Research on production of some natural food colorings

<p class="03Abstract">Steming from the general trend of the world in the use of products from nature, some basic natural food colorings have been produced, including the red from <em>Momordica cochinchinensis</em> fruits, the yellow from <em>Gardenia jasminoides</em> seeds, and the green from <em>Boehmeria nivea</em> (<em>Ramie</em>) leaves. Unlike industrial techniques with usually using non-edible organic solvents, as well as traditional techniques with using hot or cold water extraction, this study used ethanol as a solvent for extraction. The results showed that the use of ethanol without adding water for extraction have obtained the colorings with the highest efficiency. The other conditions were also investigated and selected such as the use of 50 mL of ethanol for 1.0 g of dry materials, the extraction temperature of 70 ^oC, the extraction time of 60 minutes for the red and yellow colorings, of 90 minutes for the green coloring. All studied colorings were stable at high temperatures, which can be heated to 90 ^oC for 60 minutes without any significant changes. When having been stored in refrigerator at 4 °C, the studied colorings were more stable than having been stored at room temperature with the presence of light. They were also more stable when having been stored in ethanol than having been stored in water. After being stored for 6 days in ethanol, the weight of the red, yellow, and green colorings decreased by 2 %, 0.4 %, and 9.6 %, respectively.</p>