New technology and materials for fresh-keeping pac

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New technology and new materials for food preservation packaging (Part 2)

it is very stable under conventional humidity, and it can also radiate external heat. Therefore, the effect of using trehalose to preserve food is not only very ideal, but also does not need special equipment, and the operation is very simple. As long as you pay attention to avoid contact with water, you can preserve it for a long time. Trehalose exists in yeast, and yeast can reproduce in large numbers, so trehalose is easy to obtain. Using trehalose to preserve food can successfully solve the problems of color loss, taste change, meat dryness and hardness deterioration, vitamin damage and so on when fresh food is frozen and dehydrated. At the same time, the degree of processing is also very simple. As long as all kinds of food just harvested are removed from impurities, sprinkled with trehalose, stirred or flipped several times, so that trehalose is evenly covered with food, and then processed, so that the food can be put on shelves for sale, Or store it in the food basket for a long time without worrying about deterioration. When eating, take out the food and wash it again. The original color will be restored immediately and the taste will be as delicious as before. The vitamins contained in meat remain intact, and its color, aroma, taste and nutritional composition have not changed, which is no inferior to fresh food. If this technology is further developed and improved, it will be widely used, and its prospect is very broad

9. Decompression and preservation. In recent years, a technology of decompressed storage and preservation of fruits and vegetables has been rapidly and widely used abroad. The principle of this preservation method is not complicated. It mainly applies measures such as reducing air pressure, cooperating with low pressure and high temperature, and using low pressure air for circulation, so as to create a favorable storage environment for fruits and vegetables. The low air pressure in the storage room is generated by pumping the indoor air with a vacuum pump, and the low air pressure is controlled below 13.3 kPa, with a minimum of 0.106 kPa. The relative humidity in the air is controlled by the indoor humidifier, which is generally more than 90%. Because the extraction reduces the indoor oxygen content, the respiration of fruits and vegetables is maintained at the lowest level, and at the same time, some indoor gases such as carbon dioxide and ethylene are excluded, which is conducive to the long-term storage of fruits and vegetables

10. Artemisia argyi antibacterial fresh-keeping bag. The United States uses Artemisia argyi to produce a new type of food preservation bag, which can be reused and eventually decomposed by microorganisms. Artemisia argyi is a kind of wild plant, which has antibacterial, mildew proof, insect proof and medicinal functions. According to the information provided by the company that produces mugwort fresh-keeping bags, the newly developed food fresh-keeping bags are made of film made of 60% degradable plastic, 20% mugwort powder and 20% additives. Putting vegetables, fruits and other foods in this fresh-keeping bag and placed in the refrigerator can ensure that the food is in an antibacterial, mildew proof and insect proof environment, and can extend the fresh-keeping period of food by two times. If the fresh-keeping bag is dirty, it can be reused after brushing until it is broken. After being discarded, the fresh-keeping bag can be decomposed by microorganisms

11. A new fruit preservative. An agricultural research center in the United States has developed a new fruit preservative. This preservative is prepared by mixing 4-ethyl resorcinol extracted from natural plants and calcification in proportion. It has the effect of inhibiting biological activity and enzyme oxidation, so it has good fresh-keeping effect. Experiments have proved that peeling and cutting fresh apples and spraying the preservative can make the apple slices not change color for several weeks even at a temperature of about 20 degrees Celsius, which is also applicable to the preservation of peaches, bananas and other fruits. In order to keep fruits and vegetables fresh during air transportation, an American company has invented a new method to reduce the oxygen content and increase the nitrogen content in the packaging box. This new type of packaging box with air conditioning performance for air transportation has a special film in it. The film fiber can absorb oxygen molecules and let nitrogen through. Therefore, after the air enters the packaging box through the film, the nitrogen content in the box can be as high as 98%, High content of nitrogen can slow down the respiration of fruits and vegetables, and achieve the purpose of long-term preservation. An American food company used cheese and acetyl monoglyceride extracted from vegetable oil to make an edible package. This is a transparent and tasteless covering film, which can be pasted on the surface of cut fruits and vegetables to prevent dehydration, blackening and microbial invasion of fruits and vegetables, so that cut fruits and vegetables can remain fresh for a long time

12. Fresh flowers packaging. In view of the problem that flowers are easy to wither, Israel has recently developed a new fresh-keeping packaging method for flowers. This method is to improve the plastic with bubbles, which is usually used to pack computers and electronic instruments, to make a new packing filler, and fill it in the box containing flowers as the lining, which can not only reduce the temperature in the box by several degrees, but also slow down the air exchange inside and outside the box, playing a good role in keeping fresh

13. Toxic plastic fresh-keeping film can be tested. Canadian toxin plastic board company invented a kind of food preservative film that can detect whether the food is spoiled and poisonous. This plastic cling film coated with a chemical deforms (from round to flat) when it encounters some toxins

after determination, this fresh-keeping film can detect Salmonella, Aspergillus, Escherichia coli and Listeria. The chemicals applied are non-toxic, will not pollute food and will not affect human health

14. Negative oxygen ion food preservation machine. Japan Changbao electric appliance company has developed a negative oxygen ion food preservation machine, which uses negative oxygen ions and ozone generated in high-voltage negative electrostatic places to achieve the purpose of preservation. Negative oxygen ions can effectively inhibit the enzyme activity in the metabolic process of fruits and vegetables, and reduce the ethylene production in fruits and vegetables with ripening effect; At the same time, ozone not only has the effect of disinfection and sterilization, but also can effectively inhibit and delay the decomposition of organic matter, so it can prolong the storage period of fruits and vegetables

