Louis Pasteur

[Yinzer]

What exactly do they do when they pasteurize our milk? And what is ULTRA pasteurized?

[amarillis]

Pasteurisation is the process of heating food for the purpose of killing harmful organisms such as bacteria, viruses, protozoa, moulds, and yeasts. The process was named after its inventor, French scientist Louis Pasteur. The first pasteurisation test was completed by Pasteur and Claude Bernard on April 20, 1862.

Unlike sterilisation, pasteurisation is not intended to kill all microorganisms in the food. Instead, pasteurisation aims to achieve a "log reduction" in the number of viable organisms, reducing their number so they are unlikely to cause disease (assuming the pasteurised product is refrigerated and consumed before its expiration date). Commercial scale sterilisation of food is not common, because it adversely affects the taste and quality of the product.

Pasteurisation is typically associated with milk. There are two widely used methods to pasteurise milk: high temperature/short time (HTST), and ultra-high temperature (UHT). HTST is by far the most common method. Milk simply labelled "pasteurised" is usually treated with the HTST method, whereas milk labelled "ultra-pasteurised" must be treated with the UHT method. HTST involves holding the milk at a temperature of 161.5 degrees F for at least 15 seconds. UHT involves holding the milk at a temperature of 280 degrees F for at least two seconds.

[BUNNY]

A few years the consultant microbiologist where I work did a study  about pasteurised milk and found active TB in some samples.He says ALWAYS drink UHT milk as it was fine.

[Yinzer]

Oh wow! Thanks for the in-depth answer amarillis. And BUNNY, I'll keep that in mind from now on, that's so gross!

[smudge]

I drink gallons of skimmed milk, but after reading these two informative answers, I shall be stocking up on UHT skimmed milk only, from now on. Thank you.

[Food student]

Actually the tuberculosis that you are referring to in pasteurized milk in not the tuberculosis that can cause the disease. Para-tuberculosis(a relative) traces can be found in pasteurised milk but it does not cause illness in humans. I'm studying food biotechnology in uni at the moment it gives some really practical knowledge. There is going to be some reconsideration about the possible increase in the official pasteurization temperature as it is listeria that you need to be careful about. Some strains of listeria can survive present temperatures though it is very rare to get listeria in milk; the risk would be made public if milk was that unsafe. I don't think that it is worth changing from UHT to pastuerized milk as the taste quality is absolutely abysmal, ultra heating can produce some odd, cooked flavours in it. UHT milk is more palatable is in baking and cooked products because the other flavours are cooked as well and they mask it.

[joecat]

I don't know what Ultra-pasteurized is, but pasteurization means heating the milk kill the bacteria so it will last longer.  Specific temperatures and durations are used to optimize the process.