Optimization of the Blanching Process
Effect of Different Blanching Treatments on the Inactivation of Catalase and POD. Steam blanching resulted in nonuniformity of the enzyme inactivation, and the inactivation time of catalase and POD during steam blanching were consistently higher than that of hot water, acetic acid or calcium chloride solution blanching. Therefore, steam blanching of carrots was not investigated further and the quality loss parameters (b-carotene, vitamin C loss) during steam blanching were not measured. The inactivation time of catalase and POD in hot water, 0.05 N acetic acid and 0.2% calcium chloride solution at selected temperatures are shown in Figs. 1–3. It was observed that the inactivation time for POD was, in general, higher than catalase irrespective of the type of blanching treatment used. Therefore, POD was considered as an index of blanching for carrots. The inactivation time of POD in water blanching was 7 min at 80–90C, 5 min at 95C and 4 min at 100C, respectively. Kidmose and Martens (1999) reported that POD inactiva- tion occurs in 4 min at 90C during hot water blanching treatment.The blanch- ingexperimentsofcarrotsweresubsequentlydoneaccordingtothetimeofthe inactivation of the POD enzyme in water, acetic acid or calcium chloride.