Under the internal requirements of the hottest foo

Internal requirements of food packaging (Part 2)

3. Mutual barrier

mutual barrier contains two meanings. One is the small package food in the large package, and this small package food has its own characteristics. In order to prevent the food with different characteristics from tasting in the package, the inner package must be barrier. The other is to make the food inside the package and various substances inside and outside the package impervious through packaging, that is, the substances inside the package do not overflow, and the substances outside the package do not penetrate

many foods need to be barrier to each other. The better the barrier, the longer the shelf life. Mutual barrier is very important in non active processed foods

4. Selective barrier

selective barrier is discovered through research in recent years. It requires the use of packaging materials according to the performance of food, so that internal and external substances selectively block the penetration of relevant ingredients, allowing some ingredients to penetrate through, while some external ingredients cannot pass through. In fact, different material molecular diameters are used to make the packaging materials play the role of screening. When the molecular diameter of some substances is greater than a certain value, the molecules of the substance can be blocked; When the molecular diameter is less than a certain value, the substance can pass through

many foods need selective barriers to achieve their packaging purposes. For example, the preservation of fruit and vegetable food requires its packaging to have this characteristic

5. Barrier ingredients and substances

the quality of food is realized through its own ingredients and processing methods, and its flavor is preserved and reflected in the effective time. For example, it can be reflected through human vision, touch, taste and relevant instrument detection

there are many substances that affect the quality of food storage and need to be blocked. Depending on the type of food and the processing method, it mainly includes: air, moisture, water, grease, light, heat, peculiar smell, harmful gas, bacteria, dust, etc. once these substances penetrate into the food in the package, they will change the appearance of the food in light, and in serious cases, they will change the taste of the food, produce chemical reactions, form harmful substances, and eventually cause the food to rot and deteriorate

6. Problems to be considered in barrier requirements

barrier is an important technical measure to ensure the quality of Xiangtan. The most important point for food packaging is that while USB is the most popular and successful external equipment, packaging materials and containers must also ensure that they are non-toxic and free of volatile substances, that is, they are required to have stable and structural components. In addition, during the implementation of the packaging process, substances and ingredients that have chemical reactions with food ingredients cannot be produced. Furthermore, during the storage and transfer of packaging materials and containers, chemical changes should not occur due to the changes of different climate and environmental factors

III. respiratory requirements

there are many foods that have life. Therefore, this kind of food must keep breathing during packaging and storage. For example, live food, non processed food, etc

1. Concept of respiration

respiration is the most basic physiological function of fresh food in packaging and storage. Respiration is a complex physiological change process in the storage and packaging of fresh food, that is, the complex organic substances in its cell tissues are slowly decomposed into simple organic substances under the action of enzymes, and release energy at the same time. Part of this energy is used for normal physiological activities of the body, and part is emitted in the form of heat. Test method for adhesive tensile bond strength: therefore, respiration is a process of nutrient consumption and a slow biological oxidation process

the respiration of food depends on the absorption of oxygen and the discharge of carbon dioxide. The normal respiration of food is the condition for ensuring its quality and quantity and prolonging its shelf life in storage. The breathing intensity and oxygen supply of fresh food can be controlled through packaging, so that it can be well stored

2. Respiratory intensity and effect

respiratory intensity 2. Electromechanical: it is the engine that controls the operation of components of the fatigue testing machine, and it refers to the intensity of respiratory effect or the speed of respiratory speed. Generally, it is measured by the milligram of oxygen consumed or carbon dioxide released by 1kg of active body within 1 hour

respiratory intensity has a great impact on food packaging and storage. The greater the respiratory intensity, the more organic matter stored in food will be consumed, and the more respiratory heat will be generated, which will promote the aging process of active food. Excessive breathing heat can raise the temperature of the storage environment, causing the product to deteriorate due to heat, thus shortening the shelf life of the commodity. On the contrary, the smaller the respiratory intensity is, the weaker the respiratory effect will be. Too weak respiration will destroy the normal life activities, lead to the occurrence of physiological hazards, reduce the resistance to microorganisms, and also accelerate the aging process of food activities, thus greatly reducing the shelf life. It can be seen that too high or too low respiratory intensity of active food will affect the storage period or shelf life of food. The factors related to respiration include the maturity of active food, storage environment temperature, environment and gas composition in packaging, etc

3. Respiratory form and function

the respiratory form of active food can be divided into aerobic and anaerobic respiration

1) aerobic respiration

aerobic respiration is the respiration under the condition of aerobic supply. Active AIDS absorb the oxygen in the surrounding air through respiration, oxidize and decompose the kind sugars, carbohydrates, proteins, fats and organic matter in the body into carbon dioxide and water, and release energy at the same time. Part of the energy released by aerobic respiration becomes respiratory heat. In case of poor ventilation or no cooling measures, this kind of respiratory heat will gradually accumulate, and the body temperature of intellectual food will increase, which will strengthen the respiratory function, thus increasing the amount of heat released, and further strengthening the respiration. In this way, a vicious cycle will occur, which will eventually lead to the aging, decay and deterioration of active food. It can be seen that aerobic respiration is a normal form of respiration, but in order to achieve a long shelf life, its oxygen content must be controlled to keep it at an appropriate low level. In terms of packaging measures, 9. The smooth and clean pipeline is realized by the oxygen permeability of the packaging, and the heat insulation and other functions of the packaging are used to reduce the respiratory heat, so as to prolong the shelf life

2) anaerobic respiration

anaerobic respiration is respiration under anoxic conditions. Aerobic respiration in general, the organic matter in the active food is not completely oxidized, but turns into ethanol, lactic acid, etc., and releases a small amount of energy at the same time. Studies have shown that anaerobic respiration provides little energy. In order to obtain energy to maintain its physiological activities, active food can only decompose more respiratory substrates, that is, consume more nutrients. The consumption of these nutrients accelerates the aging and decay of active food. In addition, when the produced alcohol, ethanol and lactic acid are accumulated to a certain extent, they will cause cell poisoning, cell death and renovation metabolism activities are blocked, and finally lead to the decay and deterioration of active food. In fact, anaerobic respiration is fermentation. Therefore, for better storage and packaging, anaerobic respiration should be avoided, or relevant ingredients should be added to anaerobic respiration packaging to control fermentation

the breathing requirements of food are the requirements for the air permeability of packaging materials or packaging containers, the temperature of packaging and storage environment, and the gas composition. Different food requirements for packaging are mainly to use packaging to control breathing

source: China packaging industry author: guoyufeng