What Happens If We Keep Heating Milk?
Heating of milk :
Heating of milk can be done to prevent the milk from spoiling. Heating of milk leads to destroying the microbial growth and preventing its enzymatic activities which subtle the growth and kills the bacteria present in the milk.
However, the heating of cow's fresh milk is said to be done up to the milk started taking its boil as the milk after 4 to 5 hours of milking started showing the continuous growth of pathogenic microbes.
But when you ask for boiling the packed milk/ pasteurized milk. It is of no use. As the packed milk is pasteurized well to prevent its spoilage, so, it isn't suggested to boil the packaged milk, however, you can heat it to lukewarm according to your taste before consuming as the taste buds of each person have their taste.
Heating the milk should be done in a particular period and with the proper way at the proper flame. Over or less heating should be completely avoided.
How and when to heat the raw milk?
It is often said that "Always boil the milk before drinking it".
Ever thought how true it is?
Not 100% but partially it is.
The statement should be more clear, we can say it as " Always boil cow's milk under 4-5 hours of milking".
Always give your milk a low flame boil, avoid using high temperature for boiling up your milk.
The high flame boil shouldn't be given as protein contains a good percentage of protein in it. And as the protein starts losing its chemical bonding and starts denaturing so the nutritional value of the protein is thus decreased to some extent.
Always use the vessel larger than your milk level so it would come after raising its level while boiling. As milk started forming foam and creating an air-filled balloon-like raise during taking boil.
Don't give your milk so prolonged and repetitive heating as it starts thickening as its water content starts evaporation.
Heating so many times milk decreases its nutritional content.
Give your milk uniform heating so that the milk should be properly heated and the germs should be completely killed.
Heating raw milk is always a good idea as it increases the shelf life of the fresh milk, but it's never a good idea for the pasteurized milk.
You can use pasteurized or packaged milk directly for eating purposes if it is stored at a low temperature in a chilled condition, if not as if the pasteurized milk is stored at room temperature it should also need to be boiled.
You can store the heated milk in the refrigerator for further use.
Difference between heating up and boiling up the milk?
Do we heat the milk or boil the milk?
Let us understand the difference and the impact of heating and boiling the milk first!
Heating and boiling of the milk have different impacts on the raw fresh milk. If you just heat the milk and leave the milk it will not kill up the whole microbes in it. They just partially degenerate the growth of the pathogenic microbes. And when you boil the milk it completely makes your milk microbes free and makes it safe for drinking.
When you are using pasteurized milk it isn't necessary to boil the milk soon after buying. You can store it in your receiver and can directly use it for your eating purposes.
You can heat the milk before having it, as every person has its specific taste, everyone wants to consume milk in their style. Some want to have lukewarm plain milk, some add some taste enhancer product like bournvita, complain, boost, to it. Some like to have it chilled.
So as per your convenience, you can heat both pasteurized and raw milk according to your use and taste, but over and repetitive heating can diminish the nutritional value so if not needed, do not heat milk repeatedly and avoid overheating too.
Three different ways to heat milk :
1) Stove or induction heating:
The most preferred way of heating the milk is stovetop heating or induction heating. People generally use this heating method in their daily use for heating the milk. For stove or induction heating, it would be great and safe to use a thick and large pan. The vessel should be a few inches empty after pouring the milk into it. As the milk boils soundlessly, and when it boils it starts raising its level.
Always set a low to medium flame for heating the milk, as it prevents denaturation of milk's protein. Stir it in between for the homogenized and even heating, it is better to use a long-handled spoon which can prevent milk from overflowing.
2) Microwave heating:
Use a microwave container for heating and boiling the milk, set the microwave at medium-high, and keep stirring it every 15 seconds at 70% power.
When you start seeing the rise of steam from your milk you can take it off for your use.
250ml of milk might take 2-3 minutes for its proper heating.
3) Double-boiler heating:
Double heating boiling of the milk is not so preferred type of boiling, as it involves some risk in the process.
For this double heating boil as the name indicates, two vessels are used for boiling up the milk, it can be said as the indirect heating of the milk.
A large vessel is taken whether of steel or any aluminum or copper metal, then water poured half to the vessel as the flame should be kept on. Another heatproof vessel is taken and is placed over the water-filled vessel it shouldn't touch the water level and there must be a distance of 1 inch in between the water level and the second vessel.
Turn off the flame once the milk is boiled and it can be stored in the refrigerator or can be used if you want to.
What happens when you overheat the milk:
It is well known that milk has up to 89-85% water content in it. So it's pretty simple that when you heat the milk the water content will casually evaporate while heating and when you keep on heating it will evaporate all over its water content and will leave with the solid residue.
The solid concentrated milk is known as " Mawa " "khoya" or " khoa". This concentrated solid milk is used for preparing different kinds of sweets like Gulab-jamun, Gajar halwa, Barfi, etc.
This concentrate is rich in phospholipid concentration and is sweetish in taste and creamy in texture. It enhances the tastes of any milk item.
If you continue heating the milk after its water content is completely evaporated, the non-enzymatic browning reaction will start taking place.
This will cause browning and burning of the milk which leads to the smell, color, and taste of the mawa. It starts smelling bad and tasting bitter and its color is changed from yellowish to caramel to even blackish.
Things should be taken care of while heating the milk:
Always use a thick pan while heating milk as when it starts boiling and its consistency begins thickening it starts being sticky from the bottom.
Always use bigger vessels to boil the milk. Never neck fill any vessel with milk for boiling purposes.
Stir regularly while boiling after every 15 seconds for its even heating.
Put a spoon (long-handled) dipped in the milk while boiling as it will or even your milk from overflowing.
Always use low to medium flame for boiling up the milk as it prevents denaturation of protein's milk.
Don't overheat the milk, it will result in lowering the nutritional value of the milk.
Avoid repetitive heating of milk. It can also decrease the nutritional content.
Always use fresh vessels for boiling the milk, as the used vessel may lead to the spoiling of milk quicker.
Do not take more than 25-30 minutes for boiling up 1 liter of milk.
Refrigerate the milk and store it for further use.