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With the deepening of medical toxicology and biological research, natural food coloring safe and has a certain physiological functions continue to be favored by the people. Natural pigment extracted from the swimming crab shell, not only for the consumption of natural pigments to add new varieties, also has positive significance comprehensive development and utilization of swimming crab shell. Swimming crab shell pigment extraction, purification and stability. Optimized reflux extraction and microwave assisted extraction of the crab shell pigment crude process conditions; determine the conditions of crab shell pigment saponification of the crude product using silica gel column chromatography separation and purification of the crude pigment; factors such as light, temperature of the crab shell pigment stability. The experimental results are as follows: (1) by a single factor and orthogonal experiment to determine the best extraction process of reflux extraction and microwave-assisted extraction swimming crab shell pigment. Reflux extraction process: material particle size 80 mesh, 60% ethanol, liquid to solid ratio 10:1 (ml / g), extraction temperature 70 ℃, extraction time 105min, extraction times. Where the pigment was 10.28%, the color value of 13.1. Microwave assisted extraction process: material particle size 80 mesh, 50% ethanol concentration, liquid to solid ratio of 15:1 (ml / g), microwave power 300W, extraction time 140S, extraction times. This condition, the yield was 15.97%, the color value of 7.9. Compared with the reflux extraction, microwave assisted extraction time is very short, high pigment extraction but slightly lower PIGMENT price. (2) swimming crab shell pigment crude product saponification conditions: the saponification temperature of 30 ° C, saponification time of 40 min, the the crude pigment oil concentration 10mg/ml, alkali concentration 1.5mol / L. Column chromatography on silica gel using a gradient elution, eluant selected as acetone: cyclohexane: petroleum ether mixed solvent, the ratio (V / V) followed 3:20:4 (54ml) and 3:15:4 (66ml ), 3:12:5 (60ml), 3:10:6 (57ml). The collected solution was concentrated in vacuo to obtain the crab shell pigment red, the yield was 3.71%, the color value 48. (3) swimming crab shell pigment in lower than 75 ℃, dark or natural light, and is relatively stable under acidic conditions; redox agents, pigment degradation and UV irradiation; alkaline conditions, sucrose and K , Na hyperchromic effect on the pigment, Fe 3 , Cu 2 discoloration Ca 2 , Mg < sup> 2 , Al 3 , Zn 2 and citric acid, potassium sorbate, the pigment is almost no effect; high concentration Vc pigment to produce precipitation.
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