改性花青素涂覆聚丙烯新鲜度指示膜的制备与研究

以乙酸为酰化剂对玫瑰茄花青素改性处理制得新鲜度指示剂,选用聚乙烯醇(PVA)为基液,与改性花青素共混制得新鲜度指示液,以聚丙烯(PP)为基膜采用旋涂法制备食品新鲜度指示膜。对改性花青素进行红外光谱及紫外-可见光光谱分析,对指示膜pH响应性、热稳定性和光照稳定性进行了研究。结果表明,红外光谱显示玫瑰茄花青素成功引入酰基;紫外-可见光谱显示改性后的花青素溶液在可见光区域最大吸收峰下的吸光度突变区间由pH值2~3迁移到pH值3~4;指示膜pH响应测试显示随着pH值升高指示膜由红变浅粉再变绿;所制备改性花青素指示膜在光照和不同温度下的颜色稳定性均高于未改性花青素指示膜。

Preparation and study of modified roselle anthocyanin coated polypropylene freshness indicator film

Freshness indicator was prepared by chemical acylation with acetic acid and roselle anthocyanins.The freshness indicator solution was prepared by blending polyvinyl alcohol (PVA) with modified anthocyanins.The film was prepared by coating the indicator solution on the surface of PP with spin coating method.The modified anthocyanins were analyzed by FT-IR and UV-Vis spectra,and the pH response,thermal stability and light stability of the indicator film were studied.The FT-IR showed that the acyl group was successfully introduced into roselle anthocyanins.The UV-Vis spectrum showed that the absorbance mutation range of the modified anthocyanin solution under the maximum absorption peak in the visible light region moved from pH 2-3 to pH 3-4.The pH response test of the indicator film showed that the indicator film changed from red to light pink and then to green as the pH value increased.The color stability of modified anthocyanin indicator film was higher than that of unmodified anthocyanin indicator film under light and different temperature.