Development and Application of Aseptic Packaging Technology for Food

[China Packaging Network News] Food aseptic packaging technology is food in the aseptic state, the sterilization of food into sterile packaging containers, sealed packaging. Because this kind of packaging does not add preservatives, the nutrition and flavor of foods are not destroyed, and they can be stored at room temperature for a long time, which has become a trend of modern food packaging. This article will introduce aseptically packaged foods, aseptic packaging containers, sterile packaging equipment and the environment.

It is well known that foods need to be packaged from the production of raw materials to the hands of consumers. Traditional packaging methods make the nutrition and flavor of foods damaged to a certain extent, and foods are aseptically packaged. Without adding any preservatives, foods can be kept at room temperature for a long time without affecting the nutrition of foods. And flavor, this will inevitably become the trend of food packaging.

Aseptic food packaging refers to products that have been sterilized and have obtained commercial sterility. They are enclosed in sterilized containers and filled in a sterile environment. After filling, the containers are sealed to prevent re-infection, so as not to increase Preservatives, packaging methods that give longer shelf life without refrigerated conditions. The application of aseptic packaging in food began in 1913 when Danish Daikins made aseptic filling of milk, and in 1917 the American man Klein acquired the world’s first patent for the sterile preservation of food, in the late 1970s. In the future, aseptic packaging technology for food has emerged widely.

As people pursue natural green health foods, aseptic packaging technology has begun to develop rapidly in food. China's food industry has gradually introduced aseptic packaging technology after its reform and opening up. Compared with foreign countries, there is still a gap in the level of self-development and development. Therefore, China must understand the development status of world aseptic packaging technology in order to improve its own technology.

Aseptic packaging is different from traditional packaging in that it uses packaging containers made of materials that are resistant to bacteria and have good barrier properties. The food and packaging containers are sterilized separately, in addition to better sterilization of food and container packaging. Microorganisms carried inside can also prevent food and packaging containers from reacting at the same time to sterilize them. After sterilization, they can use modern mechanical means to pack aseptic foods in aseptic packaging containers, seal the packaging, and ensure the food after packaging. Being in a vacuum state, you can avoid intrusion of moist air, sunlight, and microorganisms.

Therefore, the aseptically packaged food may not need to be added with a preservative, and the color, flavor and nutrient content of the food may not be destroyed, and it may be stored at room temperature for a long time. Food aseptic packaging technology has many advantages over traditional packaging technologies, and it has been widely used in the production of various types of beverages, alcoholic beverages, dairy products, condiments and canned foods. The aseptic packaging technology will be discussed below from aseptically packaged foods, aseptic packaging containers, sterile packaging equipment, and the environment.

Sterile packaged foods refer to foods that have not been sterilized by reheating but have been sterilized in sterile packaging. To obtain aseptically packaged foods, the foods must be sterilized and cooled prior to packaging to ensure sterility. There are many methods of food sterilization, including heat sterilization such as: low temperature sterilization, ultra-high temperature instantaneous sterilization, radiation sterilization such as: ultraviolet sterilization, microwave sterilization, chemical sterilization and filter sterilization. Each sterilization method has its own advantages and disadvantages. In the process of food sterilization, it can be used alone, or it can be combined with two or more sterilization methods to improve the sterilization effect. Because the same sterilization method has different effects on foods with different properties, different sterilization methods can be selected according to the characteristics of the food, whether it is resistant to high temperatures, whether the color is required or not. Heating is currently the most common method of sterilization, so pasteurization (hyperthermia) and ultra-high temperature (UHT) are described here.

Low-temperature sterilization refers to the method of heat treatment with relatively low temperature. The food to be sterilized is sterilized at a sterilization temperature of 61-63° C. for 30 minutes, or sterilized at a temperature of 72-75° C. for 10-15 minutes. This sterilization method can be used directly on foods, or it can be packaged and immersed in hot water. The low-temperature sterilized food has the characteristics of long heating time, discontinuous production process, large loss of nutrient composition and flavor, and unsatisfactory sterilization effect.

