Ultra-high temperature processing, (less often) ultra-heat treatment (both abbreviated UHT), or ultra-pasteurization is the sterilization of food by heating it for an extremely short period, around 1–2 seconds, at a temperature exceeding 135°C (275°F), which is the temperature required to kill spores in milk.[1] The most common UHT product is milk, but the process is also used for fruit juices, cream, soy milk, yogurt, wine, soups, and stews.[1] UHT milk was invented in the 1960s, and became generally available for consumption in the 1970s.[2]
High heat during the UHT process can cause Maillard browning and change the taste and smell of dairy products.[3]
UHT milk has a typical shelf life of six to nine months, until opened. It can be contrasted with HTST pasteurization (high temperature/short time), in which the milk is heated to 72°C (161.6°F) for at least 15 seconds.
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UHT milk has seen large success in much of Europe, where across the continent as a whole 7 out of 10 Europeans drink it regularly.[6] In fact, in a hot country such as Spain, UHT is preferred due to high costs of refrigerated transportation and "inefficient cool cabinets".[7] Europe's largest manufacturer, Parmalat, had $6 billion of sales in 1999.[6] UHT is less popular in Northern Europe and Scandinavia, particularly in the United Kingdom, Ireland, Norway, Sweden and Denmark. It is also less popular in Greece, where fresh pasteurized milk is the most popular type of milk.
| Country | percent |
|---|---|
| Austria | 20.3 |
| Belgium | 96.7 |
| Croatia | 73[9] |
| Czech Republic | 71.4 |
| Denmark | 0.0 |
| Finland | 2.4 |
| France | 95.5 |
| Germany | 66.1 |
| Greece | 0.9 |
| Hungary | 35.1 |
| Ireland | 10.9 |
| Italy | 49.8 |
| Netherlands | 20.2 |
| Norway | 5.3 |
| Poland | 48.6 |
| Portugal | 92.9 |
| Slovakia | 35.5 |
| Spain | 95.7 |
| Sweden | 5.5 |
| Switzerland | 62.8 |
| Turkey | 53.1 |
| United Kingdom | 8.4 |
In June 1993, Parmalat introduced its UHT milk to the United States.[10] However in the North American market, consumers have been uneasy about consuming milk which is not delivered under refrigeration, and have been much more reluctant to buy it. To combat this, Parmalat is developing UHT milk in old-fashioned containers. Many milk products in North American foods are made using UHT milk, such as McDonalds McFlurries. UHT milk is also used on airplanes.
UHT milk is sold on American military bases in Puerto Rico.[11] and Korea due to limited availability of milk supplies and refrigeration.
UHT milk gained popularity in Puerto Rico as an alternative to pasteurized milk due to environmental factors. For example, power outages after a hurricane can last up to 2 weeks, during which time regular pasteurized milk would spoil from lack of refrigeration.
In 2008, the UK government proposed a 90% UHT milk production target by 2020[12] which they believed would significantly cut the need for refrigeration, and thus benefit the environment by reducing green house emissions.[13] However the milk industry opposed this, and the proposition was quickly abandoned.
In Thailand, environmental concerns relate to UHT milk cartons. Tetra Pak (Thai) Ltd. is due to "establish Southeast Asia's first recycling plant for used UHT drink containers".[14]