Effect of sub- and supercritical water treatments on the physicochemical properties of crab shell chitin and its enzymatic degradation

Abstract

This study examined the effects of sub-and supercritical water pretreatments on the physicochemical properties of crab shell α-chitin and its enzymatic degradation to obtain N,N'-diacetylchitobiose (GlcNAc)2. Following sub-and supercritical water pretreatments, the protein in the crab shell was removed and the residue of crab shell contained α-chitin and CaCO3. Prolonged pretreatment led to α-chitin decomposition. The reaction of pure α-chitin in sub-and supercritical water pretreatments was investigated separately; we observed lower mean molecular weight and weaker hydrogen bonds compared with untreated α-chitin.(GlcNAc)2 yields from enzymatic degradation of subcritical (350C, 7 min) and supercritical water (400C, 2.5 min) pretreated crab shell were 8% and 6%, compared with 0% without any pretreatment. This study shows that sub-and supercritical water pretreatments of crab shell provide to an alternative method to the use of acid and base for decalcification and deproteinization of crab shell required for (GlcNAc)2 production.

Parameters of hydrothermal gelation of chitin nanofibers determined using a severity factor

“…The degree of N-acetylation of the original -ChNFs was 95%, and their deacetylation did not occur after the hydrothermal treatment. In previous studies, the decomposition of the chitin chemical structure through its deacetylation was observed after the hydrothermal treatment at temperatures above 300 °C (Osada et al 2012(Osada et al , 2013(Osada et al , 2015Aida et al 2014); however, the hydrothermal treatment at temperatures less than 200 °C conducted in this study did not decrease the degree of Nacetylation. The obtained FT-IR spectra indicate that the chemical structure of -ChNFs was not affected by the hydrothermal gelation.…”

Cycloamination strategies for renewable N-heterocycles

“…D-glucosamine (the monomer) and/or N,N′-diacetylchitobiose (the dimer) with yields of no more than 8%. 346,347 At relatively high temperatures of (200 to 260)°C, treatment of proteins with HTW and fast heating rates (135 to 180) K s −1 inhibits initial protein aggregation that occurs during the reaction process at slow heating rates (ca. 0.25 K s −1 ), affording highmolecular-weight peptides (1500 to 8300) Da as dominant products with the transformation advantageously occurring as random-scission.…”

Optimization of extraction of chitin from procambarus clarkia shell by Box-Behnken design

“…Chitin owns excellent biological efficacy and diverse applications in different fields, such as textile industry, feed industry, medical materials, environmental protection, and so on [1]. For example, chitin is utilized for treating wastewater as adsorbents and flocculants [2,3], and is vital for artificial skin, artificial dialysis membrane and artificial blood vessels in medical materials field [4,5]. The shell of arthropod and fungus are rich in chitin.…”