Ultra-high temperature processing ( UHT ), ultra-hot treatment , or ultra-pasteurization is a food processing technology which disinfect liquid food, especially milk, by heating it above 135 ° C (275 ° F) - the temperature required to kill spores in milk - for 1 to 2 seconds. UHT is most often used in milk production, but this process is also used for fruit juice, cream, soy milk, yogurt, wine, soup, honey, and stews. UHT milk was first developed in 1960 and became available for consumption in the 1970s.
The heat used during the UHT process can cause Maillard to change color and change the taste and smell of dairy products. The alternative process is HTST pasteurization (high temperature/short time), in which the milk is heated to 72 ° C (162 ° F) for at least 15 seconds.
UHT milk packaged in sterile containers, if left unopened, has an unfiltered shelf life of six to nine months. In contrast, HTST pasteurized milk has a shelf life of about two weeks from processing, or about a week since it was sold.
Video Ultra-high-temperature processing
Histori
The most common technique applied to provide safe and stable milk is heat treatment. The first system involving indirect heating with continuous flow (125 Â ° C for 6 minutes) was produced in 1893. In 1912, the direct heating method, the direct flow of vapor mixing with milk at a temperature of 130 to 140 Â ° C was patented. However, without the commercially available aseptic packaging system for packing and storing products, such technology is not very useful, and further development stalled until the 1950s. In 1953, APV pioneered steam injection technology, which involves direct injection of steam through a specially designed nozzle that instantly increases product temperature, under the Uperiser brand name; milk is packed in sterile cans. In 1960, APV launched its first commercial steam infusion system under the brand name Palarisator.
In Sweden, Tetra Pak launched a carton tetrahedral carton in 1952. They made a commercial breakthrough in 1960, after technological advances, incorporating carton assembly and aseptic packaging technology, followed by international expansion. In aseptic processes, products and packets are sterilized separately and then combined and sealed in a sterile atmosphere, in contrast to canning, where products and packets are first combined and then sterilized.
Maps Ultra-high-temperature processing
Technology
Extremely high temperature processing is performed in complex production plants, which perform several stages of processing and packing food automatically and consecutively:
- Heating
- Flash cooling
- Homogenization
- Aseptic packaging
In the heating step, the treated liquor is first heated to a non-critical temperature (70-80 ° C for milk), and then heated rapidly to the temperature required by the process. There are two types of heating technology: directly , where the product is placed in direct contact with hot steam, and indirectly , where the product and heating media remain separate. by the contact surface of the equipment. The main purpose of the design, both from product quality and from an efficiency point of view, is to maintain a high product temperature for the shortest period, and to ensure that the temperature is distributed evenly throughout.
Direct heating system
The direct system has the advantage that the product is held at high temperatures for a shorter period of time, thereby reducing thermal damage to sensitive products such as milk. There are two groups of direct systems:
- Injection-based, where high-pressure steam is injected into the liquid. This allows quick heating and cooling, but is only suitable for some products. When the product comes in contact with the hot nozzle, there is a possibility of local heat.
- Infusion-based, where liquid is pumped through the nozzle into a room with high-pressure steam at relatively low concentrations, provides a large surface contact area. This method achieves instantaneous warming and cooling and temperature equalization, avoiding excessive heat. It is suitable for low and high viscosity liquids.
Indirect heating system
In an indirect system, the product is heated by a solid heat exchanger similar to that used for pasteurization. However, since higher temperatures are applied, it is necessary to use a higher pressure to prevent boiling. There are three types of exchangers used:
- Plate plate,
- Tubular exchanger
- Scalp surface exchanger.
For higher efficiency, pressurized water or steam is used as a medium for heating the exchanger itself, accompanied by a regeneration unit that enables media reuse and energy savings.
Flash cooling
Once heated, the hot product is passed to the retaining tube and then to the vacuum chamber, where it suddenly loses temperature and evaporates. The process, referred to as flash cooling, reduces the risk of thermal damage, removes any or all of the excess water obtained by contact with the vapor, and removes some of the volatile compounds that negatively affect the product. quality. The cooling rate and quantity of discharged water is determined by the vacuum level, which should be carefully calibrated.
Homogenization
Homogenization is part of a special process for milk. Homogenization is a mechanical treatment that results in a reduction in size, and an increase in the total number and surface area, fatty clumps in milk. That, in turn, reduces the tendency of milk to form cream on the surface and on contact with the container, improves its stability, and makes it more suitable for consumers.
Aseptic packaging
Aseptic packaging refers to a technique in which pre-sterilized milk is aseptically packed in sterile packages and tightly closed to extend shelf life even under ambient conditions.
Worldwide use
UHT milk has seen great success in most of Europe, where across the continent as a whole 7 out of 10 Europeans drink it regularly. In fact, in a hot country like Spain, UHT milk is preferred because of the high cost of refrigerated transport and "inefficient refrigerators". UHT is less popular in Northern Europe and Scandinavia, particularly in Denmark, Finland, Norway, Sweden, the UK, and Ireland. It is also less popular in Greece, where fresh pasteurized milk is the most popular type of milk. This may be largely due to differential rates of lactose intolerance in Europe; high-tolerance populations can drink large amounts of milk, making palatability of lower UHT milk more visible.
In June 1993, Parmalat introduced UHT milk to the United States. In the American market, consumers feel uncomfortable consuming milk that is not shipped in the refrigerator, and are reluctant to buy it. To eradicate this, Parmalat sells its UHT milk in an old container, no need to be sold from the refrigerator aisle. UHT milk is also used for many dairy products.
UHT milk is sold at American military bases in Puerto Rico and Korea due to limited availability of milk supply and refrigeration.
UHT milk is gaining popularity in Puerto Rico as an alternative to pasteurized milk due to environmental factors. For example, a power outage after a hurricane can last up to 2 weeks, during which time pasteurized milk will be damaged by lack of cooling.
In 2008 the UK government proposed a 90% UHT milk production target by 2020 which they believe will significantly reduce the need for cooling, and thus benefit the environment by reducing greenhouse emissions. But the dairy industry is against this, and the proposition is abandoned.
The nutritional effect
- Calories
- UHT milk contains the same amount of calories as pasteurized milk.
- Calcium
- UHT milk and pasteurization contain the same amount of calcium.
- Protein
- The protein structure of UHT milk differs from pasteurized milk, which prevents it from splitting in cheese making.
- Folate
- UHT milk contains 1? g folate per 100 g, while the pasteurized milk contains 9? g.
- Some loss of Vitamin B 12 , vitamin C and thiamin can occur in UHT milk.
See also
- Aseptic processing
- Food preservation
- Food storage
- Food packaging
- Food engineering
- Pasteurization
References
External links
- Milk in the Box. From: Interesting Things Today
Source of the article : Wikipedia
0 Comments