New Technology and Materials for Fresh Food Packaging (I)

With the development of society and the improvement of the quality of life of the people, the demands for fresh foods are getting higher and higher. As the world trade develops increasingly today, higher requirements are placed on fresh food storage and transportation, and the demand for fresh foods The volume is also rapidly increasing, so the market for fresh-keeping packaging is constantly increasing and the range of applications is also increasing. Countries around the world attach great importance to food preservation technology. Chinese and foreign scientists and researchers who are dedicated to research on this technology have increased their efforts in food preservation and have made many achievements. In recent years, many new and practical fresh-keeping packaging materials and technologies have been developed. The preservation of fresh foods is a practical and urgent problem that needs to be solved. At present, research on preservation of fresh fruits and vegetables and food packaging mainly focuses on materials selection and technology. However, it is the goal pursued by fresh-keeping packaging to make fresh-keeping packaging more effective, to simplify the process, to save costs, and to increase efficiency. As a result, fresh-keeping packaging technology has become diversified, new and rationalized. Here are some of the high-tech and new fresh-keeping packaging materials for food preservation packaging.

1. Fresh-tempered atmosphere-changing film packaging for fruits and vegetables: The self-regulating atmosphere-modified film packaging is a new type of modified atmosphere storage and sales packaging developed in recent years. The principle is to use fruits and vegetables to seal and breathe and consume oxygen after sealing. Release the characteristics of carbon dioxide, reduce the oxygen content in the bag, increase the concentration of carbon dioxide, to achieve the purpose of spontaneous gas, thereby prolonging storage and keeping fresh. The packaging mainly involves three factors: the permeability of the packaging material to oxygen and carbon dioxide; the respiration rate, moisture content, and evaporation rate of different fruits; and the storage temperature of the packaged product. The package is transparent, breathable, moisturizing, etc., and is widely used in post-harvest fresh-keeping packaging of fresh fruits and vegetables.

2. Herbal Medicine Fruit and Vegetable Preservation Paper Technology: This is a kind of special packaging paper. It is made by coating, pulverizing, and powdering a variety of natural plants, Chinese herbs, and powdered liquids onto special fruit and vegetable packaging papers to preserve their freshness and shelf life. Far more than the existing fresh fruit and vegetable packaging paper, has a good role in insecticidal sterilization. Moreover, the paper has the characteristics of easy degradation, no pollution to the environment and the like, and its manufacturing method is relatively simple, and the materials are convenient and low in cost, which is suitable for the production of small and medium-sized enterprises. It is a fruit and vegetable fresh-keeping packaging technology with obvious economic and social benefits.

3. Micro-perforation technology: Many fresh fruit and vegetable products are highly repellent even if they are packaged using high-permeability polyolefin films, because the packaging film cannot provide commercial standard gas exchange, especially when the product is loaded into the tray. Due to the airtightness of the tray, only a certain amount of gas can be stored before capping. Therefore, in order to prevent this kind of hyperbreathing from happening, one of the ways to increase the permeability of the packaging film is to use a slightly high-permeability film while reducing the moisture.

4. Natural Preservatives for Fruits and Vegetables: Preservatives for fruits and vegetables can be divided into two major categories, namely chemical synthesis and natural fruit and vegetable preservatives. For a long time, people mainly used chemical synthetic substances as preservatives to preserve the stored fruits and vegetables. Although it has a good preservation and antiseptic effect, many chemical synthetic substances have certain adverse effects on human health, and even have toxicity such as carcinogenesis, teratogenicity, and mutagenesis. In recent years, research and development of natural fruit and vegetable preservatives have been widely carried out both at home and abroad. Among them, the preservation of flavoring plants has attracted increasing attention. Its preservation, antiseptic and antibacterial effects depend on the essential oils of the active substances found in the rhizomes, leaves and flowers of these plants. In addition, some Chinese herbal decoctions or soaked extracts can be used to preserve fresh fruits and vegetables such as citrus, apple and grass poison. Garlic can be used for fresh-keeping of citrus fruits, phytic acid and preservatives formulated with phytic acid as raw materials, which can prolong the storage period of perishable fruits and vegetables such as strawberries, bananas, and honeydew melons, and can better maintain the freshness of fruits and vegetables.

5. Freeze-drying technology: vacuum freeze-drying dehydration technology is a high-tech for food, medicine color protection, preservation, durability, taste protection, referred to as freeze-drying technology. It freezes the water-containing material under low temperature conditions, and then heats it under high vacuum to sublimate the solid ice and remove the moisture from the material. When the food is immersed in water, it can be recovered quickly, like a fresh product. The original colors, fragrances, tastes, nutrients and physiologically active ingredients are retained to the maximum. This food is inherently superior to traditional hot air drying, spray drying, vacuum drying and other dehydrated foods. From the perspective of storage and transportation, it is far better than quick-frozen foods and canned foods. Since freeze-dried foods are completely dehydrated, they can be stored for a longer time without any preservatives. However, because freeze-dried packaging is porous and loose, it is prone to absorb water. Therefore, moisture-proof, oxygen-proof, and shatterproof packaging techniques should be adopted for packaging.

6. Edible plastic wrap technology: Scientists developed an edible preservative for fruits and vegetables. It is a translucent emulsion formulated with sucrose, starch, fatty acids and polyesters. It can be applied to the surface of citrus, apple, watermelon, banana, tomato and eggplant by spraying, brushing or dipping. As this antistaling agent forms a layer of sealing film on the surface of fruits and vegetables, it can prevent the exchange of oxygen, moisture, carbon dioxide and other substances between the fruit and vegetable tissue and the outside world, prolong the rot time of fruits and vegetables, and thus play a role of preservation, reducing the transportation and storage of fruits and vegetables. Wasted phenomenon. And people can eat directly with the plastic wrap, because the film is soluble in water, it can also wash it with water to eat.

7. High-temperature treatment preservation method: Britain has invented a kind of high-temperature storage technology for bulb vegetables. This technology uses high temperature to inhibit the germination of bulbous vegetables, the temperature of the storage room is controlled at 23 degrees Celsius, relative humidity of 75%, so that long-term storage can be achieved. According to reports, onions can be stored under these conditions for 8 months. However, vegetables are prone to produce saprophytic fungi and cause lesions under these conditions. At present, the United Kingdom is studying how to control this saprophytic fungus.

8. Trehalose preservation technology

Recently, a new technology has been introduced abroad that uses trehalose to preserve food. The UK's agricultural, fishery and food sectors have been officially approved for the use of this new technology after considerable time trials. Trehalose, also known as yeast sugar, is a monosaccharide consisting of two glucose molecules linked together. Its main feature is that it can prevent food spoilage and deterioration, and it can preserve freshness, and it can greatly extend the time of food preservation. The principle of trehalose preserving food for a long period of time is that it can form a special film at room temperature and seal the food. At the same time, it will release new liquid to moisten it and kill the original bacteria and the contaminated bacteria. (on)

Source: China Packaging News