Radiofrequency-Assisted Thermal Processing of Soft Wheat Flour

Wheat flour may be thermally processed to improve microbiological safety; however, come-up time for thermal processing of wheat flour is long due to its low thermal conductivity. In the present study, a novel radiofrequency (RF)-assisted thermal processing approach was investigated for reducing the come-up time of soft wheat flour (SWF) and for improving microbiological safety. The temperature and time combinations of 80 °C for 7 and 10 hr, 90 °C for 2 and 3 hr, and 100 °C for 0.75 and 1 hr for RF-assisted thermal processing were selected to achieve a minimum of a 7-log reduction in Salmonella spp. The quality and functional properties of RF-assisted thermally processed SWF was evaluated by solvent retention capacity (SRC), swelling power, sodium dodecyl sulfate sedimentation tests, and rapid-visco-analyzer test, and the values were compared with the untreated (unpasteurized) and commercially pasteurized SWF. All the SRC attributes at 80 °C for 7 hr, 90 °C for 2 hr and 100 °C for 0.75 hr were not significantly different from that of the unpasteurized SWF. The optimum RF-assisted thermal processing conditions of 80 °C for 7 hr and 90 °C for 2 hr were recommended for pasteurization of SWF without any compromise in the quality and functionality. PRACTICAL APPLICATION: Thermal processing of low-moisture foods such as flours and powders through traditional methods is not practical due to extremely long come-up times. Novel radiofrequency-assisted thermal processing is poised to reduce the processing time 89 times for 100 °C. The processing parameters determined in this study will enhance the microbiological safety of wheat flour without compromising the quality and functionality.