Purification, Identification And Properties Of Purple Cabbage Anthocyanins

Purple cabbage is a variant of cabbage species from brassica, cruciferae,it isan important source of natural pigment because of higher anthocyanins contents,and larger cultivation and planting in China. In this work, enzymatic clarificationon purple cabbage juice extracted,stability and antioxidation of purple cabbageanthocyains were researched. Also, anthocyanins of purple cabbage wereseparated in order to develop purple cabbage anthocyains for using in foodprocessing.First of all, it was conducted to evaluate the effect of pretreatment andenzymatic clarification on purple cabbage juice extracted by the aqueous methodand clarified by pectinase;And response surface methodology (RSM) was usedto obtain optimal clarification technology.It was shown that the pretreatment ofcrush as well as enzymatic hydrolysis conditions such as enzyme concentration,operating temperature and pH had important influences on the clarity of purplecabbage juice; The optimal operating conditions by RSM were as follows:enzyme concentration0.0013mL/100g, operating temperature55.6℃, pH4.1and50min.The highest clarity of purple cabbage juice observed was of99.2%，and the colour value of purple cabbage pigment increased33.6%under theoptimum conditions.Secondly, in order to separation and identification of anthocyanins frompurple cabbage, it was conducted to research the conditions by sephadex LH-20such as elute、flow rate and sample concentration. In addition, different fractionswere tentatively identified by UV-Vis spectrum,thin layer chromatography andHPLC in this work. It was shown that optimum purification conditions were:elution with30%ethanol, with a flow rate of1mL/min, and100mg sample.Under the above conditions, four fractions were collected according to the profile of UV-Vis spectrum. fractionⅠwas not belonged to anthocyains, fractionⅡ,Ⅲ,Ⅳwere belonged to anthocyanins by UV-Vis spectrum. Additionally,fractionⅡ,Ⅲ were separated2anthocyains, and fraction Ⅳ were separated3anthocyains respectively according to the profile of thin layer chromatography.Under the gradient elution, purple cabbage anthocyanins were separated8anthocyains,and peak7(40.51%), peak8(19.61%),peak5(14.12%) is the mainlycontents of anthocyanins form purple cabbage.fractionⅡ、Ⅳwere separated7anthocyains, and fraction Ⅲ were separated5anthocyains respectively byHPLC.Thirdly, it was conducted to evaluate the effects of pH, temperature,ascorbic acid, different metalions and carbohydrates on the stability of purplecabbage anthocyains. It was shown that pH had a great impact on the stability ofanthocyanins pigment. The contents of anthocyanins reduced with the increase ofpH, which decreased rapidly when pH﹥7. Purple cabbage anthocyains pigmentwere more stable to common heat treatment, but less stable when temperaturewas above80℃.The anthocyanins were sensitive to high concentration ofascorbic acid.Na+, K+,Mg2+hardly affected the stability of anthocyains, whileCa2+significantly influenced it, and Zn2+、Al3+had extremely significant effect.Sucrose had significant color-enhancing effects while glucose, lactose andfructose had little effects on the stability of purple cabbage anthocyains.Citricacid and tartaric acid had significant color-enhancing effects.Sodium benzoateand potassium sorbate had little effects on the stability of purple cabbageanthocyains.Finally, the antioxidation of purple cabbage anthocyains was determinedusing six antioxidation reaction systems. The rusults showed that purple cabbageanthocyains had good antioxidant activity. Reducing power of purple cabbageanthocyains increased with the increasing of concentration, and there wassignificant positive correlation between them. The scavenging effect of purplecabbage anthocyanins on0-2·,·OH, DPPH·, ABTS·+increased with theincreasing of concentration, and there was significant dose-effect relationshipbetween them. Reducing power by prussian blue method and the antioxidantcapacities in FRAP system showed significant correlation both.