Developing effective radio frequency and ultraviolet combination technology based on evaluating quality characteristics of buckwheat

Radio frequency (RF) heating and ultraviolet (UV) radiation are widely used in food processing. In this study, effects of RF and UV treatment alone and in combination on quality characteristics of buckwheat were investigated and compared under the operational parameters used for effective food decontamination. Results showed that RF heating at the high temperature (H-RF, 105 °C) led to significant changes on physicochemical properties of buckwheat, including an increase in water absorption capacity (WAC), and decreases in swelling power (SP), emulsifying capability (EC), foaming capacity (FC), viscosity capability, gelatinization enthalpy (ΔH), and rheological property. Correspondingly, intermolecular hydrogen bonds were broken, short-range order degree (ratio of 1047/1022 cm−1 and 995/1022 cm−1), crystallinity degree, and SH group contents were reduced. The changes of these parameters were mitigated by RF treatment at the low temperature (L-RF, 90 °C). While the UV radiation only affected the FC, EC, viscosity capability, and rheological property. Especially, UV radiation at low intensity (L-UV, 2.25 mW/cm2) alone did not significantly influence the multi-scale structures and physicochemical properties of buckwheat. Meanwhile, buckwheat treated by L-RF alone or in combination with L-UV performed the similar properties, implying that the UV treatment after RF heating could not further alter the quality of buckwheat. These results would provide basic information for the selection of suitable treatment to meet the needs of developing an effective treatment process.