机械粉碎对高粱秆微观结构及酶解效果的影响

EFFECTS OF MECHANICAL GRINDING ON MICRO-STRUCTURE OF SORGHUM STRAW AND ENZYMATIC HYDROLYSIS

采用扫描电镜(SEM)、傅立叶变换红外光谱(FTIR)和X射线衍射以及酶水解实验对不同粒径范围(300～450μm、125～150μm、97～105μm和330～420nm)的高粱秆进行分析。结果表明:随着粉碎程度增大,高粱秆中纤维素与酶有效接触点增多,但由于团聚现象发生,导致酶有效接触点增多并不与粒度减小成线性关系;粉碎还导致高粱秆结晶度降低,结品度从粒径范围300～450μm时的0.6105降低到330～420nm时的0.2397,并对结晶区晶型结构和高粱秆物质结构有影响,但是对高粱秆成分没有影响。这些都导致在后续的酶解糖化实验中还原糖浓度随酶解时间和粉碎程度的增大而增大,其中粒径范围330～420nm的高粱秆在酶解180h时仍保持较大的酶解转化率。

Micro-structure changes of sorghum straw at different size ranges （300-450μm, 125-150μm, 97-105μm and 10-420nm） were determined using scanning eletron microscope （SEM）, Fourier transform infrared （FTIR） spectroscopy, X-ray diffractometer （XRD） and the experiment of enzymitic hydrolysis. The results showed that the effective contact point with the enzyme of cellulose increased with the increasing of grinding degree, but increased enzyme effective contact point with the enzyme were not a linear relationship with particle size reduction because of reunion took place. Grinding also resulted in lower crystallinity of sorghum straw, crystallinity values of sorghum straw dropped from 0. 6105 at size ranges 300 - 450μm to 0. 2397 at size ranges 10 - 420nm, the crystalline properties and the tracture of sorghum straw also changed as indicated by XRD results as well, but no changes had happened to compositions of sorghum straw. All these caused that reducing sugar concentrations produced by enzymatic saccharification improved greatly with hydrolysis time longer and smash degree greater, enzymatic conversion rate of sorghum straw at size ranges 10 - 420nm also remained large at 180h.