Defination of Milk Milk may be defined as the whole, fresh, clean, lacteal secretion obtained by the complete milking of one or more healthy milch animals, excluding that obtained within 15 days before or 5 days after calving or such periods as may be necessary to render the milk practically colostrums-free, and containing the minimum prescribed percentage of milk fat and milk solid not fat
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Defination of Milk
Milk may be defined as the whole, fresh, clean, lacteal secretion obtained by the complete milking of one or more healthy milch animals, excluding that obtained within 15 days before or 5 days after calving or such periods as may be necessary to render the milk practically colostrums-free, and containing the minimum prescribed percentage of milk fat and milk solid not fat
• Major milk serum protein. about 50% of the serum protein and 8% of the protein in milk.
• There is no β -Lactoglobulin present in human milk.
• β - Lactoglobulin can be irreversibly denatured by heat.
• This stress causes rupture of intr-amolecular disulfide bonds and precipitation
• Transport of hydrophobic molecules : vitamin A, vitamin D, fatty acids (C14; C16; C18, C18:1)
• If milk is heated to over 60 °C, denaturation is initiated where the reactivity of the sulphur-amino acid of β-lactoglobulin plays a prominent part.
• Sulphur bridges start to form
1.Between the β-lactoglobulin them selve molecules,
2.Between β-lactoglobulin molecule and a κ-casein
3.Between β-lactoglobulin and α-lactalbumin. • At high temperatures, sulphurous compounds such
as hydrogen sulphide are gradually released. • These sulphurous compounds are responsible for
the “cooked” flavour of heat treated milk.
Immunoglobulins and related minor proteins
• Immunoglobulins are antibodies synthesised in response to stimulation by specific antigens.
• They are specifically present in blood. • Their content in cows’ milk is low, but some of
them are present in higher levels in colostrum and human milk.
• They can also act against “particles” such as bacteria, viruses and even fat globules, and flocculate them, a reaction called agglutination
• Serum Proteins
• Comes from blood
• Role in the transport of bile salts, fatty acids
• Mambrane proteins• Membrane proteins are a group of proteins that
form a protective layer around fat globules to stabilise the emulsion
• Some of the proteins contain lipid residues and are called lipoproteins.
Denatured proteins• As long as proteins exist in an environment with
a temperature and pH within their limits of tolerance, they retain their biological functions.
• If they are heated to temperatures above a certain maximum their structure is altered.
• The same thing happens if proteins are exposed to acids or bases, to radiation or to violent agitation.
• The proteins are denatured and lose their original solubility.
•Milk enzymes Milk enzymes
• 60 enzymes known
• Origin
Milk enzymesMilk enzymes
•
• Cells
• Leucocytes
• Bacteria
- endogenous
- exogenous ?
Lipases are enzymes that degrade fats. The major lipase in milk is lipoprotein lipase. It is associated with the casein micelle. Agitation during processing may bring the lipase into contact with the milk fat resulting in fat degradation and off-flavors. Pasteurization will inactivate the lipase in milk and increase shelf life.
ENZYMES
Proteases
The major protease in milk is plasmin.
Some proteases are inactivated by heat and some are
not. Protein degradation can be undesirable and result in
bitter off-flavors, or it may provide a desirable texture to
cheese during ripening. Proteases are important in
cheese manufacture, and a considerable amount of
information is available in the cheese literature.
Alkaline phosphatase is a heat sensitive enzyme in milk that is used as indicator of pasteurization. If milk is properly pasteurized, alkaline phosphatase is inactivated. Lactoperoxidase most heat-stable enzymes found in milk. When combined with hydrogen peroxide and thiocyanate, has antibacterial properties. It is suggested that the presence of lactoperoxidase in raw milk inhibits the disease causing microorganisms (pathogens) present in milk.
The milk fat exists as small globules or droplets dispersed in the milk serum,
Their diameters range from 0,1 to 20 µm (1 µm = 0,001 mm).
The average size is 3 – 4 µm and there are some 15 billion globules per ml.
The emulsion is stabilised by a very thin membrane only 5 – 10 nm thick (1 nm = 10–9 m ) which surrounds the globules and has complicated composition.
MILK FAT
Milks lipids 2% to greater than 50%
Source of essential fatty acids (especially linoleic
acid, &) and fat soluble vitamins (A, D, E, K)
Flavour and rheological properties of dairy products
and foods in which they are used flavour of milk fat
is superior to that of other fats. Milk fats, especially
ruminant fats, contain a very wide range of fatty
acids: more than 400
FAT GLOBULE
Milk lipids (Fat)Milk lipids (Fat)
• 3.5 - 4.5% (i.e. 35-45 g/l) for bovine milk
•Simple and complex mixture
Neutral Lipids 98.4 %
Polar Lipids1.1 %
Sterols0.5 %
MILK FAT
Milk fat consists ofo triglycerides (the dominating components), o di- and monoglycerides, o fatty acids, o sterols, o carotenoids (giving the yellow colour of
the fat)
• and vitamins (A, D, E, and K)
Principle fatty acids in milk
Milk : composition of neutral lipidsMilk : composition of neutral lipids
Unsaturated fatty acidsoleic acids.• fatty acids affects the hardness of the fat. • Fat with a high content of high-melting fatty
acids, such as palmitic acid, will be hard;• but on the other hand, fat with a high content of
low-melting oleic acid makes soft butter.
Iodine Value
Iodine value states the percentage of iodine that the fat can bind.
Iodine is taken up by the double bonds of the unsaturated fatty acids.
Since oleic acid is by far the most abundant of the unsaturated fatty acids, which are liquid at room temperature, the iodine value is largely a measure of the oleic-acid content and thereby of the softness of the fat.
Iodine value of butterfat normally varies between 24 and 46.
Conjugated Linoleic acid (CLA)
Cancer
CLA in your diet could reduce tumors
Breast Colorectal
Lung Skin
Stomach Cardiovascular disease
High blood pressure
High Cholesterol and triglycerides
Osteoporosis
Dodhi
FarmersSub Center
Main center
Factory
VMC
Milk CollectionMilk Collection
VMCSub CSub C
Main C
Collecte centerCollecte center
Problems related to milk collectionProblems related to milk collection Highly fluctuation in milk price Seasonal variation Lack of direct approach to farmers Social attachment of Dodhi with farmers
o Advanceso Emergency o High price
Lack of roads Lack of infrastructure Preservation of milk Adulteration
o Vegetable oilso Fresh or Pasteurized creamo Glucoseo Sugaro Ureao Starcho Detergento Weigh Powdero Salto Fermented Milk