Effect of thermal treatment on radical-scavenging activity of some spices

Changes in the radical-scavenging activities and the total phenol content of sixteen spices (clove, allspice, cinnamon, nutmeg, mustard, cumin, ginger, fennel, fenugreek, black pepper, red pepper, mace, coriander, turmeric, cardamom and white pepper) were determined for different heating times (1, 3 and 6 h) at 100 degrees C. Most of the spices showed high 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity (4-1353 mu mol Trolox eq./g), peroxy radical-scavenging activity (31-1019 mu mol Trolox eq./g), and total phenol content (5-1267 mu mol gallic acid eq./g). Clove was found to have the highest radical-scavenging activity followed by allspice and cinnamon. After heating, both DPPH and peroxy radical-scavenging activities as well as the total phenol content increased in most of the spices. A distinct increase in the activities was found in some spices such as black pepper, red pepper and turmeric. A high correlation coefficient was found between the total phenol content and peroxy radical-scavenging activity.