Introducing and Efficiency of Some Natural pH-Indicators for Use in Smart Food Packaging

The usage of pH indicators that discolor with spoilage and pH changes of the food has been considered in the food packaging, recently. Some herbal products and their residues that contain pH sensitive compounds can be introduced and used to produce smart, healthy and cost-effective packaging in food products. In this study, the efficiency of borage flower, red apple peel, red cabbage, red radish peel, barberry fruit, red beet root peel, mallow flower and eggplant peel extracts was investigated against pH changes. After preparing their aqueous-ethanolic extracts by maceration method, their color response were evaluated at pH range of 3-12 using hydrochloric acid and sodium hydroxide solutions. The color changes of the extracts were analyzed by UV-visible spectroscopy in wavelength range of 300-800 nm. According to the findings, red cabbage and red radish peel extracts showed a wider range of color changes at different pH than the other extracts, and red beet root peel, mallow flower, borage flower, eggplant peel, apple peel and Barberry fruits were placed in the next ranks, respectively. It can be concluded that red cabbage and red radish peel extracts are more sensitive to pH changes and show the color responses with the higher accuracy than the other extracts and can be introduced as natural cost-effective pH indicators in smart food packaging for timely monitoring of food spoilage.