| Purple cabbage has been widely planted in China due to its advantages such as rich nutrition, bright color, cold-tolerance, heat resistance and easy transportation. Purple cabbage pigment belongs to anthocyanins (Acys), which are a group of plant pigments that are widely distributed in nature, among flowers, fruits and vegetable. Acys have strong antioxidant and free radical scavenging capacity. The purple cabbage edible method is mainly raw, usually as western food and vegetable salad, to the greatest degree of preservation of its nutritional components. Taking purple cabbage from markets of Wuxi as raw material, the extraction, antioxidative activities and composition of purple cabbage pigment were studied. The thesis mainly includes the following three parts: 1. The extraction and purification of purple cabbage pigment. 2. Study on the antioxidative activity of purple cabbage pigment. 3. The analysis of components and structures of purple cabbage pigment.In chapeter 2, the extraction of purple cabbage pigment was carried out at room temperature by ultrasonic assisted extraction method. The single factor and orthogonal tests were investigated to determine the optimum conditions. The optimal parameters of extraction were as fellows: ethanol–water (60:40, v/v) as extracting solvent, solid-liquid ratio 1:50, extracting time 60 min. Extracts were purified though AB-8 resin column.In chapter 3, the total flavonoids contents of purple cabbage extracts were 3.4 mg/g. The antioxidative activities were investigated by two different methods in scavenging DPPH·radical and restraining lard oxidation. Two antioxidative experiments showed that the antioxidative activity: BHT>purple cabbage pigment >VC.In chapter 4 and 5, Liquid chromatography-mass spectrometry (LC-MS) and capillary electrophoresis with electrochemical detection (CD-ED) were applied to determine the components and structures of purple cabbage pigments. The result shown that a total of seven Acys were detected in purple cabbage pigments, which were a series of cyanidin glycosides and acylated cyanidin anthocyanins.Capillary electrophoresis with electrochemical detection (CD-ED) method was applied to determine four organic acids which were acylated groups in the purple cabbage anthocyanin. There are sinapic acid, ferulic acid, p-coumaric acid and caffeic acid, respectively. A 300μm diameter carbon disk electrode was used as the working electrode and 60 mmol/L borate solution (pH8.7)was used as running buffer. Each component can be completely separated within 12 min, at the most optimal conditions: detection potential 0.9 V, separation voltage 14 kV, injection time 6 s.Injection standard sample 7 times continuously, the relative standard deviations (RSD) on peak height were: 2.7%, 2.4%, 1.6% and 4.1% for sinapic acid, ferulic acid, coumaric acid and caffeic acid, respectively. Peak heights and concentrations have good linear relationship. Linear range were: 5.0×10-7～1.0×10-4 g/mL, 5.0×10-7～1.0×10-4 g/mL, 1.0×10-7～1.0×10-4 g/mL, 5.0×10-6～1.0×10-4 g/mL. Detection limits (S/N=3) were: 2.5×10-7, 3.0×10-7, 3.2×10-8, 5.0×10-7 g/mL. The method was simple, high sensitive and simple sample treatment. It provides a fast and sensitive detection method for identification of Acys. Compared with other plants, Acys in purple cabbage are more complicated, because of the high number of different Acys and their complex structures. This topic research for purple cabbage pigment further exploitation provides certain theoretical basis.
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