In this study, an alkali freeze-thaw pretreatment protocol was investigated to inhibit the enzymatic hydrolysis of chitin in No-Acetylglucosamine (GlcNAc) in high concentrations. The optimal conditions for the alkaline freeze-thaw treatment of chitin were an alkali concentration of 8% (w / v), a temperature of -25 ° C, two freeze-thaw cycles in 12 h and a substrate concentration of 4. determined% (w / v). This treatment resulted in the chitin powder taking on a visible fibrillar structure, whereby scanning electron microscopy and Brunauer-Emmett-Teller analysis showed that the surface of the chitin changed from a dense structure to a nanofibrillar structure (diameter 30-50 nm) with enlarged surfaces the treatment. In addition, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, X-ray diffraction and intrinsic viscosity analysis showed that the crystallinity, molecular weight and thermal stability of chitin decreased upon pretreatment without changing the chemical structure or deacetylation. Interestingly, after the precipitation of chitin, the alkali solution can be easily recovered above Boiling and centrifugation, and the recovered alkali aqueous solution can be reused without reducing the effect of the subsequent treatment. In addition, the GlcNAc concentrations from the enzymatic fed-batch hydrolysis of chitin treated with KOH and NaOH can reach up to 75 g L. to reach-1 and 68 g L-1 over 18 h or thus this work shows a clean, sustainable and efficient method to convert chitin into GlcNAc.

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