کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1384252 1500899 2012 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Structural characterization of hemicelluloses fractionated by graded ethanol precipitation from Pinus yunnanensis
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Structural characterization of hemicelluloses fractionated by graded ethanol precipitation from Pinus yunnanensis
چکیده انگلیسی

Fractionation of hemicelluloses from delignified Pinus yunnanensis was carried out with KOH/H3BO3 solution followed by graded precipitation in 15%, 60%, and 90% (v/v) ethanol solutions, respectively. Chemical compositions, physicochemical properties, and structures of the precipitated hemicellulosic fractions were elucidated by a combination of sugar analysis, GPC, FT-IR, and 1H, 13C and 2D HSQC NMR spectroscopy. Sugar analysis showed that the hemicellulosic fraction precipitated by 15% ethanol solution (H1) had a predominance of xylose (58.52%), while mannose was the major sugar component in the hemicellulosic fractions precipitated by 60% (H2) and 90% (H3) ethanol solutions. GPC results revealed that the hemicelluloses precipitated by low concentration of ethanol solutions had higher weight-average molecular mass (50,090–79,840 g/mol) than those obtained in the high concentration of ethanol solutions (16,500 g/mol). The fraction precipitated by 60% ethanol solution (H2) was composed of d-galactose, d-glucose and d-mannose in a ratio of approximately 1:1:3.5. Structural determination indicated that the hemicellulosic fraction (H2) had a main structure of (1→4)-linked β-glucomannans backbone with (1→6)-linked α-d-galactose as a side chain attached to C-6 of mannose units. In addition, this fraction also contained minor amounts of xylans.

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► Hemicelluloses were extracted with KOH/H3BO3 followed by graded precipitation.
► Increasing ethanol concentration led to a decrease in molecular weight.
► Hemicelluloses were mainly composed of (1→4)-linked β-glucomannans.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Research - Volume 352, 1 May 2012, Pages 159–165
نویسندگان
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