Effects of Clarification and Pasteurization on the Phenolics, Antioxidant Capacity, Color Density and Polymeric Color of Black Carrot (D aucus Carota L.) Juice

Abstract

This study was conducted to investigate the effects of clarification and pasteurization on the total phenolic (TP) contents, hydroxycinnamic acids (HCAs) and antioxidant capacity (AOC) values of black carrot juices (BCJs). The effects of the phenolic compounds on the color density (CD) and polymeric color values were also evaluated. Depectinization (13 and 59%) and pasteurization (1.1- and 2.3-fold) treatments led to increases in the TP and HCA contents in the BCJ, and bentonite (10 and 7%) and gelatin–kieselsol (25 and 29%) treatments led to reductions. Chlorogenic acid (CGA) was identified as the major HCA by high-performance liquid chromatography–mass spectrometry. There were strong correlations between the AOC values with the TP and HCA contents (r = 0.750–0.996). Additionally, there were significant effects from the ratios of anthocyanins (ACN) to HCAs and ACN to CGA on the degree of polymerization. Because of the increased TP and HCA contents with AOC and CD values, depectinization and pasteurization were recommended for BCJ production. Practical Applications There is great interest in black carrot juice (BCJ) because of its high antioxidant capacity and intense color. After pressing, BCJ should be depectinized to produce juice with a high antioxidant capacity. To produce BCJ with an intense color, the depectinized juice should be clarified with bentonite. Gelatin and kieselsol led to a substantial reduction in color. To produce clear BCJ, clarification should include bentonite in addition to gelatin and kieselsol. However, the gelatin and kieselsol dosages should be carefully determined.