15. Irradiation fresh-keeping packaging. It uses ionizing rays produced by nuclear technology to irradiate the packaged food while artificially making it move forward and backward, which can effectively inhibit or eliminate bacteria, fungi and many microorganisms in the food, so as to maintain the original quality, flavor and nutritional value of the food. After the sealed fruits, vegetables and fish meat are irradiated with the specified dose of radiation, the storage period at room temperature is significantly prolonged due to the inhibition of microbial communities and the inhibition of the ripening process. Tomatoes irradiated with a dose of 4000 Gy of gamma rays can be stored for 30 days at 8 ℃. In the environment of low vacuum (5.30 kPa ~ 8.0 kPa), the semi-finished beef or pork can be stored at 3 ℃ ~ 5 ℃ for 40 days and 60 days respectively when irradiated by gamma rays with doses of 4000 Gy and 6000 Gy with rib 1 true hole. Compared with heating sterilization and cold storage, radiation packaging has food characteristics, can be kept intact for a long time, and there is no chemical carcinogen residue; New packaging can be adopted and packaged food can be directly irradiated; It has the advantages of automatic production. Research shows that as long as the irradiation dose does not exceed 10000 Gy, there is no adverse effect on any food, and the safety of human body can be guaranteed. China has built a scientific and safe Irradiation Center, and the irradiation technology has reached the world advanced level. It is believed that the irradiation fresh-keeping packaging in China will get new and greater development in the future

16. Modified atmosphere fresh-keeping packaging: a modified atmosphere fresh-keeping packaging bag for fruit and vegetable food packaging has appeared in the European market in recent years. The combination ratio of oxygen, carbon dioxide and nitrogen in this high oxygen spontaneous modified atmosphere packaging bag can be adjusted according to the physiological characteristics of different fruits and vegetables, such as 80% - 90% oxygen and 10% - 20% carbon dioxide for perishable fruits and vegetables. This kind of package can inhibit enzyme activity and prevent browning of fruits and vegetables; Prevent fermentation caused by anaerobic respiration and maintain the quality of fruit and vegetable food; It can effectively inhibit the growth of aerobic and anaerobic microorganisms and prevent decay. Fresh mushrooms are packed in high oxygen regulated packaging bags, and the shelf life can reach 8 days at a temperature of 8 ℃

17. Long acting mould proof and antibacterial paper. Mold proof packaging paper, which is usually used for the packaging of food, fruits and vegetables, is a kind of reagent to prevent the growth of biological mold added in the manufacturing process of paper, which can prevent the deterioration of substances caused by biological mold. It is packaged with articles at room temperature, which can form an antibacterial atmosphere around the articles, which can not only destroy the survival of some mold harmful to human health, but also do not affect human health, non-toxic, tasteless, non corrosive, so as to achieve the purpose of mold prevention, It is a new breakthrough in the use of chemical antibacterial agents in recent years. The long-term mold proof paper produced by a Japanese company is a new type of packaging paper that can prevent food from mildew and deterioration for a long time without damaging food flavor. The paper is made by dissolving special monoglyceride with its compounds, dissolving it as an effective component in an aqueous solution of water and ethanol, spraying or soaking it on the paper, and finally heating and drying it. It can be used to pack all kinds of food. In addition, a Japanese company has produced a new type of mould proof and antibacterial packaging paper that can prevent food from mildew and deterioration for a long time and does not damage food flavor. The paper is made by dissolving the special monoglyceride with its compounds, dissolving it as an effective component in the aqueous solution of water and ethanol, then spraying or soaking it on the paper, and finally heating and drying it. It can be used to pack all kinds of food. The company also manufactures a kind of anticorrosive paper that can be used for food packaging. The preparation method is as follows: first immerse the base paper in an ethanol solution containing 20% succinic acid, 33% sodium succinate and 0.07% sorbic acid, and then dry it. The food packed with brine with this kind of paper can be stored at a high temperature of 38 ℃ for 3 weeks without deterioration

18. Fruit preservation paper. This is a kind of fresh-keeping paper developed and produced in Singapore, which contains antibacterial and bactericidal agents. It is used to pack apples. After half a year, the fruit is still full, with a green background, as if it had just been picked. There is also a kind of fruit preservation paper that can preserve oranges for 3 months and litchi for more than 30 days. In addition, the fruit fresh-keeping paper developed by Showa chemical company of Japan infiltrates a mineral concentrate with phosphoric acid as raw material into a water absorbent paper bag. Use this paper container to pack vegetables and fruits. During transportation, vegetables and fruits can get nutrition from mineral concentrate. Practice has proved that calcium phosphate can absorb ethylene and carbon dioxide gas, inhibit the decomposition of chlorophyll, and play a fresh-keeping effect

19. Antiseptic and fresh-keeping packaging paper. Sweden orenson Paper Co., Ltd. launched high permeability food packaging paper. There is a thin layer of fluororesin on the inner and outer layers, which is free from water and oil. Wrapping the food can make the inner and outer temperatures the same. Putting it in the refrigerator can better maintain the original flavor of the food, as fresh as ever. A Japanese company first immersed the paper in an ethanol solution containing 2% succinic acid, 33% sodium succinate and 0.07% sorbic acid, and then dried it to make food packaging paper, which can be used to package food and can be stored at 38 ℃ for 3 weeks without deterioration

20. Porcelain fresh-keeping wrapping paper. It combines inflatable packaging technology with advanced ceramic paper packaging technology. Vegetables are packed in thin-film bags with porcelain paper. After vacuuming, the air in the bag is removed first, and then filled with SuiXing gas. After the packaging bag is sealed, the porcelain paper continuously emits harmless long wave infrared radiation, thereby limiting the activity of bacteria in water molecules and absorbing them at the same time

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