海藻酸钠膜的研制及其在鲜切莴苣保鲜中的应用

摘  要

本论文以海藻酸钠作为可食性膜的主要成膜物质，添加增塑剂制成海藻酸钠复合膜并用交联剂改变其性能。通过测定其物理性能(包括抗拉强度、断裂伸长率、水蒸气透过率和透光率)来确定海藻酸钠的浓度；增塑剂的种类和浓度以及交联剂的种类和浓度。再将所制成的海藻酸钠复合膜用来保鲜鲜切莴苣，通过测定鲜切莴苣在贮藏过程中感官评价、失重率、维生素C、呼吸强度和菌落总数的变化，来研究海藻酸钠复合膜对鲜切莴苣的保鲜效果。
结果表明：采用浓度为3％的海藻酸钠和浓度为0.2％的单甘脂制成的海藻酸钠复合膜具有较好的物理性能。海藻酸钠复合膜经过4％的氯化钙交联15min后抗拉强度增强。经海藻酸钠复合膜包装的鲜切莴苣呼吸作用得到了明显的抑制，失重率、褐变度等指标的变化速度均低于未包装的，能保鲜4天，比未包装的延长保鲜期2天。

关键词：海藻酸钠，复合膜，鲜切莴苣

 
ABSTRACT

Sodium alginate was selected as the basic material to form the edible film in this paper. Plasticizers were added to the sodium alginate to form compound film, and the compound film was treated by cross-linker to improve its properties. the concentration of sodium alginate, together with the type and consistence of plasticizers and cross-linker, was determined by measuring the physical properties (including the tensile strength , elongation at break, water vapor transmission and transmission rate) of the film. Then the alginate compound film was used to preserve fresh-cut lettuce. The effect of the compound film on the preservation of fresh-cut lettuce was studied through measuring the change of sensory evaluation, weight loss, vitamin C, respiration rate and total number of microorganism of fresh-cut lettuce during storage.
The results showed that the sodium alginate composite film made up by 3% sodium alginate and 0.2% monoglycerides had better physical properties. The 15 minutes treatment with 4% calcium chloride on the composite film could increase the tensile strength of the film. In the course of Storage, the respiration of the fresh-cut lettuce packaged with the compound film was inhabited. The change of the quality index, such as weight loss and browning of fresh-cut lettuce were lower than the blank group. The fresh-cut lettuce could be kept for 4 days, 2 days longer than the blank.

Keywords:sodium alginate, compound film, fresh-cut lettuce

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