c © 2007 Institute of Chemistry, Slovak Academy of Sciences DOI: 10.2478/s11696-007-0034-3 Effect of Gamma Irradiation on Trichromatic Values of Spices*

The effect of γ-irradiation on trichromatic color values L*, a*, and b * was determined in black pep-per, oregano, and allspice samples irradiated at average doses from 5 kGy to 30 kGy. Trichromatic values a * measured in methanol extracts of treated spices immediately after the irradiation process were significantly changed, but the subsequent storage of allspice and oregano caused much more distinctive alteration of these color values than the irradiation itself. Additionally, the differences in redness between the reference (non-irradiated) allspice and oregano samples and samples treated by γ-radiation gradually disappeared during the storage period. On the contrary, the post-irradiation storage of black pepper samples did not reveal any changes of a * values