The ultra-high temperature instantaneous sterilization is to sterilize foods that need to be sterilized at 125-150° C. for 2-8 seconds, cooled to about 20° C., and sealed in the aseptic zone so that the processed foods can meet the aseptic requirements. Sterilization process. For example, UHT sterilization parameters of milk are sterilized at high temperatures for 3~4s. Instantaneous high-temperature sterilization Because the food is only sterilized at high temperature and the food is heated for a short period of time, the packaging material is not sterilized at high temperatures, so the packaging material may not be tolerant to high temperatures, and the filling, nutrient composition and flavoring are not performed until the sterilization is completed. The loss is small and it is widely used in food sterilization.

Aseptic packaging container

Due to the characteristics of aseptic packaging, in the packaging process, the characteristics of the packaging material must first be considered.

(A) Characteristics of Aseptic Packaging Materials

High strength

In the process of sales, foods need to be handled, transported, placed, stored, etc. In the process, they are vulnerable to external pressure such as pressure, vibration, impact, etc. If the packaging materials are not strong enough, the packaging will be damaged and will affect The appearance of foods and foods are contaminated with micro-organisms, and the entrance of light, air, etc. provides living conditions for micro-organisms, which shortens the shelf life of foods or directly deteriorates the quality of foods. Therefore, ensure that the packaging material has enough strength so that the food packaging will not be damaged during the circulation.

2. Sterilization resistance

Microorganisms are the main cause of food spoilage and deterioration. In order to ensure the health and safety of foods, foods and packaging materials are sterilized in the packaging process. Therefore, it is required that the packaging material needs to pass heat or radiation required for sterilization, and the material is required not to be damaged in the sterilization process, and it is ensured that the sterilization is performed uniformly and completely.

3. Good barrier property

Barrier property is one of the important properties of food packaging materials. In order to better extend the shelf life of foods, it is necessary to block the entry of microorganisms and air and moisture that allow the growth of bacteria, so the packaging materials must have good barrier properties.

4. Good heat and cold resistance

For foods that need to be frozen, if the cold resistance does not meet the requirements, the original properties of the materials cannot be maintained when stored under cryogenic conditions. The brittleness will reduce the strength of the packaging materials and cause the packaging bag to be damaged and cannot be used for foods. Protective effects.

In addition, in order to better sell food, it is also necessary to decorate food packaging. Therefore, it is required that the pattern on the packaging material be still clear and colorful after sterilization, and does not affect the food sales.

(II) Food Aseptic Packaging Materials

Paper material

For the packaging needs can be made into paper boxes. Paper materials are lightweight, low cost, and can be used in the aseptic packaging process of cakes. However, the waterproof and airtight properties of paper materials are not good. They are used once. They are easy to recycle after use. Moreover, paper materials can be decomposed in nature and materials are more environmentally friendly. It is applied to the aseptic packaging process of bags of milk, pastries and other foods.

2. Metal materials

Mainly aluminum plate, heavy material, high cost, waterproof and air tightness, but not easy to clean and sterilize. In the process of aseptic packaging of canned foods such as canned meat, filled soft drinks, and filled beer, metal cans can be made for packaging.

Glass material

Material weight, low cost, transparency, observable material inside, waterproof and airtight, but fragile, inconvenient to carry and sterilize, but can be reused and recycled. Widely used in canned fruit, bottled milk, bottled beer and other food packaging, for the packaging needs, generally glass bottles.

Plastic

Its light weight, low cost, and transparency make it possible to observe the interior of the material with good water and air tightness. However, plastic materials are mostly used for one-time use and are not easily recovered after use. Since plastics are all synthetic polymers, they are difficult to be decomposed by microorganisms in the soil, and the environment is relatively polluted. Widely used in puffed food, bagged mustard, bottled beverages and other food packaging.

