Dairy Industry
Plate heat exchanger for dairy is a crucial component of dairy processing, to guarantee that their dairy products meet industry requirements and are safe for human consumption. Liquid milk is a relatively stable fluid with few handling and processing difficulties. The majority of dairy businesses employ straightforward plate-type heat exchangers to carry out activities like pasteurization, sterilization, and other food processing as milk can be easily heated to the desired temperature.
Although handling liquid milk is simple, other dairy products including yogurt, butter, curds, and cheese all need to be processed and stored at different temperatures. Routine procedures may degrade their critical parameters if they are handled improperly. It is crucial that businesses that process dairy products choose a heat exchanger that is appropriate for the kind of product they are making.
HFM Plate Heat Exchanger in Dairy Industry
Contribution of networks to the globalization of the dairy industry, all the gamers are dragged to one giant checkerboard. Although the market share is expected up to thousands of billion by 2024, it is never easy to survive in the dynamic and complex marketplace arena.
HFM has been dedicated to hygiene plate heat exchangers for more than ten years. We provide highly efficient and economical solutions and plate heat exchangers for our dairy customers.
UHT & HTST
Pasteurization is a process of heating food or beverages to a specific temperature for a certain amount of time in order to kill harmful bacteria, viruses, and other microorganisms that may be present. This process was first developed by the French scientist Louis Pasteur in the 19th century as a way to prevent spoilage in wine and beer.
The basic principle of pasteurization is to heat the product to a temperature that is high enough to kill the microorganisms but low enough to avoid damaging the product itself. The exact temperature and time required for pasteurization depend on the type of product being processed and the specific microorganisms that are targeted.
There are several different methods of pasteurization, including Ultra High Temparature (UHT) and High Temperature Short Time (HTST).
Ultra-high temperature processing (UHT), also known as ultra-heat treatment or ultra-pasteurization, is a sterilization method used to heat food products to temperatures above 135°C (275°F) for 1 to 2 seconds in order to kill spores in milk and other microorganisms that may be present. While UHT is most commonly utilized in milk production, it is also applied to other food and beverage items such as fruit juices, cream, soy milk, yoghurt, wine, soups, honey, and stews.
It is important to note that the heat exposure of UHT can lead to Maillard browning and cause changes in the taste and aroma of dairy products. Therefore, an alternative to UHT is the HTST pasteurization (high temperature/short time) method, in which milk is heated to 72°C (162°F) for a minimum of 15 seconds.
When packaged in a sterile container that has not been opened, UHT milk can remain unrefrigerated for a shelf life of six to nine months. In comparison, HTST pasteurized milk has a shorter shelf life of about two weeks from the date of processing, or approximately one week from the point of being put on sale.
Technology in UHT
Overall, UHT processing is a complex and automated process that involves multiple stages of heating, cooling, homogenization, and aseptic packaging to produce safe, high-quality, and shelf-stable food products:
Heating:
Heating is a process that is used in food processing to increase the temperature of the product to a specific level required for processing, pasteurization, or sterilization.
In the context of ultra-high-temperature processing (UHT), heating is the first stage of the process where the liquid is pre-heated to a non-critical temperature (70-80°C for milk) before being rapidly heated to the required temperature.
Flash Cooling:
Flash cooling is the process of rapidly cooling a product after it has been heated to a high temperature. In the context of UHT processing, flash cooling is used after the product has been heated to the required temperature to prevent overcooking and to maintain the desired product characteristics.
Homogenization:
Homogenization is a mechanical process that is used to break down the fat globules in the product and distribute them evenly throughout the liquid. This process is particularly important for dairy products such as milk, as it helps to prevent the cream from separating out of the liquid. Homogenization is typically performed after the product has been heated and before it is packaged.
Aseptic packaging:
Aseptic packaging is a method of packaging food products that involve sterilizing the packaging materials and the product separately, and then filling and sealing the product in a sterile environment. This process helps to maintain the quality and freshness of the product for an extended period of time, without the need for refrigeration or other preservation methods.
Aseptic packaging is a critical stage in UHT processing as it ensures that the product is free from bacteria and other microorganisms that can cause spoilage.
Indirect Heating System
Direct heating and indirect heating are two different methods of pasteurization that can be used depending on the type of product and the desired outcome. Indirect heating, on the other hand, involves heating the product indirectly through a heat transfer surface, such as a heat exchanger.
In indirect heating systems, a solid heat exchanger, akin to those utilized in pasteurization, is employed to heat the product. However, at elevated temperatures, higher pressures must be applied to prevent boiling. Three types of exchangers are commonly employed:
- Plate Heat Exchanger
- Tubular Heat Exchanger
- Scraped-surface exchangers.
