食品包装用凝胶型二氧化碳指示标签研究

在前期研究的基础上,以质量分数为5%且质量之比为3：2的甲基红和溴百里酚蓝混合溶液为二氧化碳指示剂,甲基纤维素和甘油为主要成胶材料,制备了凝胶型二氧化碳含量指示标签。研究了凝胶与指示溶液在变色过程中的吻合度,及运用该凝胶制备指示膜的最佳配方。研究结果表明：适量浓度甲基纤维素制备的凝胶与指示溶液变色吻合度较高,对指示剂颜色变化无影响,可作为指示标签的主要成膜材料;结合甲基纤维素凝胶的黏度、变色响应时间、挂壁百分比及流延性能等指标,确定出成胶的最适甲基纤维素添加质量分数范围为1.6%～1.8%;运用甲基纤维素质量分数为1.6%～1.8%凝胶制备指示膜的过程中,适宜的甘油添加量可以使成膜表面光滑、平整,并有利于水分的保持;最终确定指示标签的最佳制备条件为甲基纤维素的添加质量分数为1.8%,甘油的添加体积分数为4%。

Study on Gel-Type Carbon Dioxide Indicator Label Used in Food Packaging

On the basis of previous research, the gel-type carbon dioxide indicator label was studied. The indicator label consists of carbon dioxide indicator solution and gelling solvent. The mass concentration of the indicator solution was 5% and the indicator was composed of 3/5 methyl red and 2/5 bromothymol blue. Methyl cellulose and glycerol were the primary materials to make the gel. The goodness-of-fit during the color changing process of the gel and the indicating liquid were studied. Then the optimum formulation for the indicator film was studied by using the gel. Results show that: the gel made by appropriate concentration of methyl cellulose had a high goodness-of-fit with color change of indicator solution. As it had no effect on color change of indicator solution, so it could be used as the main film forming material to develop the indicator label. Considering overall indexes of viscosity, response time of color change, the hanging wall percentage and casting performance, the optimum additive mass fraction of methylcellulose was got as being 1.6%~1.8% to make the indicator gel. During the process of making the indicator film by using the gel which contained 1.6~1.8 g/100 g methylcellulose, it was found that appropriate additive amount of glycerol could make the membrane smooth and flat, while it was good for keeping moisture. Finally the optimum condition of making the label was got: the adding mass fraction of methyl cellulose was 1.8% and the adding volume fraction of glycerol was 4%.