Effects of air temperature on the physicochemical properties and flavor compounds of roasted red ginseng lateral roots in a jet impingement fluidized bed roaster

This study aimed to improve the availability of red ginseng lateral roots by applying air jet impingement fluidized bed roasting as a novel processing technology. The effects of air temperature (150 °C, 160 °C, 170 °C, 180 °C, 190 °C, and 200 °C) on the physicochemical properties and flavor compounds of red ginseng lateral roots were investigated. The air roasting time and velocity of the jet impingement fluidized bed roaster were 10 min and 21.68 m s−1, respectively. The moisture content and bulk density significantly decreased, while the total weight loss, expansion index and specific volume significantly increased as the temperature increased (p < 0.05). The extraction yields significantly increased by 38.34% at 200 °C compared with unroasted samples (p < 0.05). The high-temperature roasted sample had larger and more porous structures on their surfaces than the unroasted sample in the scanning electron microscope images. The major ginsenosides (Re, Rg1, Rb1, Rc, Rb2, and Rd) peaked at 150 °C or 160 °C, whereas the minor ginsenosides (Rh1 and Rg2) peaked at 190 °C or 200 °C. Furfural and maltol increased > 444 and > 10 times in the roasted samples at 200 °C and 170 °C, respectively, when compared with the unroasted samples.