花青素-明胶/聚乙烯醇-淀粉复合膜制备与表征

目的 制备花青素明胶/聚乙烯醇淀粉双层复合膜,以期提高花青素单层膜的综合性能.方法 采用流延法分别制备紫薯、紫甘蓝、黑米、黑枸杞、玫瑰、玫瑰茄等6种花青素明胶/聚乙烯醇淀粉双层复合膜,并对比研究膜层的微观组织结构、含水率、力学性能及光学性能.结果 从红外光谱图中可以看出,双层复合膜分子结构没有出现新的特征峰,双层膜结合方式为物理结合,没有新的结构生成,且除紫甘蓝明胶/聚乙烯醇淀粉双层复合膜外,其余复合膜均存在明显的分层界线,2层结合处膜层结构均匀致密,结合良好.不同双层膜的含水率差异显著,而双层复合膜比花青素单层膜的含水率明显降低,不同双层膜的拉伸强度和断裂伸长率差异不显著,与单层花青素明胶复合膜相比,双层复合膜的拉伸强度和断裂伸长率大幅增加,其中紫薯双层膜的拉伸强度增加了75％,断裂伸长率增加了22.9％;所有双层复合膜的透光率相差不大,均在80％以上;与花青素明胶单层膜相比,双层膜的雾度增加了20％左右.结论 制备的双层膜改善了单层膜的力学性能,提高了花青素明胶单层膜的综合性能.

Preparation and Characterization of Anthocyanin-Gelatin/Polyvinyl-Alcohol-Atarch Bilayer Composite Film

The work aims to prepare anthocyanin gelatin/polyvinyl alcohol starch bilayer composite film, so as to improve the comprehensive performance of anthocyanin monolayer film. Six kinds of anthocyanin gelatin/polyvinyl alcohol starch bilayer composite films were prepared by layer-by-layer stretch film technology with purple potato, purple cabbage, black rice, black wolfberry, rose and roselle. Then, the microstructure, moisture content, mechanical properties and optical properties of these films were compared and studied. From the infrared spectroscopy, the molecular structure of the material in the bilayer composite film was mainly the intermolecular force, and no new structure was generated. Except the purple cabbage gelatin/polyvinyl alcohol starch bilayer composite film, the other composite films hadobvious delamination boundary, but the film structure at the junction of the two layers was uniform and compact, with good binding effect. The moisture content of different bilayer films was significantly different, while the moisture content of bilayer composite film was significantly lower than that of anthocyanin monolayer film. There was no significant difference in tensile strength and elongation at break among different bilayer films. Compared with the monolayer anthocyanin gelatin composite film, the tensile strength and elongation at break of the bilayer composite film greatly increased, among which the tensile strength increased by 75% and elongation at break of the purple potato bilayer film increased by 22.9%. The light transmittance of all the bilayer composite films hadlittle difference, all of which were above 80%. The haze of bilayer film increased by about 20% compared with anthocyanin gelatin monolayer film. The prepared bilayer film improves the mechanical properties of monolayer film and enhances the comprehensive properties of anthocyanin gelatin monolayer film.