Presently, the plate heat exchanger is deemed the most efficient option. To further enhance efficiency, pressurized water or steam is utilized as the heating medium for the plate heat exchangers, along with a regeneration unit to enable the reuse of the medium, resulting in energy conservation.
HFM Plate Heat Exchanger for Dairy strictly adhere to the highest standards of quality and safety, ensuring all of our products meet the rigorous requirements of GRG, FDA, and SGS certifications.
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Plate Heat Exchanger for Milk Pasteurization Process Flow
Technical Requirements for Production Process
1. Acceptance of raw milk and classification
The quality of sterilized milk is determined by the quality of raw milk. Therefore, strict management and careful testing of raw milk are necessary to ensure its quality. Only raw milk that meets the specified standards should be used to produce sterilized milk.
2. Filtration or Purification
The primary purpose of milk filtration or purification is to remove dust and impurities from the milk.
3. Standardization
Milk standardization is essential to ensure that the milk contains the minimum amount of fat required. The requirements for milk standardization may differ from country to country, but typically, low-fat milk contains 0.5% fat, while ordinary milk contains 3% fat. In China, sterilized milk must contain 3.0% fat, and all non-standard milk must undergo standardization.
4. Homogenization
Homogenization is usually conducted at a homogenous temperature of 65 °C and a homogenization pressure of 10 to 20 MPa. A low homogenization temperature may lead to increased viscosity.
5. Sterilization
Pasteurized fresh milk is often contaminated with various microorganisms, 80% of which are lactic acid bacteria. Therefore, heat sterilization is the easiest and most effective method to eliminate potential hazards during milk production. Sterilization improves the stability of milk during storage and transportation, prevents rancidity, and inhibits the growth of microorganisms.
6. Cooling
Milk cooling is necessary to inhibit bacterial growth and prolong milk preservation. Typically, milk is cooled to about 4°C, while ultra-high temperature milk and sterilized milk may be cooled to below 20°C.
7. Filling
Milk filling aims to facilitate retail, prevent external impurities from contaminating the final product, avoid microbial re-contamination, preserve flavor, prevent absorption of external odors, and prevent loss of vitamins and other components. Filling containers are mainly packaged in glass bottles, vinyl plastic bottles, plastic bags, and plastic-coated paper bags.
Plate Heat Exchanger for Dairy Case Study – HTST Pasteurization
The steps to use the plate heat exchanger
1. Heat recovery section;
2. Sterilization section;
3. Cooling section;
The pre-cooled 5°C fresh milk is absorbed by heat in the heat recovery section, reaching about 65°C. It is homogenized by a homogenizer and then heated to 85°C for more than 15s.
Finally, it is cooled to 5°C with ice water, sent to the packaging workshop, and packed in bottles or soft plastic bags.
In the sterilization section, hot water is used as the heating medium, the cooling section uses ice water as the cooling medium, and the heat recovery section uses sterilized milk as the heat medium to fully utilize the heat of the hot milk to heat the cold milk. The heat recovery rate can be reached—85%~90 %.
Plate Heat Exchanger for Dairy Design Solution
Plate material: 304 or 316
Gasket: NBR
1. Heat recovery section: Both sides of the medium are milk
Hot side inlet temperature: 85 degrees or more
Cold side inlet temperature: 5 degrees outlet temperature 65 degrees
2. Sterilization section:
Cold side: preheated milk; temperature: inlet: 65 out 85 or more
Hot side: hot water 95 or more
3. Cooling section:
Cold side: milk that needs to be preheated and ice water
Hot side: hot milk that kills bacteria
Application of Plate Heat Exchanger for Dairy – Ice Cream Production
The plate heat exchanger, which incorporates representatives for ice cream, is extensively utilized in the food industry. The ice cream production process comprises various steps such as sterilization, cooling, mixing, filling, and packaging of the mixture.
Prior to homogenization, the temperature of the ice cream mixture must be meticulously controlled to range between 65℃ to 70℃ using the plate heat exchanger. Deviations from this range can lead to the condensation of fat or a foul odor. Subsequently, the plate heat exchanger is utilized for sterilization prior to transferring the material to the ageing tank, which brings the material to the required temperature for aging.
This process optimizes cost efficiency by combining heating and sterilization procedures. Due to the relatively viscous nature of ice cream material, Hofmann’s BNF series of plate heat exchangers with wide flow paths and high heat transfer efficiency presents an excellent choice for this heat transfer operation.
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