Analysis of volatile compounds of ginger (Zingiber officinale) during far-infrared combined with hot-air drying by GC-MS and MOS e-nose

Abstract

In this study, ginger slices were dehydrated through a combination of far-infrared radiation and hot-air drying (FIR-HAD). The changes in volatile composition were subsequently identified using gas chromatography-mass spectrometry (GC-MS) and metal oxide semiconductor electronic nose (MOS e-nose). The GC-MS analysis revealed that terpenes comprised over 75% of volatile compounds in all examined samples, with zingiberene, β-sesquiphellandrene, and (E, E)-α-farnesene being the dominant constituents. Fresh ginger contained a higher relative proportion compared to dried samples. After FIR-HAD treatment, the terpene levels decreased by 11.9%, 8.9%, 13.7%, and 18.2% at 50 °C, 60 °C, 70 °C, and 80 °C, respectively. Among the various drying conditions, ginger subjected to FIR-HAD at 60 °C displayed the highest concentrations of volatile compounds and exhibited flavor characteristics closest to those of fresh samples. The flavor profiles were further evaluated using MOS e-nose analysis. The terpene compounds demonstrated a strong correlation with the response values of W1W and W2W sensors according to partial least squares regression models. In addition, the concentrations of 6-gingerol, 8-gingerol, and 10-gingerol in ginger exposed to FIR-HAD at 60 °C were also higher compared to other drying conditions. This indicated that the FIR-HAD at 60 °C is more suitable for producing dried ginger with remaining flavor attributes. These findings offer theoretical insights into the changes in volatile compounds of ginger slices during the FIR-HAD procedure. They also highlight the potential for improving drying efficiency through aroma online control techniques in future research.