Chitosan, also known as chitosan, is obtained by the deacetylation of chitin, which is widely found in nature, with the chemical name polyglucosamine (1-4) -2-amino-BD glucose . Since 1859, the French Rouget first got chitosan, this natural polymer biological properties and compatibility, blood compatibility, safety, microbial degradation and other excellent performance has been widespread concern in all walks of life, in Significant progress has been made in applied research in many fields such as medicine, foodstuffs, chemicals, cosmetics, water treatment, metal extraction and recovery, biochemical and biomedical engineering. For patients, chitosan hypolipidemic, hypoglycemic effects have been reported.
Degree of deacetylation
The degree of deacetylation (DD) determines the amount of amino group (NH2) in the macromolecular chain, and the DD increases. Due to the protonation of the amine group, the charged groups of the chitosan in the dilute acid solution increase. The charge density of the polyelectrolyte Increase, the result will inevitably lead to changes in its structure, properties and performance, the nature of the research so far have neglected the DD value of the impact of equation equation. VANDUM et al. Studied the effect of different ionic strengths on the molecular size and viscosity of chitosan in dilute solutions. The results show that different ionic strength will change the degree of swelling of random clumps and then change the molecular size and intrinsic viscosity. The determination of the constant of MARK-HOUWINK equation for different D.D chitosan shows that the K and A values change with the D.D value. Thus, the constants K, A of MARK-HOUWINK equation are regularly dependent on the degree of deacetylation of chitosan, and at the same molecular weight, with the increase of degree of deacetylation, the molecular weight of chitosan in dilute solution, the intrinsic viscosity And expansion factor increased, while the ratio of properties and steric factors decreased with the increase of degree of deacetylation. As a result, the average molecular weight of any chitosan sample within the applicable range can be calculated by comparatively simple intrinsic viscosity measurement.
1, cosmetics chitosan
Cosmetics for chitosan has a good moisture absorption, moisturizing, conditioning, antibacterial and other functions; for moisturizing cream, shower gel, facial cleanser, mousse, high-grade cream, lotion, gel cosmetics, etc .; effective make up the general shell Defects of glycans.
2, flocculant special chitosan
Chitosan and its derivatives are good flocculation, clarification. As the clarifying agent of the beverage, the suspended matter can be rapidly flocculated and precipitated naturally to increase the yield of the original liquid; in the traditional Chinese medicine extract, the macromolecule protein, tannic acid and pectin can be conveniently removed by the chitosan solution and refined The purity of the Chinese medicine effective ingredients; the use of chitosan adsorption, water purification has a good effect.
3, tobacco (tobacco plastic) special chitosan
The product can be uniformly mixed with cut tobacco, and can adhere to the tobacco surface, can enhance the tensile strength, water resistance, bursting resistance, processing is not easy to break, suitable for modern high-speed cigarette machine; the tobacco additive allows the combustion of cigarette branch Performance significantly enhanced, with the role of tobacco tar and nicotine levels to reduce the smoke airer gas, reduce the harmful substances in the flue gas, smoking improved, the aroma revealed; also be able to effectively inhibit tobacco mildew and prolong the preservation of tobacco time.
Chitosan and its derivatives have good antibacterial activity, can inhibit the growth of some fungi, bacteria, and viruses. As of 2013, three possible mechanisms are considered: one is the polycation of chitosan, which is easy to function as a negatively charged group on the surface of the fungal cell to change the fluidity and permeability of the cell membrane of the pathogen; the other is to interfere with the DNA Of the replication and transcription; third is to block the pathogen metabolism. Since 2010, many researchers have proposed the idea that chitosan can achieve antibacterial effect by inducing pathogenesis-related proteins, accumulating secondary metabolites and signaling.
Fruit and vegetable preservatives
The main purpose of preservation of fruits and vegetables is to maintain the fruits and vegetables until the shelf life after picking, to maintain normal quality, taste, nutrients and appearance, improve their value of the goods. With chitosan coating preservation, the membrane permeability, water resistance, can increase the penetration resistance of a variety of gas molecules, the formation of a micro-atmosphere, is the organization of fruits and vegetables increase the carbon dioxide content, oxygen Reduce the content, inhibit the respiratory metabolism of fruits and vegetables and water loss, reduce fruit and vegetable tissue and structural aging, thereby effectively extending the post-harvest life of fruits and vegetables.
Meat products due to contain high levels of unsaturated fatty compounds easily oxidized meat deteriorated, thereby reducing the shelf life of meat products and savage the flavor of meat products. Darmadji and Izumimoto studied the oxidative stability of beef treated with chitosan. As a result, it was found that adding 1% of chitosan and storing at 4 ° C for 3 days reduced the thiobarbituric acid in beef by 70%. Shahidi reported that N, O-carboxymethyl chitosan (NOOC) and its lactate, pyrrolidine carboxylate are very effective in inhibiting the oxidation of cooked meat, and the flavor of cooked meat almost does not change after 9 days of storage. He pointed out that the NOX and the aforementioned chitosan derivatives had an inhibitory oxidation effect of 69.9%, 43.4% and 66.3% at (500-3000) x 10-6, respectively. This mechanism of inhibition of oxidation is related to free iron ions and chitosan in the meat. When the meat is heat-treated, free ferric ions are released from the hemoglobin of the meat and chelate with the chitosan to form chelates, thereby inhibiting the catalytic activity of iron ions.
Health food additives
Chitosan is hardly digested by the human body for gastrointestinal absorption, and when they are taken into the body, they can form complexes with lipid compounds such as triglycerides, fatty acids, bile acids and cholesterol corresponding to many times their own mass, Complex is not acid hydrolysis, is not absorbed by the digestive system, thus hindering the body to absorb such substances, make it through the intestine and excreted. Therefore, chitosan can reduce fat, reduce food heat, can be used as health food additives. Agullo other studies have shown that shell two, triose not only has a very refreshing sweetness and blood pressure, eliminate fatty liver, lower cholesterol and enhance immunity function, but also has the ability to improve the water retention and moisture regulation of food can be used as Diabetes and obesity health food additives.
Chitosan has chelate adsorption to many substances. The amino group and the hydroxyl group adjacent to amino group in the molecule can form stable chelate with many metal ions (such as Hg2 +, Ni2 +, Cu2 +, Pb2 +, CA2 +, Ag +, etc.) , For the treatment of heavy metal wastewater, tap water purification and separation of metal ions in hydrometallurgy and so on. Japan is the earliest use of chitosan wastewater treatment countries, annual consumption of 500 tons; the US Environmental Protection Agency has also approved the use of chitosan for drinking water purification. In addition, chitosan can adsorb dyes, proteins, amino acids, nucleic acids, enzymes and halogens through complexation and ion exchange, and can be used for the treatment of dye wastewater, printing and dyeing wastewater and food industry wastewater to purify the environment and protect human health.