5. Composite materials

Different from the previous several materials, based on the development of science and technology, food packaging materials have also been correspondingly developed. In order to better package foods, be easy to carry, and have low prices, they have evolved from simple packaging materials to composite materials. Composite material refers to a solid material composed of two or more kinds of materials. The material has advantages and disadvantages in performance, and is superior to the original composition material to satisfy various requirements. There may be metal-metal composite materials, metal-non-metal composite materials, metal-plastic composite materials, paper metal-plastic composite materials, non-metal-non-metal composite materials, and paper-plastic composite materials. Because the paper metal plastic composite material has the advantages of paper metal and plastic in overall performance, it is widely used in the food packaging process.

(iii) Sterilization of Sterile Packaging Containers

There are four main methods for sterilization of packaging materials: heat sterilization, pharmaceutical sterilization, ultraviolet sterilization, and radiation sterilization.

1. Heat sterilization

The superheated steam at a temperature of 130° C. to 160° C. is sprayed on the containers to be sterilized, and the sterilization operation is completed in several seconds. Heat sterilization has the advantages of non-toxicity, no residual harmful substances, but it is only suitable for heat-resistant containers, such as metal containers, glass containers, etc. Therefore, there are not many applications at present.

2. Sterilization

The use of chemical agents that have a killing effect on microorganisms and are harmless to the human body is used for sterilization operations. Hydrogen peroxide (hydrogen peroxide), ethanol, etc. are generally used. Hydrogen peroxide has strong adaptability to packaging materials and high sterilizing safety, and is the most widely used sterilization agent for aseptic packaging containers.

3. Ultraviolet sterilization

Ultraviolet light can cause microbial cells to absorb ultraviolet light, chemical changes in the intracellular components, causing cytoplasm degeneration and death. This sterilization method can be performed at room temperature, cost-effective, high security, very suitable for sterilization of packaging materials, of which the wavelength of 250 - 260 mm UV sterilization ability is the strongest. However, the ultraviolet ray is susceptible to the flatness of the surface of the object, and the bactericidal effect varies greatly with the species.

4. Radiation sterilization

The γ-rays emitted from Co60 are treated at room temperature and have strong penetrating power and high bactericidal reliability. This sterilization method is costly, but the method is both efficient and safe.

When selecting the sterilization method for packaging containers, the packaging materials of different containers, the different packaging needs of the food, the price requirements, and the characteristics of each sterilization method should be taken into account. Each sterilization method can also be combined to achieve a better sterilization effect. For example, the carton is first sterilized with ethylene oxide, and then hydrogen peroxide is applied before filling, and then heated and blow dried; the plastic bag-like container is often used in combination with ultraviolet sterilization and chemical sterilization.

Fourth, aseptic packaging equipment and environment

Sterile packaging requires foods without added preservatives, according to the food packaging requirements, in the aseptic state, the sterilized food using packaging machinery, into pre-sterilized or aseptically processed packaging containers Seal the food in an environment that is airtight, insensitive to microorganisms, or even opaque, and store it at room temperature for long periods of time. Therefore, ensuring the sterility of the packaging environment and packaging equipment is the premise of the entire packaging process.

The aseptic packaging environment must first ensure the sterility of the packaging machinery. The packaging machine must be sterilized prior to use, sterilized with hot alkaline water, diluted with diluted hydrochloric acid, and then rinsed with hot water. If the packaging machinery is not in use, the microorganisms will multiply. Therefore, after cleaning the packaging machinery, the moisture or liquid residue must be dried to provide no living conditions for the microorganisms. In order to ensure the sterility of the operating environment, chemical and physical sterilization can be used to prevent microorganisms from entering the operating environment. Therefore, an aseptic chamber must be equipped with an air filter device and an ultraviolet ray sterilizer to perform regular UV irradiation to ensure the clean room. Cleanliness meets the required standards. In the process of transport, the tightness and pressure of the takeover place, valves, and equipment must be maintained to ensure that air cannot enter.