The feasibility of using apparent viscosity (eta a) as a method for detecting the occurrence of previous irradiation of pepper was studied. Apparent viscosity of heat-treated suspensions of white and black pepper, nonirradiated or irradiated with different doses of ionising radiation (gamma), was measured under different "shear rates". Results of previous research were therefore expanded and their usefulness examined; low shear rate conditions were found to be preferable for the detection and semi-quantitative evaluation of irradiation doses. The experimental methodology for semi-quantitative estimation was developed and its scope and limitations are presented.