Heat and Oxidation Stability of Bio-Pigments for Food Coloring

Natural pigments are becoming more important recently due to negative effects posed by synthetic colorants. However, bio-pigments are sensitive to various conditions such as temperature, pH level, storage conditions, and ultraviolet radiation. This project aims to study the heat and oxidation stability of pigments from pandan leaves (Pandanus amaryllifolius) and turmeric (Curcuma longa) by using natural stabilizers which are lye water and ascorbic acid respectively. Chlorophyll pigments from pandan leaves were extracted by blending and filtration. Lye water of different concentrations were added to these pigments. Commercial turmeric powder was mixed with different amount of ascorbic acid. In order to determine their stabilities, themogravimetric analysis was done using heating rates of 10°C/min, 20°C/min, and 30°C/min. Activation energies were then calculated. Fourier transform infrared spectroscopy was used to determine functional groups of the solutions. In both pandan solutions, it was observed that carbon dioxide is present, indicating degradation. In treated turmeric mixture, it was observed that the carbon-hydrogen stretch was less intense. Besides that, lye water was found to reduce chlorophyll degradation at 80°C and ascorbic acid was proven to be an effective oxidation stabilizer.