UHT Milk FAQ
Here we have gathered some of the most frequently asked questions about Ultra-High Temperature (UHT) Milk. We hope that you will find all the answers you might have when it comes to UHT Milk.
- What is UHT milk and how is it different from “fresh milk” and raw milk?
UHT milk is milk that has been processed at ultra high temperature (UHT). The sterilisation is made through rapid heating of milk to a temperature of at least 135°C, keeping it there for a few seconds, and then quickly cooling it down to ambient temperature. Such treatment results in that all microorganisms present in the raw milk are killed. When packaged into aseptic containers, UHT milk has a shelf life of many months and doesn’t need to be refrigerated until the package is opened. The shelf life of UHT milk is not limited by growth of microorganisms but instead by physical, chemical and enzymatic changes in the milk, such as browning reactions, cream separation, sediment or gel formation. “Fresh milk” is often used by consumers to describe milk that is distributed under chilled conditions. This usually refers to pasteurized milk, which means the milk that has been heated at 72-74°C for 15-20 seconds. Pasteurization kills all pathogenic (disease causing) microorganisms in the raw milk. To limit the growth of the remaining spoilage micro - organisms, pasteurized milk needs to be kept under chilled conditions throughout the distribution and storage. The shelf life of pasteurized milk depends on the initial load of microorganisms as well as storage temperature but is normally around 7 days. Raw milk refers to the milk produced by cows (or other animals) without processing. Drinking raw milk can cause serious diseases, as it can harbour dangerous microorganisms. According to the Food and Drug Administration (FDA), between 1993 and 2006 more than 1500 people in the United States became sick from drinking raw milk or eating cheese made from raw milk. For this reason, in many countries, all milk products sold in retail outlets must be pasteurized or UHT treated. In some markets, consumers buy raw milk and boil it at home. This makes the milk safe to drink but it is hard to control the process to maintain the quality.
- How long has UHT technology existed?
The birth of sterilised treatment as a means of preserving food began in France in the early 1800s. The food was filled in tin-coated steel containers which were placed in pressurised chambers, (auto - claves), in which they were heated to 110-125°C for 30-40 minutes. This process is called “in container sterilization”. In the late 1950’s, building on this earlier food conservation technology, Tetra Pak Processing Systems (Alfa Laval at the time) pioneered its own continuous UHT process. By using higher temperatures and shorter times it achieved the same effect in killing micro - organisms, while being much gentler towards changes to taste and colour of the milk. Together with Tetra Pak’s innovation of the aseptic package, this kick-started the growth of the UHT milk segment.
- Are there any preservatives used in UHT milk?
The ultra-high heat treatment used in the production of UHT milk kills all microorganisms. The milk is then packed in an aseptic package that protects it from entrance of any microorganisms, making it safe for months without need of refrigeration. There is simply no need to add preservatives into a UHT treated product, as there are no microorganisms growing. Aseptic containers also protect the product from air and light, thereby protecting the product quality.