Study On The Property And Application Of The Edible Membrane Of Konjac Glucomannan/Chitosan Blends

With the enhancement of the healthy consciousness and the concept of environmental protection, the requirements of people on the materials for food preservation are more and more high. In the preservation of fruits and vegetables, the plastic film is mainly used at present. The plastic film not only does some harm to people's health,but also achieves no natural degradation and causes environmental pollution. With the development of science and technology, researchers have introduced the film products with natural degradation, but their high costs are difficult to be accepted by producers and consumers and unfavorable to their popularization and application. Hence the research turns to focus on seeking a kind of packing materials, which not only has good performances but also can achieve natural degradation, and won't harm to the health of human. In recent years, the film of polysaccharide is considered to be the replacement of the materials of plastic wrap, because it bears many advantages: it is easy to be naturally degradable, its performances are good, the cost of the raw materials is lower, etc. This study here chose konjac glucomannan (KGM for short) as the material and chitosan (CTS) with good biocompatibility and the function of bacteriostasis as the blend, developed the edible membrane of KGM / CTS blends, and then by taking its tensile strength, elongation at break, performance of oxygen resistance and water vapor permeability as the detecting index, explored the various influencing factors on its performances, such as the ratio of KGM/CTS, the dosage of glycerin, the pH value of liquid membrane, the temperature of drying, the time of drying and so on. And on this basis, the study further confirmed the optimum technological conditions to film the compound membrane, and then probed into its practical effects on the preservation of loquat. The results of this research were as follows:1. Compared with the compound membrane made by the unpurified sample KGM, the one made by purified sample KGM was somewhat improved in its various performances—its tensile strength increased by more than twice, and the properties of antioxidant and resistance of water also improved to some extent. This was mainly due to the KGM purification process, which made the force between KGM molecules enhance so that the degree of integration between molecules improved. Thus its various performances were improved to some extent.2. The study here showed that, such various factors as the dosage of KGM, the ratio of KGM/CTS, the dosage of glycerin, the pH value of liquid membrane, the temperature of drying, the time of drying and so on, had a significant influence on the mechanical properties and other performances of the compound membrane. By analyzing the results of orthogonal tests and by comprehensively evaluating all kinds of performances of the compound membrane, the optimum technological conditions of the edible compound membrane were finally confirmed: the ratio of KGM/CTS was 3:2, the dosage of Glycerin was 0.4 ml, the pH value was7.5, the time of drying was 3h, and the temperature of drying was65℃.3. By adopting the edible compound membrane to preserve loquat to test its practical effects, the result of study also showed that the physiological and biochemical activity of loquat could be somewhat reduced during its storage and the practical effects of preservation were better. At the end of the storage, the compound membrane was found to significantly reduce the percentage of weight loss of loquat, and delay the emergence of the peak breathing, and maintain the losses of total sugar, total acid and other nutrients at an appropriate level. After the processing with the compound membrane, the activity of various enzymes in the skin of loquat had a somewhat drop; for example, that of PPO and SOD was better controlled, and the browning level of loquat in storage was reduced. Thus the quality of loquat was improved significantly and then its commercial value. In short, the effects of the preservation with the compound membrane were better than with the plastic film. The compound membrane bore edibility and did no harm to the environment and health of human, so it turned out to have a broad prospect.