Investigation of radio frequency heating as a dry-blanching method for carrot cubes

Radio frequency (RF) heating was investigated as a novel dry-blanching method for carrot cubes in this study. RF heating uniformity and effectiveness for inactivating peroxidase (POD) in carrot cubes were evaluated along with carrot quality (texture, color and vitamin C (Vc) content) after blanching. Results showed that RF heating uniformity increased with increasing RF electrode gap, and was affected by container shape and size, in which carrot cubes filled in cylinder shape container had better RF heating uniformity than that in rectangle container. Besides, POD activity of carrot cubes was reduced by 90-95% after RF blanching for 3.0-7.0 min at different electrode gaps (8.0-8.6 cm). RF dry-blanching maintained hardness, redness and Vc content of carrots cubes much better than hot water blanching. This study indicated that RF heating is an effective dry-blanching method for carrot cubes.