Cow's milk is a healthy dairy product that is really good to drink on a regular basis because it can provide the body with many benefits. If you are looking for cow's milk in supermarkets, you may notice there are two types that are most commonly found; UHT (Ultra High Temperature) milk and pasteurized milk.
What is the difference? Which one is better?
My name is Hamid, I am a food technologist with more than two decades of experience in food industry and I am going to elaborate on some important aspects of this subject that could be helpful for you to have a better choice!
The terms UHT and pasteurized are two ways of processing milk so that it can be consumed safely during the shelf-life.
Pasteurization is a method of destroying pathogenic bacteria which could cause different sicknesses like Q fever, Tuberculosis, Brucellosis, Salmonellosis, campylobacter enteritis, and so on by heating milk to a certain temperature in a short time. This method was invented in 1865 by a Frenchman named Pasteur.
The temperature of milk in pasteurization process is 72-85 degrees Celsius within 15-25 seconds. The goal is to reduce the number of microorganisms that can cause disease and slow down the growth of milk microbes. Even so, pasteurized milk must be drunk immediately, because it does not last long and needs to be stored in the refrigerator.
On the other hand, UHT is a method of sterilizing milk by heating it at a high temperature (between 135-145 degrees Celsius) for 3-5 seconds. The processing of milk at Ultra high temperature is considered capable of killing not only pathogenic bacteria but also all other microorganisms. It also deactivates all enzymes so that the milk can be sterilized and last a long time even though it is not stored in the refrigerator. It is necessary to mention that in order to have long lasting products, we should pack them aseptically. Aseptic packaging is a closed system thatno microorganism can contaminate the product unless the cap is opened.
The heating process carried out in both pasteurized and UHT milk cause them lose some vitamins specifically water-soluble vitamins like C, and B but it doesn’t make a significant change in the amount of fat-soluble vitamins such as D and E. However, in UHT milk, the heating process at high temperatures may damage more nutrients. In this process a small amount of protein and calcium is lost due to sedimentation in comparison to pasteurization. In addition, the soluble calcium in milk will turn into insoluble form, which may be difficult for the body to absorb.
Another important difference between Pasteurized and UHT milk is their Flavour. Generally, UHT milk has a cooked flavor but the intensity could be related to the type of technology and they all are not the same. Some part of the reaction of Millard which makes this cooked flavored could decrease the small amount of Lysin which is an important Amino acid of milk protein.
On the other hand, UHT milk has some advantages; the first one is the high quality milk due to the advanced technology and high-temperature process. it is indispensable to use the highest quality of raw milk so that we are certain about the quality of the final product.
Secondly, as UHT milk doesn’t need the cold chain, there is no concern about handling and distribution of these products after production. This could be vital, especially in those places in which there is no access to sufficient technology, electricity, and facilities.
Moreover, Whey proteins are sensitive to heat treatment and they get mostly unfold during UHT processing. it is important to mention that some researches show that denatured whey protein is easier to digest and then absorb in the body. This change can also decrease the allergenicity of whey proteins.
It is interesting to know that there is a product called ESL or extended shelf-life milk. The heat treatment of this product is similar to UHT with lower temperature but it doesn’t have the packaging process and specific materials like UHT. It terms of packaging, it is similar to the pasteurized milk. If we consider one week as the maximum shelf life of pasteurized milk, the shelf life of ESL milk is about 4 weeks in the refrigerator at 4 degrees centigrade and UHT milk has a shelf life of 4 to 6 months at the ambient temperature.
None of these three types have any preservatives and only the process is the reason for these shelf-lives.
To sum up, all these three types of milk are healthy and approved but my first choice is pasteurized one. The most important point is consuming 2-3 portions of any type of dairy products a day such as low fat or full fat, lactose-free, flavored or plain, fortified by vitamin D, Calcium and so on. It is totally up to you and there is no big difference between the types.
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