Impacts of ohmic heating on decorticated and whole pearl millet grains compared to open-pan cooking

Abstract

The effects of two cooking methods, ohmic heating (OH) and conventional open-pan (CONV) on the cooking yield, texture profile analysis (TPA), color parameters, water absorption (WAI), solubility index (WSI) and pasting properties (RVA) of pearl millet grains (Pennisetum glaucum (L.) R. Br.) were investigated. Whole grains were pre-processed by mechanical decortication for 5 min to obtain a 9.1% degree of decortication. The optimum cooking times (OCT) of the whole and decorticated grains were 30 min and 20 min, respectively. The grains were cooked by the OH and CONV methods using a millet-water ratio of 1:2. The OH cooking yield was lower than CONV. The OH cooking did not soften the grains faster than CONV cooking. OH affected the TPA and color of decorticated grains significantly, resulting in greater L* than the CONV-Decorticated. OH did not affect WAI and WSI in comparison to CONV method. The paste viscosity profiles of whole and decorticated grains cooked by both heating methods were similar indicating a comparable effect of starch conversion. This research shows that the main factor affecting the cooking process was the pericarp of the grain rather than the heating method.