Minerals

Minerals:  Although present in small quantities, exert considerable influence on the physico- chemical and nutritive profile of milk  Part of the mineral salts occur in true solution, while others are in colloidal state All 22 minerals considered essential to the human diet are present in milk. These include 3 families of salt: 1.Na,K,Cl: these free ions are negatively correlated to lactose to maintain osmotic equilibrium of milk with blood

2. Ca,Mg,P(i) & citrate: This group consists of 2/3 Ca,1/3 Mg,1/2 P(i) and <1/10 citrate in colloidal (non-diffusible) form & present in casein micelle. 3. Diffusible salts of Ca,Mg, citrate & Po4 – these salts are pH dependant and contribute to overall Acid base equilibrium of milk

THE MINERAL CONTENT OF FRESH MILK Mineral

Content Per litre

Sodium (mg)

350-900

Potassium (mg)

1100-1700

Chloride (mg)

900-1100

Calcium (mg)

1100-1300

Magnesium (mg)

90-140

Phosphorous (mg)

900-1000

Zinc (ug)

2000-6000

Copper (ug)

100-600

Manganese (ug)

20-50

Iodine (ug)

260

Mineral

MINERAL CONTENT OF MILK Content Per litre

Fluoride (UG)

30-220

Selenium (ug)

5-67

Cobalt (ug)

0.5-1.3

Chromium (ug)

8-13

Molybdenum (ug)

18-120

Nickel (ug)

0-50

Silicon (ug)

750-7000

Vanadium (ug)

Tr-310

Tin (ug)

40-500

Arsenic (ug)

20-60

Nutritional value:  Minerals have a high NV.  Consumption of modest ~60 g of SMP provides RDA for Ca and P(75%)  Dietary ca widely recognized a key factor in ˜ Healthy bone development in foetus & Children. ˜ Development of osteoporosis in post – menopausal women.  Milk is an excellent source of dietary Ca

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Its association with phosphorylated caseins improves its absorption from the GIT. Phosphopeptides released during digestion of casein increases the conc. of soluble Ca in the intestine - enhanced bioavailability Milk is also rich in a wide range of elements Trace element requirements significantly contributed by milk in the form of Mg, Zn, Se,Mb and I.

Minor Milk Constituents: Phospholipids (0.2-1.0%)  Present in FGM & Milk serum.  Three types viz., lecithin, cephalin and sphingomyelin  Lecithin ~forms an imp. Constituent of FGM ~contributes to the richness of flavor of milk and other dairy products ~ Highly sensitive to oxidative deterioration giving rise to oxidative/ metallic flavors.

PL are excellent emulsifying agents and serve to stabilize milk fat emulsion Cholesterol (0.25-0.40%)  In complex formation with proteins in the nonfat portion of milk. Present as part of the FGM complex in fat portion of milk Pigments i. Fat soluble- carotene, xanthophyl ii. water soluble – riboflavin 

Carotene is responsible for the yellow colour of milk, cream, butter, ghee and other fat rich dairy products.  Acts as an antioxidant  Precursor of Vit.A.  Has two forms alpha and Beta, the former yields one while latter yields two molecules of Vit.A.  Dairy animals differ in their capacity to transfer carotene from feed to milk fat. 

This varies with Species,breed and individuality.  cows in general and some breeds in particular (Guernsey, jersey) can transfer more carotene from feed to milk fat compared to buffaloes.  Buffalo milk is whiter in colour (carotenoid content 0.25-0.48ug/g vs. cow milk ~30ug/g)  Riboflavin, besides being a Vit. is a greenish yellow pigment- gives characteristic colour to whey 

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Enzymes: Milk is rich in native enzymes About 50 different enzyme activities are reported- only a small number has significance. Lipoprotein Lipase Principal lipase in milk catalyzes the hydrolysis of TG to FFA Present in appreciable quantities in freshly drawn milk. Pronounced reactions lead to production of soapy, bitter, rancid and unclean flavors

