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INTRODUCTION

What is milk?

- Milk is an opaque white liquid produced by the mammary glands of mammals.

- It is should be free from colestrum.- It provides the primary source of nutrition for young mammals.- The early lactation milk is known as colostrum, and carries the

mother's antibodies to the baby.- It can reduce the risk of many diseases in the baby.- it contains significant amounts of saturated fat, protein and

calcium as well as vitamin C.- milk has a pH ranging from 6.4 to 6.8, making it slightly acidic.- In almost all mammals, milk is fed to infants through

breastfeeding- cow's milk has been processed into dairy products such as cream,

butter, yogurt, kefir, ice cream, and especially the more durable and easily transportable product, cheese.

- Modern industrial processes produce casein, whey protein, lactose, condensed milk, powdered milk, and many other food-additive and industrial products.

Types of milk

1) Pasteurised milk:-

- Milk or product heated to at least 63oc for 30 min or 71.5o c for not less than 15 sec.

- All the pasteurised milk and milk products should be cooled, immediately, to a temperature of 10o.

2) Sterilised milk:-

- Milk heated to a temperature of 115oc for 15 min.

- This milk show absence of albumin, i.e. negative turbidity test.

3) Flavoured milk:-

- This may contain Chocolate ,Coffee or any other edible flavour.

- This milk should be pasteurised ,sterilised or boiled.

4)Skimmed milk:-

- It means product prepared from milk from which almost all the fat has been removed mechanically.

- It shall have not more than 0.5% fat and 8.7% Solid Not Fat(SNF).

5) Standardised milk:-

- It means cow milk , buffalo milk , sheep milk , goat milk or combination of any of these milk that has been standardised to minimum of 4.5% fat by the abstraction or addition of Milk fat.

6)Recombined milk:-

- It means the homogenised product obtained from milk fat, non milk fat and water.

- Recombined milk should be pasteurised and should show a negative phosphate test.

Composition of milk

- Milk is a complex mixture of lipids, carbohydrates, proteins and many other organic compounds and inorganic salts.

- Macy, Kelly and Sloan list over 100 compounds in it.

- Milk contains a number of enzymes.

- Vitamins are present in good quantity.

COMPOSITION OF MILK

Name of species

Water Fat Protein Lactose Ash

Buffalow 84.2% 6.6% 3.9% 5.2% 0.8%

Cow 84.6% 4.6% 3.4% 4.9% 0.7%

Goat 86.5% 4.5% 3.5% 4.7% 0.8%

Human 87.5% 3.6% 1.8% 6.8% 0.1%

What are adulterants?

- Adulterants are chemical substances which should not be contained within any other substances(eg. food, beverages, fuel or pesticides)for legal or any other reasons.

- Adulterants may be intentionally added to increase the visible quantities and reduce the manufacturing costs.

- The addition of adulterants is known as “ADULTERATION”.

Why adulterants used in milk?

- To increase the quantity.

- To improve the lactometer reading.

- To improve the quality.

- To attract the customers.

Common Adulterants:-

- Cane sugar.

- Starch.

- Ammonium sulphate.

- Urea.

- Skimmed milk powder.

- Detergents.

- Hydrogen Peroxide (H2O2).

- Glucose.

- Sodium Chloride.- Pulverized soap.

Detection of adulterants:-

I. Detection of cane sugar

o Requirements:-

Resorcinol and concentrated HCl.

o Procedure:-a) Curdle an aliquot of the milk by adding a little concentrated

HCl(for 25 ml of milk usually 1 ml of concentrated HCl is required).

b) Let stand for about 10 minute and filter.c) To 5 ml of the modifed resorcinol-HCl reagent taken in a test

tube , add 1 ml of the filtered milk serum and mix.d) Place the test tube in boiling water bath for exactly 1 min.e) Withdraw the tube and observe the colour.

o Observation:-Apperance of deep red colour indicates presence of sucrose ,or a

ketose.

II. Detection of starch

o Introduction:-

Addition of starch also increases the Solid not Fat(SNF) content of milk.

o Requirements:-Iodine Solution

o Procedure:-a) Take about 5 ml of milk in a test tube.b) Bring to boiling condition and allow the test tube to cool to

room temperature.c) Add 1-2 drops of iodine solution to the test tube.

o Observation:-o Development of blue colour indicates presence of

starch ,which disappears when sample is boiled and reappear on cooling.

III. Detection of ammonium sulphate

o Introduction:-The presence of sulphate in milk increases the lactometer reading.

o Requirements:-Sodium hydroxide , sodium hypochlorite ,phenol.

o Procedure:-a) Take 1 ml of milk add 0.5 ml of 2% sodium hypochlorite and

0.5 ml of 5% phenol solution.b) Heat for 20 second in boiling water bath.

o Observation:-o Bluish colour turns deep blue in presence of ammonium

sulphate. The development of pink colour shows that the sample is free from Ammonium Sulphate.

