Liu C F, Xu F, Sun J X, Ren J L, Curling S, Sun R C, Fowler P, Baird M S
State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510641, China.
Carbohydr Res. 2006 Nov 27;341(16):2677-87. doi: 10.1016/j.carres.2006.07.008. Epub 2006 Aug 24.
In this study, we investigated the physicochemical properties of the cellulosic preparations obtained from both untreated perennial ryegrass leaves and de-juiced leaves. It was found that treatment at 22 degrees C with 18% NaOH and 18% KOH for 2h, and 10% NaOH and 10% KOH for 16 h yielded 28.2%, 28.8%, 22.7%, 23.4%, respectively, of 'cellulose' residue from untreated ryegrass leaves and 35.7%, 36.8%, 32.8% and 34.6%, respectively, from the de-juiced leaves. For each cellulosic fraction, the glucose content was 71.6%, 69.6%, 67.8%, 66.7%, 69.7%, 68.6%, 63.9% and 61.7%, respectively. The structure of the cellulose samples was examined using FTIR and CP/MAS (13)C NMR spectroscopy and X-ray diffraction. The cellulosic preparations were free of bound lignin except for noticeable amounts of residual hemicelluloses (28.4-38.3%), and had intrinsic viscosities between 275.1 and 361.0 mL/g, along with molecular weights from 144,130 to 194,930 g/mol. This study found that the cellulose samples isolated from both de-juiced ryegrass leaves and the untreated leaves had a much lower percent crystallinity (33.0-38.6%) than that from wood-based fibres (60-70%) and had much shorter fibres (0.35-0.49 mm) than those of either cereal straws, bagasse or wood. In addition, a partial disruption of the hydrogen bonds and microfibrils may occur during the de-juicing process by mechanical activity, which results in a decreased cellulose crystallinity and fibre length. These findings are significant in relation to hydrolysing ryegrass cellulose for bio-ethanol production.
在本研究中，我们调查了从未经处理的多年生黑麦草叶片和去汁叶片中获得的纤维素制剂的物理化学性质。结果发现，在22℃下用18%的NaOH和18%的KOH处理2小时，以及用10%的NaOH和10%的KOH处理16小时，从未经处理的黑麦草叶片中分别得到28.2%、28.8%、22.7%、23.4%的“纤维素”残渣，而去汁叶片中分别得到35.7%、36.8%、32.8%和34.6%。对于每个纤维素级分，葡萄糖含量分别为71.6%、69.6%、67.8%、66.7%、69.7%、68.6%、63.9%和61.7%。使用傅里叶变换红外光谱（FTIR）、交叉极化/魔角旋转（13）C核磁共振光谱和X射线衍射对纤维素样品的结构进行了检查。纤维素制剂除了含有大量残留半纤维素（28.4 - 38.3%）外，不含结合木质素，其特性粘度在275.1至361.0 mL/g之间，分子量在144,130至194,930 g/mol之间。本研究发现，从去汁黑麦草叶片和未经处理的叶片中分离出的纤维素样品的结晶度百分比（33.0 - 38.6%）远低于木基纤维（60 - 70%），且纤维长度（0.35 - 0.49毫米）比谷物秸秆、甘蔗渣或木材的纤维短得多。此外，在去汁过程中，机械活动可能会导致氢键和微纤丝部分破坏，从而导致纤维素结晶度和纤维长度降低。这些发现对于将黑麦草纤维素水解用于生物乙醇生产具有重要意义。
