Does boiling affect calcium, proteins and vitamins present in milk?

Milk is heat treated (Pasteurized) at the Dairy to kill any pathogenic micro-organisms that may be present without affecting its nutritional quality. But milk boiling (100 degrees C) in houses causes changes in its constituents. The higher the temperature and the longer the exposure to heat the greater the changes.

The Solubility of calcium phosphate is very temperature-dependent. Unlike most compounds, the solubility of calcium phosphate decreases with temperature. This means that heating causes precipitation of calcium phosphate in the micelle, while cooling increases its concentration. After cooling, the reaction is readily reversible, but after heating to high temperatures, the reversibility is more sluggish and incomplete.

The changes at high temperature imply that the milk becomes more acid and pH drops.

Major protein, Casein (2.8 per cent) is not considered denaturable by heat within normal ranges of pH, salt and protein content.

Whey proteins (0.7 per cent), on the other hand, particularly Beeta-Lactoglobulin which makes up about 50 per cent of the whey proteins, are fairly heat sensitive. Denaturation begins at 65 degrees C and is almost total when whey proteins are heated to 90 degrees C for five minutes.

For whey proteins heat denaturation is an irreversible reaction. The randomly coiled proteins “open up”, and Beta-Lactoglobulin in particular is bound to the alpha casein fraction by sulphur bridges.

Milk is an important source of A, D and group B vitamins. The fat soluble vitamins are very thermo stable and their level is not lowered by heat treatment. However, when milk is fortified with vitamin A, the relative loss seems to increases.

Losses of vitamins mainly concern Vitamin C and some of the group B vitamins. The loss of Vitamin C as such is generally of minor importance, as milk is not an important source of this vitamin, but it may influence the Nutritional value anyway. The breakdown of Vitamin C is connected with that of vitamin B12 and protects folic acid from oxidation.

DR. K. ANBARASUDEPUTY MANAGER (DAIRY BACTERIOLOGY)
TAMIL NADU CO-OPERATIVE MILK PRO

Source: http://www.hindu.com

Study Shows Vitamins Don't Prevent Cancer

The assumption that cancer can be prevented by daily vitamin consumption has been proven false by research at Harvard Medical School in Boston.

The Women’s Antioxidant and Folic Acid Cardiovascular Study in co-operation with Brigham and Women’s Hospital followed 5,244 women with cardiovascular risks to see how folic acid, vitamin B6 and vitamin B12 affected rates of cancer.

Half of the women participating in the study, professionals over the age of 42, took the supplements daily while the other half took placebos. However, the results showed no significant difference in cancer rates between the two groups.

"A total of 379 women developed invasive cancer -- 187 in the active treatment group and 192 in the placebo group," said co-author Shumin Zhang. "Compared with placebo, women receiving the active treatment had similar risk of developing total invasive cancer, breast cancer, or any cancer death."

Since folic acid, vitamin B6 and vitamin B12 are key factors in DNA synthesis, it had been theorized that they could prevent cancer if taken regularly. Even though these supplements aren't proven to be preventative of cancer, they are still good for a multitude of other things your body needs -- so don't stop taking them.

Vitamin B6 is needed for protein metabolism, red blood cell metabolism, and proper functioning of the nervous and immune systems.

Vitamin B12 is needed for the normal functioning of the brain and nervous system, and for the formation of blood. It is normally involved in the metabolism of every cell of the body, affecting DNA synthesis and regulation, but also fatty acid synthesis and energy production. This is the stuff you take more of if you need more energy.

Folic Acid plays a large role in cell growth and development, as well as tissue formation.
A good, well-rounded multi-vitamin is recommended on a daily basis for general health maintenance, no matter what your age.

Source: http://www.acedmagazine.com/content/view/2040/40/