Study On The Preparation,Stability And Antioxidant Activity Of Brassica Napiformis Red Pigment

Brassica napiformis,a common vegetable of the Brassica genus,belongs to the cruciferous family,which is in urgent need of further processing,utilization and development.It is widely planted in China and is mainly processed into pickled vegetables for consumption.In order to realize the high-value processing of Brassica napiformis,this paper selected Brassica napiformis as raw material to extract and refine the Brassica napiformis red pigment,and studyed the stability and antioxidant activity of the Brassica napiformis red pigment.The main research results of the thesis are as follows:(1)The extraction condition of Brassica napiformis red pigment were determined.The optimal heating temperature for the production of Brassica napiformis red pigment was 80 ?,the heating time was 3 h and the ethanol concentration was 80%.Under this condition,the yield of the crude red pigment of the Brassica napiformis was(1.45±0.12)%.(2)A two-stage refining process for Brassica napiformis red pigment was established.The crude red pigment of Brassica napiformis was adsorbed by AB-8macroporous adsorption resin and desorbed by 5% ethanol,which could effectively remove impurities such as protein and carbohydrate.The yield of the primary refined red pigment is(3.26±0.014)%.Secondary refined red pigment was purified by semipreparative liquid chromatography after elution with 30% methanol containing 1% formic acid.HPLC analysis showed that the secondary refined red pigment was a single chromatographic peak.And the analysis of LC-MS/MS suggested that the Brassica napiformis red pigment may contain peony anthocyanin.(3)The factors affecting the stability of the red pigment of Brassica napiformis were investigated.The maximum absorption wavelength of the red pigment of Brassica napiformis did not change with the change of p H value.When the p H was less than 5.0,both the primary and secondary refined red pigments were relatively stable.When the p H was greater than 5.0,the absorbance of the two red pigments decreased with the increase of p H,and the color gradually changed from red to light yellow.The time dynamic change analysis of p H value on the stability of red pigment showed that the absorbance did not change with time within 2-8 h under the same p H value.Compared with the low temperature and dark environment,the stability of the two refined red pigment was significantly reduced by high temperature illumination.The red pigment remained stable in the high temperature illumination environment when existed in solid form.Different food additives had different effects on the stability of the red pigment.Sugar additives and antioxidants had little effect on the stability of red pigment,metal ions could significantly improve its absorbance,and food preservative sodium metabisulfite could significantly reduce the absorbance of red pigment.(4)It was proved that the red pigment of Brassica napiformis has antioxidant activity.The red pigment had significant scavenging ability on DPPH,ABTS and hydroxyl free radicals.Further Ha Ca T cell experiment showed that the red pigment could play an antioxidant role in protecting cells damaged by UVB by increasing SOD activity and GSH content,reducing MDA content.