Extraction of chitin and chitosan from commercial mushrooms waste: a comparative study on the yield of chitin and chitosan from pleurotus ostreatus and agaricus bisporus mushrooms
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Chitin and Chitosan from two species of mushrooms Pleurotus Ostreatus and Agaricus Bisporus were extracted through three procedural steps that are 1. deprotenisation where alkaline soluble proteins are removed using 4 M NaOH solution and refluxing with ethanoic acid to remove acid soluble proteins, 2. Decolourisation was done using 1% KMnO4 followed by 1% oxalic acid, and then 3. Deacetyation of chitin using 60% NaOH solution for 2 hours. Deacetyation is done to remove the acetyl groups in chitin and convert ß(1→4)- N-acetyl-Dglucosamine to α(1→4) linked 2-amino-2-deoxy-ß-D-glucopyranose (Chitosan). The effect of different parameters was investigated in the deproteinisation stage as follows:-temperature was investigated by using 80 ºC and then 100 ºC using 4 M NaOH for 3 hours, with 80 ºC maintained using a water bath, concentrations of 2 M and 4 M NaOH were used at 100 ºC for 3 hours, time of boiling with 4 M NaOH at 100 ºC was investigated at 1 hour and 3 hours. Crude Chitin produced using the different parameters was analysed using the FT IR. A yield of 11.6% was produced for Pleurotus ostreatus Chitin and 13.3% for Agaricus Bisporus Chitin. The corresponding Chitosan yields were 73% and 74.2% respectively, for the product from 4M NaOH, 100 ºC, 3 hours. Best Chitin quality was obtained from Sample B (agaricus bisporus) in terms of quality and resolution of FTIR spectra although it had an off white colour as compared to the sample A (pleurotus ostreatus). The bulk density was a bit lower for sample B as compared with sample A , that is, 0.344 g/cm3 and 0.400 g/cm3 respectively. The FTIR spectra gave the expected functional groups for both Chitin and Chitosan under all the conditions/parameters tested. Functional groups that are common to both Chitin and Chitosan like the OH bend, C-O-C bridge, CH and C-C stretches were observed, however for Chitin the C=O stretch was also obsevered which confirmed quality of product. The NH2 stretch also confirmed the quality of Chitosan produced. These results concur with theory and literature.