Natural Enzymes from Germinated Winter Wheat (Triticum aestivum L) and Buckwheat ( Fagopyrum esculentum) for Chitin Isolation from Shrimp Shells

Abstract

Abstract The industrial approach for chitin extraction from crustaceans' shells involves chemical methods using a large amount of acid and alkaline. Using natural protease in combination with chemicals can reduce the use of the chemicals in extracting chitin. Crude enzymes from germinated winter wheat (Triticum aestivum) and buckwheat (Fagopyrum esculentum) were applied in the deproteinization step during chitin isolation from shrimp shells. Crude enzymes extracted from germinated winter wheat and buckwheat exhibited proteolytic activity of approximately 0.49 U/mL and 0.46 U/mL, respectively. Using these crude enzymes separately to remove protein from demineralized shrimp shells yielded 30.31 ± 5.31% and 29.15 ± 3.99% chitin, respectively. Functional groups and crystallinity index of chitin isolated with winter wheat or buckwheat enzymes were compared with commercially available chitin and chemical-isolated chitin through Fourier Transform Infrared Spectroscopy (FTIR) analysis and x-ray diffraction analysis. The characteristic functional groups observed were amide I, amide II, amide III, asymmetric stretching of the C-O-C bridge, O-H stretching, NH stretching and asymmetric CH stretching. The crystallinity index for commercial chitin, chemical-isolated chitin, wheat extract- and buckwheat extract-isolated chitin were 86.49%, 88.74%, 88.82% and 75.87%, respectively. Buckwheat extract-isolated chitin, which was deacetylated with lower crystallinity, warrants further investigation. Natural enzymes from winter wheat and buckwheat to remove protein from shrimp shells can be a more environment-friendly method to valorize shrimp shells as a chitin source.