LAUSR

This study aimed to extract and identify anthocyanins from Nitraria tangutorun Bobr. dry fruit and evaluate the stability of anthocyanins in aqueous solution and taurine-contained beverage. Extraction at 68 °C for 30 min using 54% ethanol rendered an extract with 386.22 mg/100 g of anthocyanins. Fourteen anthocyanins in N. tangutorun dry fruit were identified using HPLC-DAD-ESI-MS/MS, and six of them were found in N. tangutorun dry fruit for the first time. The stability of anthocyanins and changes in color density and antioxidant activity of anthocyanin aqueous solution were evaluated at various pH and temperature levels using an accelerated thermal-stability assay. The degradation of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total anthocyanins and the loss of color density followed first-order model at studied conditions (R2 > 0.91); and the loss of antioxidant activity followed first-order model at 80 and 90 °C (R2 > 0.94). The Ea of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total anthocyanins were higher at pH 3 than that at pH 4 and 5 implying that the degradation of them at a lower pH level was more susceptible to temperature. Although the anthocyanins and color density were markedly loss with increasing the pH and temperature levels, the anthocyanin aqueous solution exhibited remarkable antioxidant capacity. In the beverage with or without taurine, the thermal degradation of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total anthocyanins also followed first-order model (R2 > 0.91), and 300 mg/100 mL of taurine provides protection for the stability of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside (t1/2=438.61 min) and total anthocyanins (t1/2=391.53 min). N. tangutorun anthocyanins is promising natural food pigments.