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Antibacterial enzyme modified soy protein isolate membrane preparation and properties of

Author: DuHuiYun
Tutor: ZhaoShouJing
School: Jilin University
Course: Fermentation Engineering
Keywords: Enzymatic modification Soy protein isolate Mechanical behavior Antibacterial properties Edible films
CLC: TS201.2
Type: Master's thesis
Year: 2011
Downloads: 182
Quote: 0
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Abstract

Preparation of soy protein isolate edible film is more commonly used natural polymer substances. However, soy protein isolate larger molecules, complex structure, mechanical properties more environmentally sensitive, easy to breed bacteria and fungi, shelf life is shorter shortcomings limit its widespread application. By enzymatic modification of soy protein, increase its intramolecular or intermolecular crosslinking, protein film properties can be improved. The natural antimicrobial agent is added to the soy protein isolate membrane will not affect the consumption, but also in food and effectively inhibit microbial growth and reproduction of the membrane surface or directly to kill, inhibit the microorganisms can be achieved, extending the shelf life of food purposes. In this paper, soy protein isolate as film substrate by the enzyme modified soy protein isolate and adding natural antibacterial agent, enzyme modified soy protein isolate research antibacterial membrane preparation process and performance, developed with excellent mechanical properties and antibacterial effects The composite membrane of the main research work and results are as follows: (1) with papain, trypsin, alkaline protease and modified soy protein isolate, the modified enzyme of the membrane thickness, tensile strength, elongation at break, water vapor permeability and other properties. Research shows that with the increasing concentration of the enzyme modified film thickness increases first and then decreases; papain and alkaline protease enzyme modified membrane tensile strength with increasing concentration increased, but modified trypsin film first and then decreases; elongation enzyme concentration increases with decreasing; transmittance with the enzyme concentration first increases and then decreases; protease concentration of 5.0U / g, the membrane water vapor transmission rate are minimum, trypsin modified membrane has a low water vapor permeability; microscopic observations available enzyme-modified membrane surface of the ridge, the membrane surface is more uniform and compact, trypsin modified membrane particularly evident. (2) Study of the inhibition zone using chitosan, lysozyme and antibacterial properties of oregano oil. Escherichia coli and Staphylococcus aureus, the double dilution method using chitosan, lysozyme and oregano oil the minimum inhibitory concentration. The same concentration of chitosan against Staphylococcus aureus inhibition zone diameter slightly larger than the formation of Escherichia coli. Lysozyme and oregano oil on Escherichia coli and Staphylococcus aureus inhibitory effect gradually increased with increasing concentration. The same concentrations of lysozyme and oregano oil on the formation of Staphylococcus aureus inhibition zone diameter greater than E. coli. (3) Research chitosan, lysozyme and oregano oil, soy protein isolate membrane of Escherichia coli and Staphylococcus aureus antibacterial properties. Chitosan, lysozyme and oregano oil, soy protein isolate membranes of bacteria are inhibited, and with the film medium with the increase, antibacterial capacity enhancement. Inhibitory effect compared to the inhibitory effect on E. coli: oregano oil gt; chitosan gt; lysozyme; against Staphylococcus aureus inhibition effect: oregano oil gt; chitosan gt; lysozyme. (4) Research chitosan, lysozyme and oregano oil, soy protein isolate membrane yeast and Aspergillus niger antibacterial properties. Chitosan, lysozyme and oregano oil, soy protein isolate membrane yeast and Aspergillus niger was inhibited, as the film was added to increase the amount of antimicrobial capacity enhancement. Inhibitory effect compared to the inhibitory effect on yeast: chitosan gt; oregano oil gt; lysozyme; inhibitory effect on Aspergillus niger: oregano oil gt; chitosan gt; lysozyme. (5) by a single factor tests to determine the film's technical conditions suitable soybean protein concentration of 4%, the suitable concentration of 1% glycerol, suitable concentration of trypsin 4U / g, oregano oil suitable concentration of 0.4%. optimum drying temperature is 55 ℃. (6) orthogonal test, to get to the tensile strength and elongation at break of indicators optimum conditions. The tensile strength, the optimum process conditions are: soybean protein concentration of 4% glycerol concentration of 1% trypsin concentration of 5U / g, oregano oil concentration was 0.4%, the drying temperature was 55 ℃. On the elongation at break, optimum conditions are: soy protein isolate concentration of 4%, glycerol concentration of 1% trypsin concentration 4U / g, oregano oil concentration of 0.4%, the drying temperature is 55 ℃.

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