The underspecification product obtained from crab stick production is considered as a crab stick by‐product. To extend its shelf life, frozen storage is required but this process is costly due to electricity consumption. Hence, the process for producing a shelf‐stable crab stick by‐product was focused in this study to reduce the cost of storage. For this experiment, the by‐product (73% wet basis) was dried using different drying methods such as freeze drying and convective hot air drying at 50, 60, and 70°C. The qualities of dried products including physicochemical, morphological, and rehydration properties, and adsorption characteristics were assessed. The results found that freeze drying was the best drying method to preserve the qualities of dried sample. Moreover, convective hot air drying at 70 and 60°C gave better qualities (higher porosity, % reconstruction, rehydration properties, and less hardness) compared to 50°C. Adsorption isotherm types II and III were observed in this study. Novelty impact statement In a private company, approximately 10–15 metric tons per day of crab stick by‐product is obtained, meaning that high cost for frozen storage is required. Freeze drying is considered as the best drying method but high production cost, time‐consuming, and more complex in terms of operation are the limitations of this technique. In this work, the influence of drying conditions on physicochemical, morphological, and rehydration properties, and adsorption characteristics of dried crab stick by‐product were evaluated and drying at 60 and 70°C were the effective conditions due to the superior product qualities compared to drying at 50°C.

BACKGROUND Duckweed is considered as a future food material due to its fast growth, high yield, high nutritional value, and low impact on land use. However, in its fresh form, it has high moisture content (95% wet basis), resulting in a short shelf life. In this study, microwave drying (MWD) was conducted to produce a shelf‐stable duckweed with minimal loss of quality. Drying characteristics and quality aspects of dried duckweed were assessed. Reaction order kinetics, including zero and first order, was applied to describe structural changes during drying process. Hierarchical cluster analysis (HCA) was used to select the appropriate drying conditions. RESULTS Of five drying models, the Midilli–Kucuk model was the one that best described the drying process. 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 two main clusters by HCA and the results showed that MWD at 720 and 900 W provided samples that were closer in terms of quality to a freeze dried sample (the positive control) than samples that had been subjected to MWD at 450 W. CONCLUSION Drying behaviors of duckweed were well‐described by the Midilli–Kucuk model. Microwave drying at 900 W gave the lowest energy consumption and displayed the most efficient use of energy. The first‐order equation could be used effectively to describe the structural changes in the duckweed. Microwave drying at 720 and 900 W was the appropriate drying condition according to the HCA classification. © 2023 Society of Chemical Industry.