Milk Adulteration and Milk Properties
-
Upload
nagaraj-kh -
Category
Documents
-
view
240 -
download
0
Transcript of Milk Adulteration and Milk Properties
-
7/27/2019 Milk Adulteration and Milk Properties
1/22
Milk Adulteration
-
7/27/2019 Milk Adulteration and Milk Properties
2/22
What is Food Adulteration?
Food adulteration - quality is lowered or affected
addition of substances which may be injurious to health
removal of substances which are nutritious.
Definition:
Act of intentionally debasing the quality of food offered for sale either
by the admixture or substitution of inferior substances or by the
removal of some valuable ingredient.
-
7/27/2019 Milk Adulteration and Milk Properties
3/22
When you state that a food is adulterated?
If any inferior or cheaper substance has been substituted wholly or in part,
If any constituent of the article has been wholly or in part removed
If the food has been prepared, packed or kept under insanitary conditions
If the food consists in part filthy, rotten, decomposed or diseased animal orvegetable or is infested with insects
If the article contains any poisonous ingredient
If the food has un-prescribed colouring substance or the colouring substanceis in excess of the prescribed limits.
If the food contains any prohibited or excessive preservatives.
If the quality or the purity of the article falls below prescribed standard
As per Prevention of Food Adulterant Act 1954
-
7/27/2019 Milk Adulteration and Milk Properties
4/22
Types of milk adulterants
1. Addition of water
2. Addition of colouring matter
3. Addition of preservatives
4. Addition of thickening agents
-
7/27/2019 Milk Adulteration and Milk Properties
5/22
Addition of water
Increase the quantity
most difficult to detect
pure - does no harm other than to defraud the consumer
impure - drawn from wells near manure heaps, in
barnyards, it may prove fatal.
-
7/27/2019 Milk Adulteration and Milk Properties
6/22
Addition of colouring matter
The normal whiteness and opacity of milk is due to its fat globules.
Carotene
Annotto is the commonest dye used to impart a yellow colour to milk,cream, and butter.
Annotto - seeds of a tropical American tree (Bixa orellana).
It is detected by allowing the milk to stand in a tall glass, where thelower stratum will contain the pigment associated with the caseininstead of remaining colourless, while the naturally yellower creamfloats on top.
The cow's milk red or pink, and it may be so stained by traces of blood
-
7/27/2019 Milk Adulteration and Milk Properties
7/22
Addition of preservatives
To keep them from souring.
To increase the shelf life or keeping quality of milk.
Preservatives: sodium bicarbonate, borax, or boric acid.Salicylic acid and formaldehyde are less often used.
In small quantities they do not affect its taste or hurt thedigestion of adults, but they may be injurious and evenfatal to infants, and their use should never be tolerated.
-
7/27/2019 Milk Adulteration and Milk Properties
8/22
Addition of thickening agents
To bring back the consistency of milk to normal
To raise the specific gravity
To adjust the Solid Non Fat content of the milk
Starch, Flour, arrowroot, chalk, carbonate of magnesia,
Sugar, etc
-
7/27/2019 Milk Adulteration and Milk Properties
9/22
Detection of Neutralizers in milk
Rosalic acid test (Soda Test) Test for detection of hydrogen peroxide
Test for detection of formalin
Test for detection of sugar in milk
Test for detection of starch
Test for detection of glucose Phosphomolybdic or Barford Test
Diacetic test
Test for detection of urea
Test for detection of ammonium sulphate
Test for detection of salt
Test for detection of pulverized soap
Detection of detergents in milk
Detection of water in milk
Detection of skim milk powder in milk
Detection of vegetable fat in milk
Detection of buffalo milk in cow milk
Detection of benzoic and salicylic acid in milk
Detection of borax and boric acid in milk
Test to detect milk adulterants
-
7/27/2019 Milk Adulteration and Milk Properties
10/22
Mixture of water, pulverized detergent or soap, sodium hydroxide,vegetable oil, salt and urea
Synthetic milk
Differentiating
tests
Genuine Milk Synthetic Milk
Physical tests
Colour White White
Storage On storage, it remains white It turns pale yellow after some time
Texture When rubbed on the palm, it doesnt form
foam
When rubbed on the palm, foam formation
noticed.
pH 6.6 to 6.8 1011 (Highly alkaline)
Fat 4.55.0% 4.55.0%
Solids Not Fat 89% 89%
Chemical tests
Heat No change in colour on heating It turns yellow on boiling
Urea test Pale yellow colour develops Dark yellow colour develops
-
7/27/2019 Milk Adulteration and Milk Properties
11/22
Milk allergy
adverse reactions - immunoglobulin E (IgE) antibodies
to one or more protein fractions of milk, whether
belonging to the casein or whey protein group.
Proteins belonging to the casein group are heat-stable, i.e., they cannot be broken down using heat.
Thus, individuals allergic to casein proteins cannot
tolerate any cow's milk, including boiled milk.
whey proteins can be broken down by heat.
occur in any individual. (young children, although
people can develop milk allergy at any age)
-
7/27/2019 Milk Adulteration and Milk Properties
12/22
Milk intolerance
Milk intolerance occurs as a result of the decrease or
absence of an enzyme, called lactase, in the
gastrointestinal tract that is required to metabolise the
milk sugar lactose.
mainly seen in individuals over the age of five.
Particularly black children partially or completely lose
this enzyme.
-
7/27/2019 Milk Adulteration and Milk Properties
13/22
localized, cutaneous, and mostly benign infection
caused by a DNA virus of the genus Parapoxvirus.
common in cattle worldwide.
