Extraction of organic pigments from tomato (Solanum lycopersicum L.), turmeric (Curcuma longa L.) and red amaranth (Amaranthus tricolor L.) for safe use in agro-products

The utilization of synthetic dyes in food industries is a great concern for food safety and health issues. So, natural pigments can be an excellent substitute for synthetic dyes and also health-friendly for consumers. In the experiment, natural pigments were extracted from tomato (Solanum lycopersicum L.), turmeric (Curcuma longa L.) and red amaranth (Amaranthus tricolor L.). Then the stability and consumer acceptance of the extracted pigments were examined. The highest amount of pigment was extracted from turmeric (2.14 ± 0.30 %) with ethanol solvent, followed by tomato (0.67 ± 0.06 %) with hexane: acetone (1:1) solvent, and red amaranth (0.78 ± 0.05 %) with acetone solvent. Turmeric pigment showed the highest stability in high temperatures and light exposure. All of the pigments were highly stable in a neutral environment; however, tomato pigment showed the highest stability index (84.33 ± 2.52) at pH 3.0, but turmeric pigment showed the highest stability (91.67 ± 1.53) at pH 5.0. The simple preference test revealed that the use of turmeric pigment in boiled rice had the highest acceptance rate, and in terms of taste and flavor, red amaranth pigments in ice cream. So turmeric pigment can be utilized in high-temperature processing and/or acidic foods, but tomato and red amaranth pigments might be in low-temperature processing foods such as the ice-cream and soft drinks processing industry.