| Cyclodextrins are important compounds which have widespread application in industry and great significance in scientific research. Determination method of cyclodextrins, effects of reaction condition and pretreatment of substrate on the production of cyclodextrins have been investigated in this paper. A nonsolvent method was adopted to produce cyclodextrins, trying to get the influence law of preparation technology on the composition of the products.First of all, further improvement of the determination methods ofα-,γ-cyclodextrin were investigated repectively, and the methods coule be used when the concentration ofα-,γ-cyclodextrin were between 0 g/L and 0.3 g/L. The optimal determining condition ofα-cyclodextrin was as follow: wavelength was 507 nm, pH was 1.6, temperature was 16℃, concentration of methyl orange was 0.1 mmol/L. The optimal determining condition ofγ-cyclodextrin was as follow: wavelength was 640 nm, pH was 4.1, at room temperature, concentration of bromocresol green was 5 mmol/L. The inclusion complex formation of bromocresol green withγ-cyclodextrin was studied by using UV-Vis, continuous variation plot, thermodynamics, molecular modeling, nuclear magnetic resonance and infrared spectrum methods. The determining principle ofγ-cyclodextrin was as follow: the inhibiting coloring group of bromocresol green was included inγ-cyclodextrin, thus the absorbing spectra became strong.The effects of pH, temperature, concentration of substrate, reaction time, reaction medium and amount of enzyme on the production of cyclodextrins were determined by single factor experiment using corn dextrin (DE=5) as the substrate. The yield of cyclodextrin reached highest when the concentration of the substrate was 250 g/L, the amount of enzyme was 4 U/g and the concentration of CaCl2 was 40 mmol/L. The change in composition of the products was not significant. The effects of pH and reaction time on the production of cyclodextrins were different. The interactional effects of pH, temperature and reaction time on the production of cyclodextrins were investigated by response surface analysis, and the best production conditions were as follow:α-cyclodextrin: pH was 7.5, temperature was 65℃, reactional time was 3 h;β-cyclodextrin: pH was 8.5, temperature was 65℃, reactional time was 12 h;γ-cyclodextrin: pH was 7.0, temperature was 65℃, reactional time was 24 h.The effects of different substrates on the production of cyclodextrins were compared by using corn starch, tapioca starch, potato starch and waxy corn starch. The highest yield of cyclodextrins was got by using the tapioca starch as the substrate. Besides, the compositon of the products was different with different substractes. The effects of different pretreatments of starch on the production of cyclodextrins were investigated by using tapioca starch as the substrate, and the best result was got from enzyme hydrolysis among enzyme hydrolysis, acid hydrolysis and oxidation.Mother liquor got from solvent method was the reaction solution residue from whichβ-cyclodextrin was separated. The compositon of the mother liquor was analyzed. The content of total sugar was found to be the main component. The percent ofα-,β-,γ-cyclodextrin was 1.36%, 24.72%, 0.25%, respectively, the proportion of them was 5:94:1. However, the proportion ofα-,β-,γ-cyclodextrin was 16:74:10 when using nonsolvent method. The results showed that the solvent improved the yield ofβ- cyclodextrin, and at the same time reduced the yield ofα-cyclodextrin andγ-cyclodextrin. |
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