Infections in cattle are also known as bovine papular stomatitis. Human disease is contracted through direct transmission (ie,
handling of infected cow teats, calf muzzles, or other sites ofactive bovine infection) or through indirect transmission (ie,handling of virally contaminated objects).
The course of milker's nodule is usually self-limited, running from14-72 days, with infrequent systemic symptoms and little or noscarring.
Milker's nodule
-
7/27/2019 Milk Adulteration and Milk Properties
14/22
Milk Properties
Milk proteins- consist mainly of casein, b -lactoglobulin, a -lactalbumin, etc.
Casein exists only in milk and is found in the form of a calcium caseinate-phosphate complex.
It is present in the colloidal state.
8 per cent of the total protein in milk. Casein itself is composed of a , b , g fractions.
b -lactoglobulins and a -lactalbumin are also known as whey or serum-proteins. They are also present in the colloidal state and are easily coagulableby heat.
Phospholipids:three types of phospholipids, viz. Lecithin, cephalin andsphingomylin. Lecithin, which forms an important constituent of the fat globule membrane,
contributes to the richness of flavour of milk.
highly sensitive to oxidative changes, giving rise to oxidized/ metallic flavours.
Phospholipids are excellent emulsifying agents, and no doubt serve tostabilize the milk fat emulsion.
-
7/27/2019 Milk Adulteration and Milk Properties
15/22
Density and Specific Gravity:
Milk is heavier than water.
The average specific gravity ranges
cow milk -1.028 to 1.030 for, buffalo milk -1.030 to 1.032
skim milk - 1.035 to 1.037 for.
Freezing point of milk Milk freezes at temperatures slightly lower than water due to the
presence of soluble constituents such as lactose, soluble salts,etc.,
Indian cow milk - 0.5470C (31.020F) and
buffalo milk - 0.5490C (31.010F).
Milk Properties
-
7/27/2019 Milk Adulteration and Milk Properties
16/22
Enzymes: 1) Analase (diastase)starch splitting,
2) Lipasefat splitting, leading to rancid flavour,
3) Phosphatecapable of splitting certain phosphoric acid esters (basis of phosphatasetest for checking pasteurization efficiency);
4) Pro-teaseprotein splitting;
5) Peroxidase and Catalasedecomposes hydrogen peroxide.
Vitamins:
Fat-soluble vitamins A, D, E and K; and
Water-soluble vitamins of the B-complex group (such as thiamine or B1, riboflavin or B2,pantothenic acid, niacin, pyridoxine or B6, biotin, B12, folic acid, etc.)
PH: cow milk - 6.4 to 6.6
buffalo milk - 6.7 to 6.8.
Higher pH values for fresh milk indicate udder infection (mastitis) and lower values,bacterial action.
Milk Properties
-
7/27/2019 Milk Adulteration and Milk Properties
17/22
Pigments:These are 1) fat soluble, such as carotene andxanthophyll, and
2) water soluble, such as riboflavin.
Carotene is the colouring matter of all green leaves, where it ismasked by chlorophyll. Carotene (the pure substance of whichhas a reddish-brown colour) is fat soluble and responsible for theyellow colour of milk, cream, butter, ghee and other fat-rich dairyproducts. Besides contributing to the colour of cow milk, caroteneacts as an anti-oxidant and also as a precursor of vitamin A.
Riboflavin, besides being a vitamin, is a greenish-yellowpigment, which gives the characteristic colour to whey.
Milk Properties
-
7/27/2019 Milk Adulteration and Milk Properties
18/22
Spoilage of Milk
-
7/27/2019 Milk Adulteration and Milk Properties
19/22
Milk
Rich source of nutrients
Also an efficient vehicle for a variety of pathogens
Sources of infection or contamination of milk
Dairy animal
Human handler or
Environment,
e.g., contaminated vessels, polluted water, flies, dust, etc.
-
7/27/2019 Milk Adulteration and Milk Properties
20/22
Spoilage occurs when microorganisms degrade the carbohydrates,
proteins, fats of milk and produce noxious, end products.
Spoilage of Milk and Milk Products
-
7/27/2019 Milk Adulteration and Milk Properties
21/22
Spoilage type Organisms involved Signs of spoilage
Souring Lactobacillus sp.
Streptococcus sp.
Sour milk,
curd formation
Sweet curdling Bacillus sp.
Proteus sp.
Micrococcus sp.
Alkaline pH
Curd formation
Gas production Clostoridium sp.
Coliform bacteria
Explosion of curds
Ropiness Alcaligenes sp.,Klebsiella
sp.,Enterobacter sp.
Stringy or slimy milk
Red rot Serratia marcescens Red colaration
Gray rot Clostridium sp. Gray colaration, Foul smell
Dairy mould Penicilium sp.,Geotrichum sp. Mouldy appearance
Different types of Spoilage of Milk and Milk Products
-
7/27/2019 Milk Adulteration and Milk Properties
22/22
Flavour of Milk
The flavour of milk is also due to the short chain fatty acidsproduced, particularlybutyric acid.
Acid/sourflavour - lactic acid bacteria which ferment lactose.
Fruityflavours may arise due to psychrotrophs such as Pseudomonasfragi.
Bitter or putrid- caused by psychrotrophic bacteria which produceprotease. It is the proteolytic action of protease that usually causesspoilage in milk.
Maltyflavours - caused by Streptococcus lactisvar. maltigenesand ischaracterized by a corn flakes type flavour.
Ropymilk is also caused by bacteria, specifically those which produceexopolysaccharides.