壳聚糖复合膜的制备及其性能研究(可编辑)

摘要

本文的目的是采用涂布法以聚乙烯醇(PVA)膜作为基膜制备壳聚糖复合膜, 以得到具有高阻隔性、较好力学性能、可降解性和抗菌性的食品包装材料,用乌氏粘度计测定壳聚糖的相对黏均分子质量。所用 3 种壳聚糖的相对黏均分

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子质量分别为:4.68×10 、4.77×10 、6.68×10 。

比较抑菌圈法、比浊法、稀释平板计数法发现,比浊法结合稀释平板计数法用

于空白组与实验组的活菌计数,可以更准确地显示壳聚糖的抑菌效果。壳聚糖溶液

浓度为 0.01%的 LB 培养液在培养过程中出现絮状沉淀,而高浓度(0.1%)和空白实

验则不出现。这一有趣现象未见文献报导。相对分子质量大的壳聚糖的抑菌作用较

强。太低浓度的壳聚糖溶液,如 0.01%浓度,对两种细菌的抑菌效果不理想。对 E. coli

抑菌活性昀好的壳聚糖溶液浓度是 0.05%;而对 S. aureus 抑菌活性昀好的浓度则是

0.025%。

合成的两种壳聚糖衍生物样品(PCS、TMC)为白色絮状,都能溶于中性水。

浓度为 0.1%的 PCS 和 TMC 溶液都能有效抑制 E. coli 的生长。壳聚糖衍生物对细菌

的抑菌活性有一定的选择性。TMC 对 E. coli 菌比对 S. aureus 菌具有更好的抑菌效

果。

以 PVA 膜作为基材,采用涂布法制备了 PVA/壳聚糖复合膜。用万能材料试验机

测定复合膜的力学性能。复合膜的弹性模量随所用壳聚糖浓度的增大而增大。复合

膜的断裂伸长率和抗拉强度比 PVA 膜略微减小。

用透湿仪测定了复合膜的水蒸汽透过系数。各类复合膜的水蒸汽透过系数略高

于 PVA 膜。用 CS-1 和 CS-2 制得的复合膜的水蒸汽透过系数随壳聚糖浓度的增大而

增大;然而涂布 CS-3 的复合膜的水蒸汽透过系数却随着壳聚糖浓度的增大而减小。

复合膜的水蒸汽透过系数受环境相对湿度影响较大。用透氧仪测定了复合膜的氧气

透过系数,涂布壳聚糖可以提高 PVA 膜对 O 阻隔性能。

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采用 QB/T 2591-2003 标准方法评价了复合膜对 E. coli 和 S. aureus抑菌效果。复

合膜对受试菌均有较好的抑菌效果。用三种壳聚糖制得的复合膜对受试菌的抑菌率

均随壳聚糖浓度的增大而增大。其中, CS-3-2%膜的抑菌活性昀佳,对受试菌的抑

I

菌率达到 99%。

壳聚糖复合膜结合了 PVA 膜和壳聚糖的优点。复合膜既保持了 PVA 膜的高阻隔

性、可降解性和较好力学性能,又具备了壳聚糖抗菌性的优点。

关键词:活性包装,壳聚糖,聚乙烯醇膜,抗菌活性,水蒸气透过系数,氧气透过

系数II

Abstract

The objective of this study was to obtain a complex active package film, prepared

by coating chitosan on polyvinyl alcohol film, with properties of high-resistance,

well-mechanics, biodegradation and antimicrobial

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Relative molecular weight of three kinds chitosan used in this study were 4.68×10 ,

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4.77×10 and 6.68×10 respectively, tested by Ubbelohde viscometerNephelometery combine with dilution-plate method showed the antibacterial

activity of chitosan accurately, comparing whit inhibition zone and nephelometeryFlocculent precipitate occurred in LB with 0.01% chitosan during cultivation. This

interesting phenomenon was not reported in literature. Chitosan showed high

antibacterial activity against E. coli and S. aureus, with higher molecular weight showed

better antibacterial activity. While 0.01% concentration of chitosan showed no good

antibacterial. The best antibacterial condition of chitosan was 0.05% concentration

against E. coli, and 0.025% concentration against S. aureus PCS and TMC synthesised were white floccus, and had good solubility in neutral water. Antibacterial activity of PCS and TMC with 0.1% concentration against E. coli is

well. Antibacterial activity of PCS and TMC had selectivity. Antibacterial activity of

TMC against E. coli was better than against S. aureus

Complex film was prepared by coating chitosan on polyvinyl alcohol