Characterization of tannin based colorimetric indicator and its application on fish packaging

Abstract

This study aims to determine characteristics of the gel-type colorimetric indicator at various pH and under different storage conditions, then determine the indicator characteristic in the packaging of fish fillets during storage. The gel-type color indicator was synthesized with a concentration of 1%, 3%, and 5% gambir powder. The FT-IR spectra of the color indicator showed the presence of tannin functional groups, namely C=C aromatic rings, C-C phenolic, and C-H groups, respectively at wavenumbers 1517-1519, 1440-1475, and 752-761 1/cm. Moreover, the coefficient value of the Red-Green-Blue (RGB) of the indicator was changed over pH and did not appear to be consistent. Based on the Analysis of Variance (ANOVA) test, the concentration of gambir powder and duration of color indicator storage, respectively, had a significant effect (P <0.05) on the value of the RGB coefficient. The color indicator exposed to sunlight had a smaller RGB coefficient value than the RGB coefficient value of the indicator stored at room temperature and 5-7°C. The application of color indicators with a 1% Gambir powder concentration in fish fillet storage has been tested for 5 days at a temperature of 5-7°C. They showed that the RGB coefficient value of the indicator was proportional to changes in the pH value of fish fillets but not in line with changes in Total Volatile Based Nitrogen (TVBN) of fish fillets.