower fat contents- 2%, 1%, Skim
These products are produced by partial or complete skimming
and then adding cream back to achieve the final desired fatcontent
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Nutritional Qualities
Vitamins may be added
A & D most often due to their loss
A during fat separation and heating
D because it is not present in milk Supplemeted in the form of a water-soluble emulsion
Many states have milk standards that require the addition of
milk solids These represent the natural mineral, protein, and sugar
portion of nonfat dry milk
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Quality Control
Numerous test on raw and pasteurized product
Microbial organisms are tested by using the standard platecount (SPC) and ropey milk test
Equipment used to analyze butterfat and solids-not-fat iscalibrated on a regular basis to ensure consistency
All products have a sell-by date
Samples of the products packaged each day are saved toconfirm they maintain their freshness 7 days after the sell-bydate
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Phosphatase test
To test pasteurisation process efficacy
To check no raw milk contamination
Phosphatase is an enzyme
Inactivated by pasteurisation
Any remaining phosphatase activity = pasteurisation process
not effective
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Milk to curd
Milk to cheess
Starter cultures added
Bacteria
Lactose Lactic Acid
Friendly Microbes
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Examples of Starter cultures
Blue stilton
Lactobacillus lactis subsp diacetylactis
Leuconostoc mesenteroides subsp cremori
White stilton
Lactobacillus lactis subsp lactis
Lactobacillus lactis subsp cremoris
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Lactococcus lactis ssp cremoris
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Bacteria in Yogurt
Lactobacillus bulgaricus
Streptococcus thermophilus
Lactobacillus acidophilus
Bifidobacterium
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Why do we need friendly bacteria? Acidification of cheese by starter bacteria
Results in optimum lactic acid content
Allows protein coagulation by rennet = curd
Stir and Cut the curd release whey
Fat retained in the coagulum
Water drains out in the whey
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Other effects of Bacteria
Produce gases Edam
Produce flavour and aroma
Produce enzymes
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Other Microbes in Cheese
Moulds: Penicillium camembertiiPenicillium roquefortii
Added to affect flavours
Others: MicrococcusYeastsMoulds
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Blue Stilton Production
Raw Milk (5C)
Fat adjustment (Standardisation)
Pasteurisation (72C, >15 secs)
Transfer to Vat (30C)
Add Starter Culture (Bacteria)
Add Blue Mould
Add Rennet (To coagulate protein)
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Blue Stilton Production
Acid development and curd formation
Drain whey off curd
Salt and mill curd
Fill hoops
Drainage (20C)
Cool, de-hoop and cling film (10C)
Remove cling film
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Conclusion
Pathogens who effect milk quality
Source of Milk
Effect of Human Life
Milk Quality
How do we eliminate any pathogen in raw milk
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.
Thank to All of You
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