LAUSR

BACKGROUND Due to its fast growth rate, high production yield, high nutritional values and low impact on land use, duckweed is considered as future food material. However, in the fresh form, it has high moisture content (95% wet basis), resulting in a short shelf-life. To produce a shelf-stable duckweed with minimal loss of quality, microwave drying (MWD) was conducted in this work. Drying characteristics and quality aspects of dried duckweed were assessed. Moreover, reaction order kinetics including zero and first orders were applied to describe structural changes during drying process. Hierarchical cluster analysis (HCA) was used to select the appropriate drying condition. RESULTS Among five drying models, Midilli-Kucuk model was the best-describing model. Drying at high microwave power could reduce energy consumption and increase energy efficiency. Increasing both microwave power and drying time increased the structural shrinkage rate as described by first order reaction kinetics. High correlations among quality parameters were observed using Pearson's correlation. Drying treatments were differentiated into 2 main clusters by HCA and the results showed that MWD at 720 and 900W provided closer quality aspects to freeze dried sample (positive control) compared to that at 450W. CONCLUSION Drying behaviors of duckweed were well-described by the Midilli-Kucuk model. MWD at 900W gave the lowest energy consumption and the highest energy efficiency. The first order equation could be effectively used to describe the structural changes of the duckweed. MWD at 720 and 900W were the appropriate drying conditions according to the classification by HCA. This article is protected by copyright. All rights reserved.