Food packaging and food packaging industry
DATE：2019/12/23 8:57:20 / READ： / SOURCE：This station
The process of using plastic to package food products mainly includes four industrial industries: the first industry is the production of plastic resin and sea film; the second industry is the processing industry of flexible and rigid packaging materials; the third industry is the mechanized production of packaging Industry; the fourth industry is the food processing industry. In the first industrial industry, raw materials such as petroleum, coal, and natural gas were used to synthesize polymerizable low-molecular compounds, which were then polymerized into various resins, which were then processed into single or multi-layer composite sea films for packaging in food processing plants. For food. The packaging machinery industry includes not only the manufacturing of packaging material molding machinery and equipment, but also the manufacturing of packaging machinery that combines food with packaging materials. Many places also include the manufacture of cores for secondary processing of packaging materials, such as printing Machine, thermoforming machine, welding machine, bag making machine, etc. The earliest, food was packaged with flexible packaging materials such as single-layer plastic film, cellophane, or paper. Currently, multi-layer composite flexible packaging and various multi-layer rigid containers are used for packaging. The packaging methods also vary according to the freshness and shelf life requirements of the packaged food: from frozen packaging, deaeration packaging, gas replacement packaging, aseptic packaging, N2 gas packaging, vacuum packaging, etc. to different packaging , Such as: inner bag, compound tank, vertical bag, microwave oven, electric furnace and other packaging materials.
The cause of food spoilage is the proliferation of bacteria in food (Table 7-1-1). To prevent bacteria from growing in food, food can be stored for a long time. For this reason, conditions that inhibit the growth of bacteria can kill bacteria, such as : Frozen food, because bacteria need suitable temperature conditions for breeding. Generally, food can be kept fresh for a long time in a freezer with a temperature of 20 ° C. Bacteria are hibernated at such low temperatures, and no spoilage caused by activity occurs. Another condition for bacterial growth and reproduction is moderate moisture. We use water vapor pressure at a certain temperature in food as か, and saturated water at this temperature.
The vapor pressure is, then か / か o is the water activity of the food. Foods with water activity below 0.65 are called dry food. Water
Foods with an activity ranging from 0.65 to 0.90 are intermediate moisture foods, and foods with a moisture content greater than 0.9 are hydrated foods. Bacteria in dry foods are not easy to survive, while foods with water activity exceeding 0.65 are easily invaded by bacteria and will mold and deteriorate. Yuzao can increase the shelf life of food. The third condition for the growth and development of bacteria is the presence of oxygen. The deaeration package can be kept fresh. When the oxygen content is below 2% and the CO2 content is above 7%, the food and bacteria are in hibernation. After fresh vegetables and fruits are picked, the cells are still growing. The plant cells produce ethylene gas during the growth process. This gas has a ripening effect. If fruits and vegetables are ripened by ethylene, they will soon become overripe. , Overripe results in fruit rot
Author：admin