Pectic Enzymes Related with the Formation of Coagulum in Carrot Juice

Abstract

This study was conducted to investigate the relationship between several blanching conditions and remaining enzyme activities, especially pectinesterase (PE) and polygalacturonase (PG), on the formation of coagulum. Eight commercial enzyme preparations were added to carrot juice, and PE or PG caused coagulum formation while the other six enzymes had no effect. Since the endogenous activities of PE and PG were also observed in carrots, these activities were believed to be a major cause of coagulum formation. Coagulum formation was prevented under blanching conditions above 70°C, at this temperature, PE activity was inactivated, and PG activity was reduced about 60% in relation to the non-blanching juice. Since blanching in a 0.02 M citric acid solution (pH 2.4) at 60°C prevented the formation of coagulum, blanching under low pH conditions was more effective. Although PE activity was not reduced in relation to blanching in water at 60°C, the reduction of PG activity was 14%. These results lead to the conclusion that coagulum formation in carrot juice depended on the remaining activities of both PE and PG and that to prevent coagulum these enzyme activities must be suppressed.