Nanotechnology and Advanced Materials Central Lab, Regional Center for Food & Feed, Agricultural Research Center, Giza, Egypt; Department of Food and Nutrition, Kyung Hee University, Seoul 02447, Republic of Korea.
School of Bioengineering and Food Technology, Shoolini University, Solan 173229, India; Department of Food Technology and Nutrition, School of Agriculture, Lovely Professional University, Phagwara, Punjab 144411, India.
Int J Biol Macromol. 2023 Jul 1;242(Pt 3):124905. doi: 10.1016/j.ijbiomac.2023.124905. Epub 2023 May 22.
Five natural pigments including water-soluble [butterfly pea (BP), red cabbage (RC), and aronia (AR)] and alcohol-soluble [shikonin (SK) and alizarin (ALZ)] were extracted, characterized, and loaded onto cellulose for preparing pH-sensitive indicators. The indicators were tested for their color response efficiency, gas sensitivity, response to lactic acid, color release, and antioxidant activity. Cellulose-water soluble indicators showed more obvious color changes than alcohol-soluble indicators in lactic acid solution and pH solutions (1-13). All cellulose-pigment indicators exhibited prominent sensitivity to ammonia compared to acidic vapor. Antioxidant activity and release behavior of the indicators were influenced by pigment type and simulants. Kimchi packaging test was carried out using original and alkalized indicators. The alkalized indicators were more effective in showing visible color changes during kimchi storage than the original indicators, and cellulose-ALZ displayed the most distinct color change from violet (fresh kimchi, pH 5.6, acidity 0.45 %) to gray (optimum fermented kimchi, pH 4.7, acidity 0.72 %), and to yellow (over fermented kimchi, pH 3.8, acidity 1.38 %) which followed by BP, AR, RC, SK respectively. The findings of the study suggest that the alkalization method could be used to show noticeable color changes in a narrow pH range for application with acidic foods.
五种天然色素，包括水溶性[蝶豆花（BP）、紫甘蓝（RC）和黑果腺肋花楸（AR）]和醇溶性[紫草素（SK）和茜草素（ALZ）]，被提取、表征，并负载到纤维素上，用于制备 pH 敏感指示剂。这些指示剂的颜色响应效率、气体敏感性、对乳酸的响应、颜色释放和抗氧化活性进行了测试。在乳酸溶液和 pH 溶液（1-13）中，纤维素-水溶性指示剂比醇溶性指示剂表现出更明显的颜色变化。与酸性蒸气相比，所有纤维素-色素指示剂对氨都表现出显著的敏感性。指示剂的抗氧化活性和释放行为受到色素类型和模拟物的影响。使用原始和碱化指示剂进行了泡菜包装测试。在泡菜储存过程中，碱化指示剂比原始指示剂更有效地显示出可见的颜色变化，而纤维素-ALZ 则显示出最明显的颜色变化，从紫色（新鲜泡菜，pH 5.6，酸度 0.45%）变为灰色（最佳发酵泡菜，pH 4.7，酸度 0.72%），再变为黄色（过度发酵泡菜，pH 3.8，酸度 1.38%），其次是 BP、AR、RC、SK。研究结果表明，碱化方法可用于在较窄的 pH 范围内显示明显的颜色变化，可应用于酸性食品。
