Optimization of annatto dye extraction in semi-industrial scale and evaluation of its stability in laboratory scale and food model system

In this research, the effects of solvent type, solvent to seed ratio, temperature and time of extraction on the yield, the color purity and the yield of bixin/ norbixin of annatto were studied. Central Composite Design with 4 parameters including of solvent type (acetone, NaOH and acetone-NaOH), solvent to seed ratio (1:1 to 5:1 ml/g), time (2-6 h) and temperature of extraction (25-65 ºC) in three levels (-1, 0 and +1) was employed. The results indicated that the quadratic model was significant for the yield of annatto and R2 = 0.915, indicating that 91.5 % of the change in the responses could be predicted by the fitted model. In addition, the temperature and time of extraction had no any significant effect on the extraction yield. The maximum yield was predicted by NaOH under the 46.41 ºC, 2.05 h and solvent to seed ratio of 5:1, which was 13.31 %. The quadratic model was significant for the color purity of annatto and R2 = 0.848. By changing the solvent from acetone to NaOH and increasing the solvent to seed ratio, the color purity increased. Furthermore, bixin/ norbixin yield, which is the weight ratio of bixin or norbixin to annatto seed, was determined and calculates as a comprehensive response. The most effective factor in the color change of annatto powder was determined as light and if it removed, using suitable packaging, it would be possible to maintain the best quality of the powder .Similar results were obtained regarding the stability of annatto dye in the whey powder.