The difference between vacuum packaging and modified atmosphere packaging

The difference between vacuum packaging and modified atmosphere packaging

1. Vacuum packaging, also known as decompression packaging, is to extract and seal all the air in the packaging container to maintain a high degree of decompression in the bag. The scarcity of air is equivalent to the effect of hypoxia, so that microorganisms have no living conditions, so as to achieve fresh fruit, no pollution. The purpose of disease rot. The current applications include vacuum packaging in plastic bags, aluminum foil packaging, glassware, plastic and its composite packaging, etc. Packaging materials can be selected according to the type of item. Since fruit is a fresh food, it is still undergoing respiration, and high hypoxia can cause physiological diseases. Therefore, vacuum packaging is less used for fruit.

The mechanism of vacuum packaging: its purpose is to reduce the oxygen content in the package, prevent the mildew and deterioration of the packaged food, maintain the color and fragrance of the food, and prolong the shelf life.

The main function of vacuum packaging is to remove oxygen to help prevent food spoilage. The principle is also relatively simple, because the mildew and spoilage of food is mainly caused by the activity of microorganisms, and the survival of most microorganisms (such as mold and yeast) requires oxygen. , and vacuum packaging uses this principle to pump out the oxygen in the packaging bag and food cells, so that the micro-materials lose the "survival environment". Experiments have proved that when the oxygen concentration in the packaging bag is ≤1%, the growth and reproduction speed of microorganisms will drop sharply, and when the oxygen concentration is ≤0.5%, most microorganisms will be inhibited and stop multiplying. (Note: vacuum packaging cannot inhibit the reproduction of anaerobic bacteria and the deterioration and discoloration of food caused by enzymatic reactions, so it needs to be combined with other auxiliary methods, such as refrigeration, quick freezing, dehydration, high temperature sterilization, irradiation sterilization, microwave sterilization, salt pickled etc.)

2. Modified atmosphere preservation, as the name suggests, uses the method of controlling the proportion of gas to achieve the purpose of preservation and preservation. The modified atmosphere preservation technology is a technology that prolongs the storage life and shelf life of food by adjusting the ambient gas. Physiological and biochemical processes of food spoilage and the activities of microorganisms.

The key to the modified atmosphere preservation technology is to regulate the gas. In addition, two very important control conditions, temperature and relative humidity, must also be considered while selecting the composition and concentration of the regulating gas. Not only their individual effects, but also the combined effects of the environment as a whole consisting of various conditions must be paid attention to.

At present, there are two main methods commonly used in China:

1. CA air-conditioned storage and preservation (air-conditioned fresh-keeping cold storage) is researched by domestic high-tech enterprises, using mechanical equipment to artificially control the gas in the storage environment of the air-conditioned cold storage to achieve fruit preservation. Modified atmosphere fresh-keeping cold storage requires precise regulation of the concentration of gas components required by different fruits and strict control of temperature and humidity. The temperature can be the same as the storage temperature of the refrigerator, or slightly higher than the temperature of the refrigerator to prevent low temperature damage. The combination of modified atmosphere and low temperature, the preservation effect (color, hardness, etc.) is better than ordinary refrigeration, and the preservation period is significantly prolonged.

2. MA storage and preservation (modified atmosphere preservation in plastic film bags, also known as modified atmosphere preservation packaging) According to the physiological characteristics of the food and the needs of preservation, the food is stored in a suitable proportion of packaging to prolong its preservation period. It is used in fresh fruit and vegetable preservation, and grows at a rate of 20% every year. The combination of fresh-keeping packaging and cold storage is basically close to the effect of air-conditioned fresh-keeping cold storage. There are two types of MA packages: one is passive modified atmosphere packaging, that is, the fruit wrapped in plastic film uses respiration to reduce the oxygen content and adjust the ratio of oxygen and carbon dioxide by exchanging gases through packaging; the other is active modified atmosphere, That is, according to the respiration rate of different fruits, the mixed gas is filled, and the film with different air permeability is used. However, due to the complex technology and high requirements for the variety and performance of packaging materials, it has not been widely used in my country.