| This paper forecasts the stability and temperature in the compound fine structure of the konjac glucomannan, soybean protein isolate and carrageenan by assistants of computer molecular simulation. According to both computer and Mono-factor experiment results, konjac glucomannan, soybean protein isolate and carrageenan have been chosen as the raw materials. By adding emulsifier, plasticizor, reinforce agent and bacteriostasis factor, tensile strength and water vapor permeability have been studied. Optimum technological parameters of KGM/bio-polymer composite film and application in fresh-cut lettuce preservation have been explored. The main results are as follows:1.Based on results of computer molecular simulation : we found that when konjac glucomannan, soybean protein isolate and carrageenan mixed, they entangled and interacted closely, finally they formatted a stable structure; By the analysis of hydrogen bonds, it is showed that the amount of hydrogen bonds increased significantly after the konjac glucomannan, soybean protein isolate and carrageenan blended,and reached a max amount at the temperature of 75℃.2. Results of the Mono-factor experiment showed that: optimum technological parameters are as follows: the membrane material ratio was 1:1:1, membrane material concentration was 0.75%, blending temperature was 75℃, the glycerol concentration was 0.7%, Monoglyceride concentration was 0.15%, stearic acid concentration was 0.2%, pH was 9.0, the membrane would have a higher tensile strength and better water resistance.3. Including the participants as pH, membrane material concentration and glycerol concentration factor, tensile strength as the main indicator, we used the quadratic regression rotation to design tensile strength of the model for the objective function: YTs=28.27561-0.97593X2+3.153X3-0.92514X12+1.37375X1X3 Through single factor analysis, we found that: pH>glycerol concentration> membrane material concentration.4. Verification test has been done under the most optimal tensile strength. The result showed that the predictive value was in line with the actual value. Through the contrast of a single membrane glucomannan, the results indicated that: the optimization which used the tensile strength as index was improved significantly when compared with single glucomannan membrane.5. The experiment results showed that, E. coli and Penicillium were more inhibited significantly for KGM / bio-polymer composite membrane; KGM / bio-polymer composite membrane had stronger geographical degradation. After 60 days'geographical degradation, the weight loss was up to 63.46%.6.In order to enhance the KGM / bio-polymer composite membrane preservation of fresh-cut lettuce, we used the pH, the concentration of membrane material concentration and the concentration of glycerol as the participants, and used steam coefficient as an index to optimize the test through the coefficient of water vapor permeability in the objective function of the model:YWVP=11.50153-1.11266X1-1.47155X2+1.47599X12+1.71110X22-0.9425X1X2 Through a single factor analysis, the water vapor permeability impaction we have got was: glycerol concentration > membrane material concentration > pH. We used Lingo7.0 to obtain the mathematical model, when the coefficient of water vapor was 10.7706 g·mm/m2·day·KPa, pH was 9.5, Glycerol concentration was 0.85%, membrane material concentration was 0.775%, the formulation can obtain the minimum.7. We explicated the optimal formulation of the composite membrane system into fresh-cut lettuce, the results showed that: KGM / bio-polymer film packaging group showed a good storage characteristics after 21days'storage at 4℃~ 6℃, prevented the loss of nutrients, maintained a basic quality lettuce, and effectively curbed browning. |
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