pH-sensitive colorimetric indicator, also known as chemical barcode, can provide consumers with food freshness information during storage and logistics through visible color change of indicator system. Because of its rapid, compact size, low-cost and non-destructive, it has aroused great interest in food industry. The principle of this system is based on specific chemical interactions between spoilage metabolite and acid-base dye. At the outset, some chemical reagents such as bromophenol blue, bromocresol green and bromocresol purple have been chosen as acid-base dyes. But, the application of synthetic chemical dyes in intelligent food packaging is limited because of possible toxicity and potential risk to human health. Thus, the natural plant-derived dyes attract more and more attention in recent years. In this study, two natural dyes, extracted from Arnebia euchroma (Royle) Johnst root and grape skin respectively, were incorporated into a polysaccharide matrix to constitute food freshness indicator system. These two natural plant-derived dyes respectively represent hydrophilic and hydrophobic substance. They showed different properties because the nature of color change of dye is proton transport process and the speed of this process depends on the relative humidity of the exposure environment. The color sensitivity, stability and security of two plant-derived dyes in food freshness indicator system were researched. The results showed that the hydrophilic dye has higher color response efficiency but poor stability and security compared with hydrophobic dye.

Characteristic evaluation of natural plant-derived dyes in food freshness indicator system: Color sensitivity, stability, and security

2019 Fall National Meeting

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