Microwave Drying of Ginger by Online Aroma Monitoring

The organoleptic response elicited by a food product's aroma plays a substantial role in defining the product's quality, greatly influencing consumers' choices and purchasing. In this study optimal microwave drying condition for ginger (Zingiber officinale Rosc.) in terms of minimum aroma loss was established thanks to rapid online monitoring of aroma profiles with a zNoseTM (Newbury Park, CA, USA). Ginger cubes were dried at temperatures of 40, 50, 60, and 70°C. Drying temperatures were carefully controlled with appropriate microwave power levels. Energy consumed for each process was recorded in terms of mean power rate (W/g) and total energy consumed (kJ/g). Volatile peaks observed throughout the drying process were carefully identified and recorded. Dried ginger quality was also evaluated in terms of surface color, coefficient of rehydration, and aroma analysis of rehydrated samples. Lower temperature (40°C) drying avoided product charring but led to substantial losses in the sample's aroma due to the long drying period. By contrast, drying at higher temperatures reduced aroma losses (due to the short drying time) but led to sample charring, making the product unacceptable. Based on the analysis of the aroma profiles and the results of the above-mentioned quality evaluations, it was concluded that the best product quality could be achieved by drying at 60°C.