Purification of anthocyanins from purple sweet potato by combination of ultrafiltration and macroporous resin

The anthocyanins extract from purple sweet potato was purified using ultrafiltration and macroporous resin. The effect of different molecular weight cutoff( MWCO) ultrafiltration membranes to remove the macromolecular substances was investigated. The results showed that the 10 ku membrane could effectively remove the macromolecular substances in the extract. The protein entrapment rate was 93.67%,and the anthocyanins through rate was 86.54%.The soluble solids content was reduced by 14.29%,and light transmittance increased by 23.78%.The adsorption and desorption ability for anthocyanins of six kind of macroporous resins were evaluated.It turned out that LS- 305 was the most suitable resin for anthocyanins. The dynamic adsorption and desorption conditions as follows: flow rate of 5.2 bed volume( BV) / h,the sample volume of 35 BV,60% ethanol used to elute the anthocyanins,and volume of 9 BV could elute anthocyanins completely.As a result,the color value of the anthocyanins from purple sweet potato increased from 1.59 to 32.89 after purification.HPLC analysis showed that ultrafiltration and macroporous resin did not affect the anthocyanins component.