Physico-chemical properties and stability of pigment from purple sweet potato
The solubility in different solvents and the absorbance spectrum of purple sweet potato pigment(PSPP) from Ipomoea batatas Lam were observed,and the effects of pH value,temperature,lighting,H2O2,Vc and Fe3+,Al3+,Zn2+,Cu2+ on PSPP stability were investigated.The result showed that PSPP is water soluble pigment.At the range of pH value from 1.0 to 3.0,PSPP water solution has a bright color and PSPP keeps sta-ble very well.With the increase of pH value,its degradation index increases.When temperature is over 60℃,the stability of PSPP decreases quickly.After accepting 8 day's successive lighting,the retention rate of PSPP was 87%.The pigment has a low stability to H2O2 and Vc.And the A13+,Zn2+ could improve the stability of PSPP,but Fe3+ could damage it.