This link help you
http://www.sciencedirect.com/science/article/pii/S0268005X09002185
Thermal (Heat) treatment results in the following chemical changes on milk proteins.
Maillard Browning ( non-enzymatic browning) reactions involving lactose and lysine in the protein. This gives rise to off-flavours, change in colour and loss of available lysine = Loss in nutritive value
Casein are very heat resistant. Heating above 100°C can cause decrease in casein micellar size due to increase in colloidal phosphate and dissociation of κ-casein from the micelle surface, also decrease in pH, which is caused by formation of organic acids from lactose degradation and precipitation of calcium phosphate,
Heat treatment causes whey protein denaturation ( irreversible), exposure of
hydrophobic residues and disulphide bonds may occur.
Mineral balance changes=. Calcium and phosphate becomes more insoluble and binds to the casein micellar structure.
These changes can be studied by PAGE, LC 2D methods
Thermal treatment can denature the milk protein casein. Milk protein reacts with sugar present in milk causing non enzymatic browning, called maillard reaction. some nutrient loss also occur like riboflavin, niacin which is heat and photo labile vitamin. Changes also take place in mineral content mainly calcium and phosphorus.
Multiple issues are related with heat treatment of milk. It depends on the type of protein and the range of heat treatment with the time of treatment.
In lab condition, it is also important to see the come-up time of steady-state temperature while doing the thermal treatments as it needs to be as quick as possible.
The following papers might be a good start to make a work plan-
http://www.sciencedirect.com/science/article/pii/S0958694697000496
https://www.intechopen.com/books/milk-protein/maillard-reaction-in-milk-effect-of-heat-treatment
https://www.intechopen.com/books/milk-protein/maillard-reaction-in-milk-effect-of-heat-treatment
protein denaturation happens, but not necessarily until it hits a certain temperature or as time will be extended. basically protein structure will be destroyed as well as other enzyme present in milk. The main protein in milk is casein, as temperature denaturates protein it can produce coagulation in milk. (the principle of clot on boiling test can explain this)
Follow this article
http://www.sciencedirect.com/science/article/pii/S0268005X09002185
Heat treatment denatures and coagulates whey proteins in the milk which will enhance the viscosity of the final product. Heating also promotes interactions between whey proteins and casein which also increase the viscosity of the product. .Alkaline Phosphatase, a natural enzyme in milk is also destroyed during the heating process
Dear Juma, The most important ingredients which effected in raw milk is the protein, vit A, minerals balance, but the level of effects were depended on temp. range and the time of heat treatment.
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