I audited operational processes of one of the famous brands in Pakistan in 2007.
First of all, we have to understand the terms in use in milk industry:
Raw Milk: Raw milk is the unprocessed milk that has not undergone any process of heat treatment or homogenization. Milk in its raw form is usable only for a few hours and naturally throws the cream on top (without boiling). If you leave this milk for a few hours, the top portion of this milk is more creamy and butter can be obtained from it. To drink it,
Pasteurization: Heating the milk to a certain temperature and then quickly cooling it down to eliminate bacteria.
There are three temperatures used to pasteurize milk
1 - 145 Degrees F for 30 minutes (Milk is usable for a couple of days if hygienically packed)
2 - 165 Degrees F for 15 to 20 seconds (Milk is usable for 2-3 weeks if hygienically packed)
3 - 280 Degrees F for 02 seconds (Ultra High Temperature -UHT treatment, that keeps the milk usable for months if hygienically packed properly, mostly in tetrapak packaging)
Boiling Point of Milk: 212.6 Degree F
Homogenization: It's the process that leads to evenly mixing fat molecules by breaking them into smaller particles so that the cream doesn't gather on top and is evenly distributed in the whole volume. Homogenization makes it impossible to get cream out of the milk even after boiling.
Clotted Cream: The cream that clots on top of the raw milk after boiling.
Skimmed Milk: The milk left after taking the cream out of it.
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At the time when I audited that company, most of the companies in this industry didn't have their own farms. They had contracts with local farmers who supplied the milk to them. The formula of price depended on the specific gravity of milk (that tells how creamy is the milk and how much water has been mixed in it). So, companies knew that what's the specific gravity of milk containing 3% fat, 1.5% fat, 0.5% fat and 4% fat. The standard they had set at that time was that if a farmer brings milk having specific gravity of 3% fat, they gave them full amount, the lesser the specific gravity, the lesser amount was paid to the farmers (which means that either they had mixed water in it, or took out the top portion of the milk themselves to make butter and ghee). The milk with less specific gravity was subjected to evaporation until the required thickness is not obtained.. so naturally the volume would reduce and hence less payments to the farmers.
After getting the standard thickness, the company used to homogenize and pasteurize the milk at UHT (much more than the boiling point) to kill the bacteria and pack it immediately so that bacteria in the environment do not enter the milk before it is packed.. This way, milk is drinkable for a longer period of time if remains packed properly.
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Now interesting facts:
The COO told me that farmers have the ways to take out the cream and mix certain chemicals in the milk to make the thickness acceptable for full payment. Most of the companies (including the one that I audited) didn't have any process to identify any chemicals in the milk supplied by the farmers.
UHT treatment changes the taste of the milk to somewhat burnt. Anyone who has knowledge of how the raw milk (or even boiled raw milk) tastes, he can immediately tell the difference in taste of unnaturally burnt milk. This UHT treated milk is less healthy (according to the company's COO too, although he wanted to say that it is not healthy).
It is not a guarantee that UHT treated milk in tetrapak packaging doesn't contain harmful hormones and chemicals, because most companies do not have means to validate this information (I don't know about now, but 10-12 years back, this was the case and that's why when SC tested the milk, most of the brands were found to supply harmful milk.
Heating the milk to 165 degrees F kills 99% bacteria in the milk.. In our homes, we boil it, which takes the temperature to 212.4 degree F. It's still not burnt, because boiling point doesn't allow burning of the ingredients in the milk.. If 165 degree F kills almost all the harmful bacteria, what about boiling the raw milk which also kills 99-100 percent bacteria?
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Conclusion:
Unless we know that the milk company doesn't produce milk in its own farms, the packaged milk can easily be considered harmful.
Milk companies which also produce butter and cream, it can be assumed that they are also involved in artificial thickening of milk, because otherwise they can't get enough cream to sell separately or convert into butter. Homogenization makes it impossible to find out whether cream has been extracted out of the milk, because there's no cream clotted at all.. so we can never know whether the thickness of the packaged milk is due to cream or some other compound/ chemical.
The best milk is raw (consumed within minutes of extraction), or heated till 165 degree F only, if left for a few hours. Boiling is not necessary, but it does give clotted cream.
@Mentee @War Thunder @Maxpane @newb3e @BHarwana @fitpOsitive