Convective and pulsed microwave drying of lemongrass (Cymbopogon citratus) shreds: Kinetic modeling, retention of bio‐actives, and oil yield.

An experimental study was conducted to assess the drying kinetics of lemongrass shreds, dried using two different drying methods and retention of bioactive compounds in the dried lemongrass. Convective drying (CD) was carried out at 45°C for 7 h, whereas during pulsed microwave drying (PMD), lemongrass shreds were exposed to microwaves at 1350 W for 3‐3‐2‐1‐min pulsed intervals with a 30‐s pulse gap. Experimental data were fitted to three drying models, namely Lewis, Henderson and Pabis, and Page models, to determine the moisture ratio as a function of drying time. The bioactive compounds were analyzed before and after drying to assess the changes during the drying process. Pulsed microwave dried samples showed maximum retention of total chlorophyll: 13.85 mg/g, ascorbic acid: 17.80 mg/100 g, flavonoids: 2.64 mg/g, and highest antioxidant capacity of 74.02%. Moreover, microwave‐assisted hydrodistillation (MAHD) of these samples yielded 1.54% essential oil with a specific gravity of 0.89. Novelty impact statement: The synergistic influence of PMD and MAHD process on the quality of dried lemongrass shreds has not been investigated earlier.Polynomial fit‐MR and polynomial fit‐lnMR for moisture ratio were found to have the highest R2 values for both drying methods.Retention of bioactive compounds was observed to be higher in PM dried samples compared with convective dried samples. [ABSTRACT FROM AUTHOR]