Studies On The Extraction Technology Of Chitosan From The Mycelia Of Rhizopus Oryzae

This paper researched the extraction and preparation technology of chitosan from waste mycelia of Rhizopus oryzae by L-lactic acid industrial fermentation. The pretreatment method of mycelia, technological conditions of deproteinization with alkali fragmentation,deacetylation,extraction with dilute acetic acid and purification with ethanol were investigated. An optimized technology of extracting the chitosan from Rhizopus oryzae mycelia was established, and the medium-scale experiment was processed on the base of this technology, besides, the quantitative and qualitative analysis of the product of medium-scale experiment were studied.The main extraction process is: pretreatment on the Rhizopus oryzae mycelium→deproteinization with dilute alkali solution→washing filter residue to neutral→deacetylation with concentrated alkali solution→washing filter residue to neutral→extraction with acetic acid→collecting filtrate→adjusting pH to 10.0→washing precipitation to neutral→washing precipitation with ethanol→vacuum drying→the product of chitosan.To research the effect of different factors (including alkali solution concentration, treatment time, treatment temperature) on deproteinization of mycelium cell, the orthogonal test was adopted to optimize the technological condition of deproteinization with alkali solution. The results show that: the alkali solution concentration influence prominently the deproteinization rate in the process of deproteinization among the influential factors, next came treatment temperature and treatment time. The optimal technological conditions of deproteinization with dilute alkali solution has been fixed as follows: sodium hydroxide 2%, treatment temperature 60℃, treatment time 4h.The deproteinization rate was up to 85%.The orthogonal test and single factor test were adopted to optimize the technological condition of deacetylation, and relative technical parameters (including alkali solution concentration, treatment time, treatment temperature) were determined. The results show that: the alkali solution concentration was the most important factor which affect the degree of deacetylation, next came treatment temperature and treatment time. The optimal technological conditions of deacetylation has been established as follows: sodium hydroxide 20%, treatment temperature 120℃, treatment time 2 h. The degree of deacetylation was up to 90%.The single factor test were adopted to research the technological conditions of chitosan extraction with acetic acid. To determine the effect of acid concentration, extraction temperature and extraction time on the extraction result, the yield and viscosity value of the product were considered as the indication, the result shows that: The optimal technological conditions of acid extraction is, acetic acid 2%, extraction temperature 60℃.According to above optimized technical parameters, we conducted a medium-scale experiment. Furthermore, the quantitative and qualitative analysis of the chitosan product were carried out, the results showed: the IR spectrogram of the extracted product can match the chitosan standard spectrogram, various indication can meet national food grade standard SC/T3403-2004, The purity of chitosan product is 90.18% with a yield ratio accounted for 9.2% of the dry weight of mycelia.