ESR technique was used to detect free radicals present naturally or formed after employing various food processing methods (irradiation, microwave roasting, pan frying and pounding) by entrapping small quantities of seed portions (seed coat and cotyledon) of Canavalia cathartica in potassium chloride powder in ESR quartz tubes. ESR signal at g=2.002 was more prominent in seed coat than the cotyledon. Application of ionising radiation (gamma and electron beam, 10 kGy) resulted in enhancement of signal at g=2.002 accompanied by a weak triplet (a H =3mT) in seed coat, which can be used as a suitable method of detection of irradiation. Some of the commonly employed food processing methods also generated free radicals (at g=2.002) more or less comparable to irradiation. Results of the present study might prove to be beneficial for the consumers who are interested to be acquainted with the status of free radicals in legumes after conventional or modern food processing and preservation methods.