Note: a the main wave numbers obtained in the present study; b the main wave numbers reported in the literature [30-34]; c functional groups; d molecules of the functional groups. CWM, cell wall material; CDTA, 2-cyclohexanediamine-N,N,N’,N ’-acetic acid; C, cellulose; P, pectin; XG, xyloglucan.
The effect of different extraction conditions (solid-liquid ratio, enzyme concentration, enzyme hydrolysis temperature, and enzyme hydrolysis time) on FT-IR spectra of celluloses are presented in Fig. 2. The main characteristic wave numbers of cellulose remained unchanged under different extraction conditions, but the absorbance, which denotes the content of characteristic wave numbers, varied significantly. Examples of FT-IR spectra of cellulose under different solid- liquid ratio are shown in Fig. 2a, cellulose had same characteristic wave numbers. However, characteristic bands of celluloses at solid- liquid ratio 1:3, 1:4, and 1:5 were sharper and more intensive compared to that at solid- liquid ratio 1:2. The solid- liquid ratio, enzyme concentration, enzyme hydrolysis temperature, and enzyme hydrolysis time exhibited a different degree of influence on the cellulose characteristic wave numbers, and changes of characteristic bands were corresponding to the acting sites of Viscozyme® L on cellulose. Similar results were observed for hemicellulose, CDTA-soluble pectin, and Na2CO3-soluble pectin (Figs.3-5).