Antiradical, pH and ammonia sensitive properties of Aronia melanocarpa L. and Beta vulgaris L. aqueous extracts

Plant extracts have received much attention according to the wide area of potential applications. In recent years, pH-sensitive colorimetric indicators as the part of intelligent packaging are developed on plant extracts basis. In this study, aqueous extracts of black chokeberry and red beetroot as pH-sensitive indicators were obtained. Extraction was carried out with a material-to-liquor ratio of 1:10. The total anthocyanins content of the black chokeberry extract was 175.43 ± 21.83 mg of cyanidin-3-glucoside equivalents/L. The beetroot extract showed the betacyanins content of 457.95 ± 0.66 mg betanin equivalents/L and the betaxanthins content of 238.12 ± 1.02 mg vulgaxanthin I equivalents/L. The effect of pH on color behavior of extracts was examined in the pH range of 2–12. The black chokeberry and beetroot extracts presented an obvious color change while the pH changed from neutral to slightly alkaline. The antiradical activity assay of extracts was carried out using the DPPH radical method. The black chokeberry extract was found to have the highest antiradical activity among the investigated extracts with the concentration needed to scavenge the 50% of radical (EC50) of 5.89 µL/mL. The extracts exhibited a distinguishable color response to ammonia exposure confirmed by ΔE values. The plant extracts have potential as colorimetric indicators in pH-sensitive intelligent packaging for meat products.