Evaluation of capsaicinoid profile and antioxidant properties in dried Korean red pepper (Capsicum annuum L.) as affected by variable dose rates of electron beam and gamma ray irradiation

The application of food irradiation is based on the parameters including energy (MeV), dose rate (kGy/s or kGy/h), and absorbed dose (kGy). Red pepper powders were treated with different dose rates of 1, and 5 kGy/s electron beam (EB) as well as 1.8 and 9 kGy/h gamma ray (GR) in separate experiments. Constant absorbed dose (3 kGy) was maintained to observe whether different dose rates affect the product quality. Total and individual capsaicinoids increased at low EB and GR dose rates. Vitamin C content decreased at all dose rates, except at low GR dose rate, where no significant difference was observed. Low EB dose rate led to a marked increase (21%) in the total phenolics than high dose rate (13%). In contrast, high GR dose rate increased the total phenolics than low dose rate. Maximum antioxidants (1.36 mg TE/mL) were observed at high EB dose rate, although low dose rate also increased the antioxidant activity. Results indicated that different dose rates delivering the same absorbed dose had significant impact on the product quality and that the efficacy of absorbed dose is dependent on applied dose rates. In other words, a constant absorbed dose applied to the product is influenced by dose rate of the irradiation treatment.