Extraction of food dye from tea waste and evaluation of its stability

Tea waste containing significant amounts of polyphenolic compounds can be used for dye extraction. In this study the different condition of dye extraction from black tea waste were investigated and dye stability was evaluated during storage. In dye extraction process, three factor including ratios of water: ethanol (50:50, 30:70, 10:90 and 0:100), temperature (ambient, 50°C and the boiling point of solvent) and time (30, 60 and 90 minutes) were investigated. The extracted color in optimum conditions was filtered, concentrated and sterilized and then used for stability evaluation. Three factors including temperature (4 and 25°C), light (light and dark) and time of storage (at intervals of 10 days during 60 days) were used for evaluation the stability of color. Changes the total color and color intensity was measured using a spectrophotometer. The results showed the best extraction condition was in water: ethanol 50:50 at the boiling point during 30 minutes. It was significant difference with other treatments (p <0.01). The storage temperature had significant effect on color stability but light had no significant changes. The changes in color stability were maintained at 4 ° C. Color intensity was higher in alkaline media and was no difference in acidic. No microbial growth has seen in the samples stored at room temperature. The color did not make a significant difference in taste of jelly (p <0.05).Key words: tea waste, polyphenols, natural color, stability.