Extraction of Chitin from Shrimp Shells using Microwave: Optimization of Protein Removal based on Central Composite Face-centered Design

The objective of this study is to extract chitin from shrimp shells by removing minerals and proteins using a microwave heating method. The optimal conditions for protein removal were proposed using response surface analysis. Experiments on mineral removal were conducted under discontinuous conditions with irradiation time (1~5 min), temperature (90~130℃), and irradiation power (400~1,600 W). Following the mineral removal process, protein removal experiments were performed under discontinuous conditions with irradiation time (1~10 min), temperature (40~100℃), and irradiation power (400~1,600 W). To identify the optimal points and interactions between factors for protein removal on a continuous scale, the central composite face-centered design, a type of response surface analysis, was employed. Independent variables were set as temperature (40~100℃) and irradiation power (600~1,600 W). Under discontinuous conditions, mineral removal experiments resulted in over 99.9% mineral removal efficiency at 3 min, 100℃, and 1,600 W. For protein removal, maximum efficiency of 94.9% was observed at 3 min, 40℃, and 1,600 W. Lower temperatures resulted in higher protein removal efficiency. Higher irradiation power led to increased protein removal efficiency. The optimal conditions for protein removal in continuous scale experiments were found to be 40℃ and 1,600 W. Under these conditions, a removal efficiency of 95% was achieved. All independent variables significantly influenced the removal process using microwave heating, with p<0.05. The chitin extracted in this experiment exhibited an α-chitin structure with a crystallinity of 84.5%, which is higher than that of commercial chitin (82.1%). Observation of the chitin surface confirmed increased porosity and the removal of minerals and proteins. Mineral removal achieved over 99.9% removal efficiency at 3 min, 100℃, and 1,600 W. The optimal conditions for protein removal in chitin extraction from shrimp shells are 40℃ and 1,600 W. The extracted chitin has an α-chitin structure with a crystallinity of 84.5%. Thus, microwave heating can be used as an effective pretreatment method for mineral and protein removal in chitin extraction from crustaceans.