Research progress of straw degradable biological p

Qu Weiguo: Research Progress of straw degradable biological packaging materials

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core tip: plastic packaging materials in today's society cause serious white pollution, destroy the ecological environment, and cause a waste of resources. Biological packaging materials produced from natural degradable materials such as straw starch, cellulose, protein and chitin have the characteristics of rich sources, low price, no pollution and easy decomposition, and have a wide application prospect

[China Packaging News] plastic packaging materials in today's society cause serious "white pollution", destroying the ecological environment and causing a waste of resources. Biological packaging materials produced from natural degradable materials such as straw starch, cellulose, protein and chitin have the characteristics of rich sources, low price, no pollution and easy decomposition, and have a wide application prospect

plastic products have the characteristics of impermeability, impermeability, acid and alkali resistance, light weight, high strength, durability and low price, so they have become the most widely used material in the packaging industry. In addition to production enterprises, retailers, farmers' markets and even fast food stalls in the streets all use plastic bags and foam plastic boxes as their main packaging materials. Different types of vertical and horizontal products can be selected according to the requirements of customers. About half of these products are discarded in the environment and generally take 200 years to degrade. Another kind of widely used packaging materials are paper and plastic products. Most of these paper and plastic products are discarded in the environment after use. Even under the action of microorganisms, three specimens from each batch of joints with the same specification need to be randomly selected for static tensile test for 80 years before they can be degraded. This kind of refractory plastic products is discarded in the environment, resulting in a serious consequence of a huge waste of resources and environmental pollution

in view of this situation, scientists put forward the concept of "environmental packaging". This material should not only pursue good use performance, but also deeply understand the limitations of natural resources and reduce waste emissions as much as possible, and reduce the impact on the environment as much as possible in the whole process of material extraction, preparation, use, waste disposal and regeneration. It is a material that takes full account of environmental, ecological and resource factors. This kind of material has the characteristics of saving resources, reducing pollution, having little ecological impact, being reusable and degradable

in recent years, countries around the world have successively developed some degradable plastics and biomaterials, which has played a great role in promoting the development of the packaging material industry in various countries. While degradable plastics (mainly adding starch, cellulose, photosensitizer, biodegradable agent and other additives to plastics) have the disadvantages of consuming a lot of food and cannot eliminate visual pollution. Moreover, the existence of plastic micro materials makes its degradation speed slow in the soil and cannot be recycled in time. Therefore, the application prospect of degradable plastics has limitations, and the most promising is biological packaging materials

classification of biological packaging materials

starch, as a natural polymer, has rich sources and low prices. It is decomposed into glucose under the action of microorganisms, and finally 12 Measurement error: ± 0.1% FS is metabolized into water and carbon dioxide, which is an inexhaustible renewable resource

natural plant fiber is also a renewable resource that meets the requirements of sustainable development. It is the most abundant carbohydrate on the earth. In nature, it can be degraded by microbial decomposition enzymes and ingested as a nutrient source for plants or microorganisms

chitin is the general term of chitin and chitosan, which is abundant in the shells of lower animals, especially arthropods (such as crabs, shrimp, insects, etc.). Chitin fiber is the only cationic natural fiber with positive charge in nature. Chitin biosynthesis in the world reaches tens of billions of tons every year, and its output is second only to natural cellulose. It is the second largest biopolymer resource on the earth

Application of biological packaging materials

in recent years, people use natural biological materials to make packaging raw materials, or extract the raw materials from natural biological materials to make packaging materials, and develop new biological packaging materials. Once these biological packaging materials come out, they show their strong vitality

starch based biological packaging materials

in recent years, the biodegradation of modified starch or soluble degradable plastics has become a hot spot in the research and development of starch based materials. Starch based materials can be used as the packaging of fried fast food, disposable food bags and the outer film of paper packaging

starch based polyvinyl alcohol is a typical representative of starch based packaging materials. It processes starch before film making, that is, it is "disordered and plasticized" or chemically modified in the extruder, adds a certain amount of plasticizer starch, and then blends with polyvinyl alcohol or polyacetic lactone to obtain a transparent film. The starch part in the membrane will even be almost zero biodegradation, and the rest will be degraded during the stacking process. Starch polyvinyl alcohol film has medium gas barrier property, and its mechanical property is worse than that of synthetic polymer film. It can replace low-density polyethylene packaging in disposable food bags. Experiments show that starch based materials do not promote the growth of microorganisms, and bacteria outside the packaging will not penetrate into the packaging, indicating that starch based materials have long-term packaging potential

corn is a delicious and nutritious starch food, which is also widely used in the manufacture of sweeteners and animal feed. With the progress of technology, the sugar in corn is extracted, and through fermentation, distillation and extraction, the basic materials for manufacturing plastics and fibers are obtained. The basic materials are then processed into polylactide (PLA) fine particles with a diameter of only 4.57mm. Finally, these small particles are made into packaging bags, foamed plastics or tableware

