Why must most milk sold in the US be refrigerated at all times while evaporated canned milk and milk in cardboard containers sold in Europe do not need to be refrigerated until they are opened?
Milk sold in the US needs to be refrigerated at all times because it is pasteurized while the milk sold in Europe does not need refrigeration until it is opened because it is UHT milk. The main difference is the way the milk is sterilized. While the milk in the US is pasteurized, the milk in Europe is UHT.
The milk in the US is pasteurized and this implies that the milk is taken through a process of heating the milk for up to 75 degrees centigrade for about 15 to 20 minutes. Pasteurization is done to kill the pathogenic bacteria hence protect the consumer from harm. In addition, pasteurization is done to extend the shelf file of the milk by killing the milk souring bacteria and also to ensure that the quality of milk is kept for some days before the consumer can use it (Ozer & Akdemir-Evrendilek, 2014).
However, this milk has to be refrigerated throughout from the time the milk is transported for distribution to the time it is sold in stores. Pasteurized milk can spoil if it is not properly stored or when not refrigerated. The bacteria that cause the spoilage are often not harmful even though the consumer might get offended for purchasing spoilt milk. The ideal temperatures for the storage of pasteurized milk are 35 to 38 degrees Fahrenheit and this is how the milk in US is stored. Once refrigerated, the pasteurized milk can remain fresh for up to five days. However, consumers are advised to consume any opened pasteurized milk as soon as possible to avoid spoilage.
Ultra Heated Milk or Ultra Pasteurized milk is sterilized by heating the milk for 280 degrees Fahrenheit or 130 degrees Celsius for 2 seconds. This high temperature helps in killing all the bacteria in milk. UHT milk is also stored in aseptic containers or boxes that are sterile and help keep the milk fresher for longer. UHT treatment mostly occurs in a closed environment and this process helps to prevent contamination and maintain the nutrient content of the milk. The aseptic packaging helps to extend the shelf like of the milk and any UHT milk stored in aseptic containers can stay fresh for up to 5 months. The milk sold in Europe in UHT that is stored in aseptic containers and cans that do not need refrigeration. However, once opened the UHT needs to be refrigerated as opening them exposes them to airborne contamination (Ozer & Akdemir-Evrendilek, 2014).
Both UHT and pasteurized milk can be stored in aseptic containers to help extend their shelf like. Pasteurized milk that is stored in aseptic containers can remain fresh for up to two weeks. The packaging of these containers is meant to prevent air and moisture from contaminating the milk. Besides, aseptic packaging does not require additive and preservatives for the milk and this preserves the flavour and the nutrient content of the milk.
While there is a notion that UHT milk is not good for consumption as it has preservatives, this is not true as the freshness and quality of the milk only relies on the heating process and the aseptic packaging. Both pasteurization and UHT treatment are good forms of sterilizing milk and no additional preservatives are needed to maintain the quality of milk. Aseptic packaging is however the best containers to store the two types of milk.