Extraction of Food Colorant from Amaranth Celosia Cristata Leaf and Evaluation of Its Stability

Amaranth scientifically named Amaranthus celosia cristata belonged to Amaranthaceae is one of the plants which contains betalain pigments. In this study, after extraction of Amaranthus leaves by two solvents (methanol-water acidified and non-acidified) and two methods (dehydration and solid-liquid extraction), the stability of the selected extract was investigated under various conditions such as pH, temperature, light and darkness. The results of pH effect on extract stability showed that the highest adsorption was related to pH=5 and the lowest to pH=8. With increasing temperature (4 to 60°C), the extract stability decreased significantly. Moreover, increasing the incubation time of the extract at any temperature (except 4°C) caused a significant reduction in the stability of the extract (p <0.05). Storage of the extract in different light conditions (darkness, visible light and ultraviolet) for different periods of time showed that the highest stability was related to the dark conditions and increasing the storage time reduced the stability of the extract in each case. The results showed that the extract was more stable at temperatures below 25 °C, pH=5 and darkness. This natural colorant can be used in food products such as ice cream, ice syrup, yogurt, and in the coloring of easily-swallowed candy, sweets, and mid-cream.