Study On Extraction, Purification And Stability Of Pigment From Portunid Carapace

With the development of medical toxicology and biology, people prefer the natural edible pigment of the safe and physiology function. The pigment extracts from Portunid carapace is a natural pigment, which can increase the kinds of natural pigment, but also has positive significance for comprehensive exploitation and utilization of portunid carapace.The paper studied the extraction and purification technics,the stability of the pigment from Portunid carapace.The condition of conventional solvents extraction, microwave-assisted extraction for extracting crude pigment was optimized;the saponification condition of crude pigment was confirmed; the crude extracts was separated and purified by silica gel; the common effects, such as light,temperature and so on, on the stability of the Portunid pigment was studied. The results were as following:(1)The optimum extracting conditions for solvent extraction and microwave-assisted extraction of pigment in Portunid carapace were studied by single factor analysis and orthogonal test. The optimal conditions of conventional solvents extraction were as follow: material sizes, 80 mesh; ethanol concentration, 60%; ratio of liquid to material,10: 1 (ml/g); extraction temperature, 70℃;extraction time, 105min; extraction time, 1 time. At this condition, the yield of pigment was 10.28%, color scale was 13.1. The optimal conditions of microwave-assisted extraction were as follow: material sizes,80 mesh; ethanol concentration,50% ; ratio of liquid to material,15: 1 (ml/g) ; microwave output power,300W;extraction time, 140s; extraction time, 1 time. At this condition, the yield of pigment was 15.97%, color scale was 7.9. Compared with conventional solvent extraction, the microwave-assisted was rapid and qualitatively extraction, but the color scale was lower.(2)The optimal saponification conditions of crude pigment were performed as: saponification temperature 30℃; saponification time,40 min; the concentration of crude pigment oil, 10mg/ml; the concentration of KOH,1.5mol L. The crude extracts after saponification was separated and purified by silica gel, eluted fractionally by acetone / hexahydrobenzene / petroleum leve, the proportion (V/V)was: 3:20:4 (54ml),3:15:4 (66ml),3:12:5 (60ml), 3:10:6 (57ml) .The red collection separated by silica gel was condensed at vacuum condition and the yield of pigment was 3.71%, color scale was 48.(3)The pigment resistant to heat under 75℃, dark, sunlight and acid; in oxidant-reductant, and under U-V light, the pigment can decompose; in condition of alkali, cane sugar and metal ion , such as K+,Na+ can add its color; Fe3+,Cu2+ can change its color; Ca2+,Mg2+,Al3+,Zn2+and common food additives, such as citric acid, potassium sorbate can not badly affect it at all; high concentration of Vc can make the pigment to produce precipitation.