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Konjac Glucomannan/Acrylamide Modification Film In The Research And Application Of LuGan Preservation

Posted on:2011-08-22Degree:MasterType:Thesis
Country:ChinaCandidate:S L ChenFull Text:PDF
GTID:2131330332469071Subject:Food processing and security
Abstract/Summary:PDF Full Text Request
A long time,picking fruit and vegetable production and more emphasis on its cultivation technique before,but ignored the post-fresh storage. China's annual fruits and vegetables during storage and transport of the loss rate as high as 20% to 30%, the total value of the loss of nearly 800 billion yuan, while in developed countries, the loss rate of only 1.7% to 5.0%, showing that our preservation technology solved and improvement. Fresh fruits and vegetables currently used mainly plastic wrap plastic film, but it has its own shortcomings, not only can not be natural degradation, but also bring a range of safety to human health risks. Faced with this reality, people continue to develop and launch a paper packaging products and biodegradable plastic materials, hoping to replace the plastic film, but in the end because of its high cost, expensive and not conducive to the promotion a lot. Therefore, the search for a good performance with plastic, which is easy to be biodegradable, no health threat to people and the preservation of low-cost materials,has been the focus of people and hot sports in the long-term. Study found that polysaccharide film has the advantages of easily biodegradable, good performance, environmental health and so on, is a good substitute for plastic wrap, increasing people's attention. The use of selected konjac glucomannan(Konjac glucomannan, referred to KGM) as basic material and compound acrylamide(Acrylamide)as modified materials, development of KGM/acrylamide modified film,discussed the KGM/acrylamide mass ratio, glycerol content, pH, reaction time, potassium permanganate concentration of different factors on konjac glucomannan/acrylamide modified film characteristics by the tensile strength, elongation at break of Mechanical Properties of Films,to determine the best modified film forming,the optimum conditions for film formation process and parameters of the key technologies to provide a reference; and study the modification of the film obtained Citrus Preservation of practical application,the study results are as follows:1 Compared with the film made by after purification of konjac glucomannan powder not,the former has the merits of higher tensile strength, smaller thickness, elongation at break larger, more bright color, and so on.This ia related to the increased interaction force between purified konjac glucomannan hydrogen bonds. Early experiments showed that the film, film tension, water solubility, viscosity of purified konjac glucomannan than those without pre-purification of konjac glucomannan were improved, which is purified to remove the Konjac polysaccharide surface components of non-glucomannan results.2 Konjac glucomannan combined with acrylamide, the film performance over a single films of konjac glucomannan has been greatly improved, KGM/acrylamide mass ratio, glycerol content, pH, reaction time, concentration of potassium permanganate have a certain extent effects on tensile strength, elongation properties of the film a certain extent. Factors affecting the film performance analysis of orthogonal test, obtained a comprehensive analysis and evaluationthe of modified layer, the orthogonal analysis of test results to determine the optimum conditions of film system that makes the best system available film conditions, which is the KGM/acrylamide ratio of 1:1, the amount of glycerol 0.45mL, pH9.5, reaction time 1h, potassium permanganate concentration of 1.0×10-3mol·L-1.3 KGM modified film for the preservation of citrus and used unmodified KGM film as a control, observed the practical effect of KGM modified film. The results showed that: Modification of film treatment can effectively reduce the citrus physiological activity during storage, the biofilm permeability can regulate gas exchange inside and outside of the film and effective to prevent the anaerobic respiration of citrus. In the storage period, the modified film can significantly reduce the weight loss and respiration of citrus, and the total loss of the nutrients such as Vc and total acid can be maintained at a lower level. Relative to the control group was 10% rot rate, the modified film can control the last rot rate of citrus at low 4%, with good preservation effect.After film processing, citrus peel in the PPO, POD activity was significantly inhibited, the effective mitigation of the pericarp browning. Control group of citrus peel PPO, POD activity increased faster, more serious skin color brown. In the first 60 days, PPO activity of the control group is increased by 22.8% than the first day, POD activity increased by 51.7%, the incidence and decay rate of citrus fruit were also increased substantially in this period. Relative to control group,the citrus PPO, POD activity of film treatment changes in relatively gentle, the controlled grop film processing citrus PPO activity of the first 60 days increased by 9% than the first day, POD activity increased by 37.9%, the modified film treatment of Lo Kom PPO activity in the first 60 days than the first day of an increase of only 4.5%, POD activity increased by 25.5%. Therefore, the modified film treatment of citrus PPO, POD is relatively small increase and its PPO, POD activity were well inhibited, reducing the citrus browning during storage,slow down the browning of citrus and related self-generated product of the amount of free radicals, control premature browning of citrus.After film treatment of citrus, the SOD activity decreased throughout the storage period of less able to maintain relatively stable basic level.But the increased citrus SOD activity of control group was first quickly, then declined sharply, especially in the first 40 days to 60 days, dropping by surge more than 22%. So after film treatment of citrus, SOD activity has also been a lot of inhibition, reducing the content of the free radicals that were produced by itself and related with its browning and aging, reducing the citrus browning rate during storage, incidence, rotting rate,and significantly improved the appearance of citrus quality.KGM modified film and control film results in the Citrus Preservation much better than the control group, but the overall effect of KGM modified film is superior to the unmodified control film, indicating that the combination of KGM and acrylamide can optimize KGM film performance and practical effect. Especially in the fruit disease, reduce the rate of fruit decay and reduce the fruit during respiration and other aspects of use of effects, KGM modified film is significantly better than the control film and is the ideal alternative to plastic film products, the potential commercial value and economic benefits are substantial, broad application prospects.
Keywords/Search Tags:Konjac glucomannan, Acrylamide, modified film, Citrus, fres
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