Spoilage by this enzyme prevented by two factors: ~ FGM-acts as a physical barrier ~ Heat treatment readily destroys lipase  Spontaneous lipolysis rare and occurs due to factors like , ~ Stage of lactation ~Season ~ diet ~ Plane of nutrition 

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Plasmin Major milk proteinase Has a trypsin like activity Identical to blood plasmin and conc in milk associated with blood conc. High milk plasmin is seen in conditions like ~ Early lactation ~ Late lactation ~ Udder diseases

(Leakage of blood components into milk)  Index of high plasimn activity ~ High levels of gamma casein ~ Bacteriologically sound milk  At neutral pH heat stable  Survives pasteurization / UHT treatment Lactoperoxidase  Present in high concentrations  Catalyzes transfer of O from H O to other 2 2 2 substrates like Thiocyanate

Has potential to catalyze oxidation of USFA leading to development Of oxidized flavour  Extraneous addition of SCN and H o in milk – 2 2 acts as a powerful bactericide.  Short term preservation of milk in developing countries where refrigeration is scarce. Xanthin Oxidase  Catalyzes Non- Specific oxidation of dairy products  Overall significance is not high. 

Alkaline Phosphatase  Completely inactivated by pasteurization  used as index of efficiency of pasteurization Vitamins  Essential for many life processes  Substantial quantities found in milk ~ Fat soluble –A,D,E,K ~ water soulble B1,B2, B6, B12, niacin, pantothenic acid, biotin, folic acid

Factors affecting concentration. ~ Seasonal changes ~Breed ~ Diet  Vitamins readily affected by ~ Light ~ Processing (Deteriorates,A,B2, C) 

~ Fat soluble – stable

VITAMIN CONTENT OF MILK Vitamin

Contents per litre

A (ug RE)

400

D (IU)

40

E (ug)

1000

K (ug)

50

B1 (ug)

450

B2 (ug)

1750

Niacin (ug)

900

B6 (ug)

500

Pantothenic acid (ug)

3500

Biotin (ug)

35

Folic acid (ug)

55

B12 (ug)

4.5

C (mg)

20

Urea  Responsible for Seasonal variation in heat stability  Conc. In milk controlled by conc. In blood which in turn is controlled by diet. Mechanism by which urea influences heat stability : urea decompose on heating to yield isocyanate which reacts with free SH groups in WP and/or Kappa casein  High levels of urea are associated with very stable milk.

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Milk is considered a near complete single food in nature because it contains almost all essential nutrients required for growth and development in adequate and assimilable forms. Considered as chief protective food because it has abundant vitamins and calcium

Colostrum Syn. Biestings  First secretion drawn immediately after parturition  Thick viscid fluid differing greatly in composition from that of milk obtained a week after calving  Characterized by: ~ High proportion of albumin & globulin ~higher ash content ~ lower lactose content 

The change from colosrtrum to milk is gradual and there is a progressive/ regular fall in: ~Chloride ~ Ash ~ Total Nitrogen ~ Casein ~ Albumin + Globulin ~ Dry matter ~ Specific gravity ~ TA  FP Practically constant  Lactose variable & Fat irregular 

The most striking difference between milk and colostrums is the high globulin content which causes milk to coagulate on boiling ;also influenced by salt imbalance and lower heat Stability.  Iron content of colostrum is -10-17-times higher than normal milk.  Higher proline content of globulin.  Significant from the aspect of Hb production in newly born.  Fat of colostrum compared to milk has :

˜ 9 times Carotone ˜ 8 times Vit A ˜ two times Vit D Functions:  Hb production in rapidly growing new borns  Passive immunity conferred by transfer of maternal antibodies to offspring's  Facilitates faecal excretion

Composition of colostrums

Constituents

Range of Occurrence

Water

75-78%

Total Protein

16-18%

Casein

4-5%

Albumin & Globulin

12-13%

Fat

4-5%

Lactose

2-2.5%

Mineral Matter

1-1.6%

Specific gravity

1.046%- 1.079

Total Solids

22-25%