Abstract A pH-sensitive dye-based freshness indicator system was prepared, and visible color changes based on the production of volatile acids and CO2 during kimchi storage were monitored. During fermentation, the pH of the kimchi, which was initially 5.4, decreased to moderate values of 4.2–4.4, and reached 4.0 at the end of fermentation. Based on pH and acidity, three fermentation stages were identified. Good correlation between the pH and acidity was observed. The highest CO2 concentration (60 %) and organic acid content (80 mg%) were observed during the optimum fermentation stage. Color changes of the freshness indicator accurately tracked an increase in CO2 concentration in the package headspace. The tested indicators all showed visible color changes with the fermentation stages of kimchi, and the values were significantly correlated with the CO2 concentration, pH, and acidity. Higher TCD values observed between the stages had a significant correlation with visible color changes. The storage, survey, and migration test results indicated that the dye did not migrate into the food materials and is safe for use inside the food package. Results of this study will be useful for developing a freshness indicator and determining the application of freshness indicator formulations and influencing consumer purchasing decisions.

中文翻译：

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用于监测包装泡菜在储存过程中质量变化的新鲜度指标

摘要 制备了一种pH敏感的染料鲜度指示剂体系，监测泡菜贮藏过程中挥发酸和CO2产生的可见颜色变化。在发酵过程中，泡菜的 pH 值最初为 5.4，降低到 4.2-4.4 的中等值，并在发酵结束时达到 4.0。根据 pH 值和酸度，确定了三个发酵阶段。观察到 pH 值和酸度之间的良好相关性。在最佳发酵阶段观察到最高的 CO2 浓度 (60%) 和有机酸含量 (80 mg%)。新鲜度指示器的颜色变化准确地跟踪了包装顶部空间中 CO2 浓度的增加。所测指标均随着泡菜发酵阶段的不同，呈现出可见的颜色变化，这些值与 CO2 浓度、pH 值和酸度显着相关。在阶段之间观察到的较高 TCD 值与可见颜色变化具有显着相关性。储存、调查和迁移测试结果表明，染料没有迁移到食品材料中，可以安全地在食品包装内使用。这项研究的结果将有助于开发新鲜度指标和确定新鲜度指标配方的应用并影响消费者的购买决策。