Esterification Modified Of Anthocyanins From Black Rice And Their Stability Properries

Acylated anthocyanins synthesis with anthocyanins extract from black rice and Succinic anhydride was performed in pure ethanol. Study of Physico-chemical and stabilization properties of the esterification product.Through experiment, The water bath temperature, pH, time and liquid-solid ratio were selected as evaluation factors based on esterification rate. The factors and levels of testing were selected based on single-factor test. Process conditions were determined by three factors three levels of response surface analysis method and based on regression analysis, according to Central Composite (Box-Benhnken) experimental design principles. the significance of each factor and interaction were analyzed according to response surface and contour. The optimum process parameters of esterification are the water bath temperature63℃, time4.0h, liquid-solid ratio7.8:1. Under these conditions, esterification rate is47.8%. The measured rate of esterification is47%to48%after numerous tests in this conditions.The visible maximum absorption of esterification product increase from526nm (black rice)to532.5nm. Infrared spectra obtained:IR spectra of the reaction curve at1724cm-1(ester carbonyl C=O stretching vibration absorption),and1553cm-1(RCOO-characteristic absorption) near the emergence of new absorption peak, esterification after treatment Anthocyanins did not undermine the basic structure of the original pigment, esterification reaction was only in the original anthocyanin molecule has added a new ester group. The high-performance liquid chromatography, liquid chromatography of esterification product appear a new absorption peak at3.9minute, since the whole reaction process does not add other substances, so it can determine the succinic anhydride has received anthocyanin molecules.Overall, the esterification product of the stability of the pH (5～9), temperature (>80℃) and light stability are better than the black rice pigment; the hygiene standards of food additive within the amount of sodium benzoate and potassium sorbate added to the black rice pigment stability and esterification product with no significant impact; Salt and sodium metabisulfte less impact on the pigment;surose on the esterification product of the little effect on absorbance; H2O2will lead black rice pigment and esterification to rapid degradation; Fe3+and Fe2+reduced pigment absorbance values, Al3+, and Zn2+can improve the absorbency of liquid pigment, with hyperchromic effect, and other metal ions on the pigment less affected.