Now the shelf life of milk drinks can be achieved by some technical means, such as sterilization, ultra-pasteurization, purification, microfiltration and so on.
A key difference between these ESL technologies is that some technologies, such as sterilization or purification, aim to sterilize dairy products so that they can be stored and transported at room temperature; Other technologies, such as ultra pasteurization and microfiltration, are used to refrigerate dairy products.
Sterilization treatment
Sterilized dairy products are obtained by rapidly heating at high temperature, then rapidly cooling to normal temperature, and pouring into aseptic packaging in an aseptic environment. Containers for aseptic packaging usually include aluminum cans, highly sealed bags and multilayer aluminum foil boxes.
Recently, an octagonal box with aluminum foil has become popular. By the end of 2002, high density polyethylene (HDPE) plastic bottles may be approved by FDA as aseptic packaging for low acidity products (such as milk drinks). These two kinds of aseptic packaging are well received in the market.
When Horizon Organic Dairy Company decided to take the independent packaging milk production line, the company hoped that the packaging would have its own characteristics in appearance, specifications, shelf life and recycling environmental protection performance. The company uses 8 oz, 8-sided aluminum foil box with straw, which is suitable for children and adults. The octagonal box is easy to grasp, especially suitable for children's small hands.
It is this easy-to-handle and stable shelf life that enables packaging suppliers to produce a packaging version with the capacity of 1 1 ounce, which looks like a conservative aluminum can package. Bravo Food International Company, with the help of Jasper Products Company, launched this kind of packaged flavored milk -Looney Tunes? 0? 3。 This packaged milk beverage can be transported to any aluminum canned beverage sales point, including retail stores, vending machines and supermarket shelves.
Jasper is Tetra Pak's partner in the sterilization and packaging system of metal foil boxes and sterile plastic bottles.
In many countries (including Canada), it has been possible to sterilize the process of pouring milk drinks into plastic bottles, but it is impossible to do so in the United States in the near future due to FDA regulations. In fact, the only low-acidity aseptic plastic bottle packaging system in the United States is Columbus, owned by Abbott Laboratories, which is used for infant formula and nutritious drinks. It is necessary to make some changes now.
Asep-Tech USA, LLC is an organization that tests the shelf life of milk drinks (including other drinks and foods) developed by the company. Asep-Tech is waiting for the approval of the US Food and Drug Administration for its aseptic packaging equipment for high-density polyethylene plastic bottles. Once approved, the company will register the factory as a cannery established by the federal government, which will pave the way for American processing plants to gain the same status and provide plastic bottles of milk drinks with stable shelf life for American supermarkets.
Dean Foods hopes to become the first aseptic liquid milk manufacturer in the United States. Recently, it used high-density polyethylene plastic bottles to inject ultra-pasteurized Hershey milk and Jakada coffee from folger. The shelf life of cold storage can reach 90 days. Once the FDA agrees, the company will sterilize it, and it is possible to obtain a shelf life of 180 days at room temperature. In order to achieve sterility, the processing factory needs to make some minor changes to the packaging process, including disinfecting the metal cover with hydrogen peroxide spray.
Jaspe also hopes to become a leader in the commercial production of aseptic plastic bottle packaging for milk drinks in the United States. Obviously, aseptic plastic bottle packaging of milk drinks is a new opportunity in commercial competition.
Sandwich substances in plastic bottles should also be considered during sterilization. Using HDPE as sandwich material is better and more expensive than using PET, but some excellent sandwich materials of PET are being developed. At present, it may be feasible to use PET.
Pay attention to the label during sterilization. It has been found that the solvent of dyes used on some labels will penetrate into the pores of HDPE bottles, and after storage time (usually more than 90 days), the products will have the smell of solvents.
Ultra pasteurization treatment
Ultra-pasteurized products are produced under slightly looser conditions than sterilization, in which heat treatment and clean packaging treatment are still the key steps. This processed milk beverage is usually packed in milk cardboard printed with cartoon patterns, or in HDPE or PET bottles. In order to avoid the photosynthesis of beverages, PET bottles are much brighter than opaque HDPE bottles, so it is necessary to dye or fully package the whole label. There is a small window on the label so that consumers can see the products inside.
The mouth of the ultra-pasteurized bottle has a sealed metal foil cover, which can avoid pollution and keep the product for 90 days.
Some processors want to get a longer shelf life than the standard 14 days, but are unwilling to pasteurize their milk, so they can choose a compromise treatment method, such as higher temperature/shorter time. Short heat treatment time can reduce the loss of milk at sterilization and ultra-pasteurization temperatures. The shelf life of the treated product can reach 30 days. This is how milk in America is treated.
purification treatment
Purified products should be packed in containers, generally speaking, containers have aluminum cans or multi-layer metal foil bags. At present, containers are heated at extreme temperatures to ensure the sterility of products. Although bacteria can be successfully eliminated, purification may change the nutritional and flavor characteristics of milk drinks.
Researchers are exploring the potential of PET bottles in purification treatment, which can represent the shelf stability of PET. You can press a lid on the purified PET bottle mouth through the pressure production line, not necessarily metal.
Microfiltration treatment
Microfiltration is a non-heat treatment step before pasteurization, which can extend the shelf life of milk to 45 days.
Microfiltration treatment is to filter out harmful bacteria in milk with ceramic filter membrane, thus prolonging the shelf life. Because it is not heat treatment, milk is less damaged by heat.
Other techniques to extend the shelf life (ESL) of milk;
Gas treatment method
Mixing natural gas such as carbon dioxide in packaging can prolong the shelf life of refrigerated liquid milk by inhibiting or slowing down the growth of bacteria.
High pressure treatment
High pressure treatment can promote the combination of non-* * valence hydrogen, leading to protein denaturation, thus causing bacterial inactivation. This technology must be further studied before it is applied to milk treatment.
Pulsed electrotherapy
Now we can use intense pulsed electricity to inactivate microbial cells, effectively preserve food, and generate almost no heat. More research is needed before commercial application.
Irradiation treatment
In radiation treatment, food exposed to gamma rays can kill pathogenic bacteria. Radiation treatment has been approved for milk treatment.
Temperature monitoring equipment
Food companies have widely used temperature fluctuation monitors on containers, but until now, they have not been used in milk and beverage production.
These devices are some obvious color-changing stripes applied to the outside of the package. When the temperature exceeds the preset range, the colors of these stripes begin to change. This monitor can help consumers buy refrigerated ESL milk during the shelf life. In the future, this technology will be widely used in the milk industry.