application of cellulose synthetic materials

cellulose is a polyhydroxyglucose polymer, which has different functional characteristics after specific physical and chemical modification. It can appear in different forms such as powder, sheet, film, fiber and solution. It has the advantages of low price, degradability and no environmental pollution at the same time. Therefore, the functional materials developed with cellulose are very flexible and widely used

various biodegradable materials synthesized from cellulose have strong reactivity and interaction properties due to many hydroxyl groups on their macromolecular chains. Therefore, the processing technology of these materials is relatively simple, the cost is low, and the processing process is pollution-free; It can be completely degraded by microorganisms; Cellulose material itself is non-toxic and can be widely used. Because cellulose has strong hydrogen bonds between molecules, high degree of orientation and crystallinity, and is insoluble in general solvents, it cannot be directly used to make biodegradable materials, so it must be modified. The modification methods of cellulose mainly include acylation, etherification and oxidation to aldehydes, ketones, acids, etc

the straw board processed from straw has the functions of energy saving, heat preservation, heat insulation, sound insulation, etc., good air permeability, high impact strength, and significantly higher waterproof and seismic resistance than traditional materials; In addition, as a packaging material, the unit mass of straw board is 1/10 of that of paperboard with the same volume, which has obvious advantages

in addition to straw, other straw pulps are also used as the main raw materials in China to develop special cardboard for disposable tableware. Chemical additives are used to optimize the application technology to improve the quality of straw pulp, ensure that the straw pulp is close to the physical properties of tableware paperboard, and the surface is processed for food packaging, so that the finished product has the functions of hot water resistance, no leakage, no layering, oil resistance and heat sealing

protein membrane material

although the membrane made of plant protein is not completely hydrophobic, it has good moisture resistance and oxygen resistance, and can be extruded; Its oxygen resistance is greatly affected by environmental humidity. It can be compounded with lipids during film formation to improve the stability of oxygen resistance, so as to apply and improve the storage of oil-bearing food

wheat gluten film has been used to coat fried peanuts and fried chicken. This film has appropriate oxygen resistance, but it has full permeability to carbon dioxide. It is suitable for fresh products that need respiration, and its permeability to aromatic substances is 1/10 of that of low-density polyethylene film, which is conducive to preserving food flavor

collagen, whey protein and casein are mainly used for membrane preparation. Collagen membrane is an edible protein membrane that is widely used. It has good oxygen resistance under low humidity, so it is widely used as sausage casings; Whey protein film can reduce the permeability of oxygen, and compound coating with diethylene glycol monoglyceride and Frozen Salmon and roasted peanuts can significantly reduce its oxidation rate, and also can migrate water in less breakfast food; The composite film of casein and fat can be applied to the preservation of fresh vegetables, dried fruits and freezing rain, and can reduce water migration and oil oxidation

chitin and Chitosan Composites

the packaging material prepared by processing chitin has good air permeability, water absorption and moisture retention. The material also has good chemical stability, light resistance, drug resistance, oil resistance, organic solution resistance, cold resistance, etc., and its stability is better than that of paper. As chitin comes from biological structural substances, it has strong affinity and biocompatibility with human cells, can be decomposed and absorbed by enzymes in the body, and has no toxicity and side effects on the human body. It can effectively protect the human body from the skin damage caused by micro radiation and heavy metal ions in nature, and can be used in the manufacture of textiles

the preparation of derivatives with unique properties through chemical modification and modification of chitin and chitosan has become an important aspect of application and development in the world today. At present, the high-tech products of marine biomaterials prepared by chitin and its derivatives have been launched continuously in the world, and the applied products have reached more than 500 kinds. The United States, Japan, Italy, Norway, India, South Korea and other countries have successively established chitin chitosan production plants, of which Japan and the United States are the main producing countries and major consumers

other biological packaging materials

British scientists extracted three genes that can produce plastic from bacteria that make biopolymers, and then transferred them to rape plants. After a period of time, a polymer liquid was produced, and then after refining and processing, a kind of vegetable plastic was obtained. This kind of plastic is processed into packaging materials or baby diapers, which can be dissolved by itself after being discarded, without polluting residues. At present, because of the high cost of extracting polymers from microorganisms, it can not be widely used. If the cost can be reduced by expanding the production scale and changing the process, it will be a kind of polymer with great potential

Brazil has developed a new environmental protection material "biological foam", which can replace the existing foam. 70% of the new substances are refined from the oil products of corn, soybean and castor, while the petroleum component accounts for only 30%. Biological foams can be used as light packaging materials, which can be dissolved in nature in less than two years

in China, the development of new biological packaging materials has also achieved some results. The technology of processing deteriorated grain into shockproof and decompression packaging materials has been mastered, which not only finds a way out for China's deteriorated grain, but also successfully explores the way to replace packaging materials. In addition, they can also process bagasse, wheat straw and waste newspapers into various shockproof and decompression packaging materials such as golden yellow, orange yellow and light gray. The test shows that the performance of this material is not better than that of