| Cochineal dye can be used in food, medicine and cosmetics in the United States Food and Drug Administration. There are little research on the pigment in my country. Experiment parameters of the extraction of cochineal dye were optimized. For purification method, the method of ultrafiltration membrane and silica gel column chromatograph were used, and determine the main ingredient. The factors affecting pigment stability are discussed.The main results were as follows:1 The experiments on the extraction process optimization showed:①The optimum extracting condition of solvent method was temperature 80℃for 5 hours, ratio of material to liquid is 1:4 with pure water,6 times, extracting rate 94.95%. The order of extract factor is temperature>time>the ratio of material to liquid.②The optimum extracting condition of ultrasonic assistant method was frequency 20KHz, power 1400W for 12 minutes, ratio of material to liquid is 1:6 with pulse time (10s,4s),5 times, extracting rate 95.05%. The order of extract factor is time>pulse time on>pulse time off>power>the ratio of material to liquid.③The optimum extracting condition of ultrasonic assistant method was frequency 2450MHz, power560W for 40 seconds, ratio of material to liquid is 1:4 with pure water,10 times, extracting rate 95.16%. The order of extract factor is power>time>the ratio of material to liquid.④Cochineal dye of the three extracting method was obtained with yield over 42%(±0.1%) and purity over 32%(±0.1%).2 The refinement condition of cochineal dye by ultrafiltration membrane was as following:feed at room temperature; pressure to 68.95kPa and filtrating the supernatant by the spiral-PES membrance with molecular weight cut-off of lOkD. By this process 54.77% cochineal protein can be removed out of the cochineal extract, and the content of carminic acid reached 53.46% with the pigment loss rate at 15.6%.3 The optimal conditions for the Silica Gel Column Chromatography were obtained as follows:the eluting agent was chloroform, methanol and water, using gradient elution, the initial water content in silica gel was in the range of 10%～14%, flow rate 5mL/min, sample load 0.9g/100g。After the process of silica gel column chromatography, the recovery of cochineal dye may be more than 75.61%and the content of carminic acid can reach 54.37%.4 Cochineal dye was carried out a gel further process after the silica gel purification, the purity over 85.76% and yield over 69.53%. The methanol eluting agent was washed at a flow rate of 50ml/h.5 Solubility experiment show that cochineal dye was water-soluble pigment. The color reaction, UV-Vis spectroscopy, IR spectroscopy and MS spectrum can verify the structure of cochineal dye belong to hydroxyl anthraquinone. The quality of the pigment was in line with relevant standards. 6 The experiments on the purification of the pigment showed:①Cochineal dye was stable at pH=1～9. But the pigment was precipitated easily under pH>10.②Cochineal dye was stable to natural light and dark in the room, and outdoor natural light will gradually degraded the pigment.③Cochineal dye was stable to heat, oxidants and reductannts.④Cochineal dye was sensitive to Fe2+, Fe3+ and Cu2+, and stable to K+, Na+, Ca2+, Mg2+andZn2+.⑤The color of cochineal dye was changed when using sodium benzoate and potassium sorbate as preservative. By comparison, potassium sorbate is not conductive to the stability of the pigment.⑥There are no significant impaction on the cochineal dye with the addition of citric acid, Vc, malic acid, tartaric acid, especially the malic acid can enhance its stability.⑦There are no significant influence on the cochineal dye with the addition of sugars such as glucose, sugar, and lactose. |
PDF Full Text Request