IV. Detection of urea

o Introduction:-Urea is generally added in the preparation of synthetic milk to raise the SNF value.

o Requirement:-p – Dimethyl amino benzaldehyde (DMAB),HCl. 1.6% DMAB: Dissolving 1.6gm of p-Dimethyl amino benzaldehyde in 100ml of 10% HCl.

o Procedure:-5 ml of milk is mixed with 5ml of 1.6% DMAB and Observe the colour of the milk.

o Observation:-The control (normal milk) shows a slight yellow colour due to presence of natural urea.

V. Detection of skimmed milk powder

o Requirements:-- Liquid NH3 and concentrated HNO3

o Procedure:-a) Take 50ml of milk in centrifuge tube. Centrifuge at

1000 RPM for 30 minutes.b) Decant the supernatant milk carefully.c) Dissolve it in distilled water and add 2.5ml of liquid

NH3 and few drop of concentrated HNO3

d) Observe the change in colour.

o Observation:-- Orange colour shows the presence of skimmed milk

powder as adulterants.- Yellow colour shows the absence of skimmed milk

powder.

VI. Detection of detergents

o Requirements:-

- Bromocresol solution.

o Procedure:-- Take 5 ml of milk in a test tube and add 0.1 ml of

bromocresol.

o Observation:-- Appearance of voilet colour indicates the presence of

detergent in milk.

- Unadulterant milk shows faint violet colour.

VII. Detection of Hydrogen peroxide (h2o2)

o Requirements:-

- Paraphenylene diamine.

o Procedure:-a) Take 5 ml milk in a test tube.b) Add 5 drops of paraphenylene diamine and shake it

well.

o Observation:-- Change in the colour of milk to blue confirms

addition of hydrogen peroxide in the milk.

VIII. Detection of glucose

o Requirements:-- Modified barford’s reagent , Phosphomolybdic acid ,

acetate buffer.

o Procedure:-a) Take 1 ml of milk sample in a test tube.b) Add equal volume of acetate buffer and filter.c) Add 0.2 ml of filterate to 2.8 ml of water and 2 ml of

barford’s reagent.d) Heat the tube in boiling water for 4 minutes.

e) After cooling for 2 minutes add 3 ml of

Phosphomolybdic acid and mix the contents.

o Observation:-- Development of deep blue colour indicates the

presence of glucose.

IX. Detection of sodium chloride

o Requirements:-- 5% potassium chromate , 0.1N silver nitrate.

o Procedure:-- Take 2.0 ml of milk and add 1.0 ml of 5% potassium

chromate , 2.0 ml of silver nitrate.

o Observation:-- Apperance of red precipitate indicates the absence of

dissolved chloride in milk and appearance of yellow colour indicates presence of dissolve chloride.

X. Detection of pulverized soap

o Requirements:-- Phenolphthalein indicator.

o Procedure:-a) Take 10 ml of milk in a test tube , dilute it with

equal quantity of hot water.b) Add 1-2 drops of phenolphthalein indicator.

o Observation:-

- Development of pink colour indicates that the milk is

adulterated with soap.

RESULT

Thatipur govindpuri morar sanchi

Cane sugar Negative Positive Negative Negative

Starch Negative Positive Negative Negative

Ammonium sulphate

Negative Negative Negative Negative

Urea Negative Negative Positive Negative

Skimmed milk

Positive Negative Negative Negative

Detergents Positive Negative Negative Negative

Hydrogen peroxide

Negative Negative Negative Negative

Glucose Positive Negative Positive Negative

Sodium chloride

Negative Negative Negative Negative

Pulverized soap

Negative Negative Negative Negative

References

www.dairyforall.com/milk-adulteration.php www.ncbi.nlm.nih.gov/pmc/articles/PMC1710849/ McGee, Harold (2004). On Food and Cooking (Revised

Edition). Scribner. ISBN 0-684-80001-2. Information on milk by Parmalat Introduction to Dairy Science and Technology: Milk History,

Consumption, Production, and Composition http://www.sciencebyjones.com/MILK_NOTES.HTM

Giblin, James. Milk: The Fight for Purity. Thomas Y. Crowell, 1986.

Hui, Y.H., ed. Encyclopedia of Food Science and Technology. John Wiley and Sons Inc., 1992.

Kroschwitz, Jacqueline I. and Mary Howe-Grant, ed. Encyclopedia of Chemical Technology, 4th edition. John Wiley and Sons Inc., 1993

http://www.madehow.com/Volume-4/Milk.html

Dairy Farmers of Ontario. http://www.milk.org . International Dairy Foods Association. http://www.idfa.org . National Milk Producers Federation. http://nmpf.org . McGraw-Hill Encyclopedia of Science and Technology,

McGraw-Hill, 1997.

An assignment on: MILK ADULTERATION

Submitted to: Submitted by:

Rahul Lakhmani

B.Sc Biotech 3rd yr

ROLL NO:66374