Extraction of Chitin from Giant Tiger Prawn (Penaeus monodon) Shrimp Shell Using Deep Eutectic Solvents and Citric Acid

Chitin, a natural biomass resource, has shown great promise for a wide range of applications because of its high bioactivity. This study evaluated the effectiveness of deep eutectic solvents (DESs) mixed with citric acid as a method for extracting chitin from the shells of giant tiger prawn shrimps (Penaeus monodon). The purity and physicochemical properties of the extracted chitin were compared with those obtained using the traditional chemical extraction method and commercial chitin. The results showed that the highest chitin purity (99.22%) was achieved when choline chloride-glycerol (ChCl–Gl) was used in a 1:2 molar ratio with a citric acid content of 5% w/v (CG2-5%). Additionally, the extracted chitin had a molecular weight of 3.75 × 105 Da and a crystallinity index of 81.34%, which was slightly higher than that of chitin extracted using the conventional method (3.24 × 105 Da and 73.59%). However, there was no significant difference between chitin extracted by CG2-5% and commercial chitin. This suggests that the structure of the biopolymer remained intact following the CG2-5% extraction process. The α-chitins in tiger prawn shrimp shells, as confirmed by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray Diffraction Analysis (XRD), are analogous to commercial shrimp chitin. These results, achieved without employing potentially harmful chemicals, demonstrate that CG2-5% can efficiently enhance chitin extraction from diverse raw biomass sources without jeopardizing the polymer's structural stability.