Role of Microbes in Dairy Industary

8/4/2019 Role of Microbes in Dairy Industary

1/34

(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

1


2/34

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

2


3/34

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

3


4/34

Potential Pathogens in Milk

Listeria

Salmonella

E. Coli

Campylobacter

Yersinia

Staphylococcus aureus

Clostridium

4


5/34

Listeria Monocytogenes

Soil, dust, mud and animals

Can multiply at refrigeration temperatures

Can cause meningitis and septicaemia

5


6/34

Salmonella

Over 2000 types

Cows, poultry, pigs

Diarrhoea, cramps, vomiting and fever

6


7/34

Escherichia coli

Rare, infective dose 10 cells

Faecal material into milk

Abdominal pain and severe diarrhoea

7


8/34

Clostridium perfringens

Environment, human and animal intestines

Ingestion of large numbers cause illness

Cramps and diarrhoea

8


9/34

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

9


10/34

Hygiene procedures

Daily cleaning of milking apparatus

Farmer washing hands / wearing gloves

Not milking cows with mastitis

Not feeding hay/ silage while milking

10


11/34

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

11


12/34

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

12


13/34

Low levels of bacteria

Resazurin test

Changes colour by actively proliferating bacteria

Blue, Lilac = Low level of bacteria

Pink, white = High level - Retest

13


14/34

Raw Milk Quality

No added water

No antibiotic residues Starter cultures

No taints

Good compositional quality

14


15/34

Typical Milk Composition

Fat 4%

Protein 3.5%

Lactose

(Milk Sugar)

5%

Vitamins/

Minerals

0.5%

Water 87%

15


16/34

Other Dairy Products

Skimmed Milk


17/34

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.

17


18/34

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

18


19/34

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

19


20/34

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

20


21/34

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

21


22/34

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

22


23/34

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

23


24/34

Milk to curd

Milk to cheess

Starter cultures added

Bacteria

Lactose Lactic Acid

Friendly Microbes

24


25/34

Examples of Starter cultures

Blue stilton

Lactobacillus lactis subsp diacetylactis

Leuconostoc mesenteroides subsp cremori

White stilton

Lactobacillus lactis subsp lactis

Lactobacillus lactis subsp cremoris

25


26/34

Lactococcus lactis ssp cremoris

26


27/34

Bacteria in Yogurt

Lactobacillus bulgaricus

Streptococcus thermophilus

Lactobacillus acidophilus

Bifidobacterium

27


28/34

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

28


29/34

Other effects of Bacteria

Produce gases Edam

Produce flavour and aroma

Produce enzymes

29


30/34

Other Microbes in Cheese

Moulds: Penicillium camembertiiPenicillium roquefortii

Added to affect flavours

Others: MicrococcusYeastsMoulds

30


31/34

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)

31


32/34

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

32


33/34

Conclusion

Pathogens who effect milk quality

Source of Milk

Effect of Human Life

Milk Quality

How do we eliminate any pathogen in raw milk

33


34/34

.

Thank to All of You

34

Documents

Role of Microbes in Dairy Industary