Marles M A Susan, Coulman Bruce E, Bett Kirstin E
Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada S7N 5A8.
J Agric Food Chem. 2008 Nov 12;56(21):9797-802. doi: 10.1021/jf800888r. Epub 2008 Oct 8.
Legumes with high concentrations of condensed tannin (pinto bean [Phaseolus vulgaris L.], sainfoin [Onobrychis viciifolia Scop.], and big trefoil [Lotus uliginosus Hoff.]), were compared to a selection of forages, with low or zero condensed tannin (smooth bromegrass [ Bromus inermis Leyss], Lotus japonicus [Regel] K. Larsen, and alfalfa [Medicago sativa L.]), using four methods to estimate fiber or lignin. Protocols were validated by using semipurified condensed tannin polymers in adulteration assays that tested low-lignin tissue with polyphenolic-enriched samples. The effect on lignin assay methods by condensed tannin concentration was interpreted using a multivariate analysis. There was an overestimation of fiber or lignin in the presence of condensed tannin in the acid detergent fiber (ADF) and Klason lignin (KL) assays compared to that in the thioglycolic acid (TGA) and acid detergent lignin (ADL) methods. Sulfite reagents (present in TGA lignin method) or sequential acidic digests at high temperatures (ADF followed by ADL) were required to eliminate condensed tannin. The ADF (alone) and KL protocols are not recommended to screen nonwoody plants, such as forages, where condensed tannin has accumulated in the tissue.
将高浓度缩合单宁的豆类（斑豆[菜豆属菜豆]、红豆草[红豆草属红豆草]和大百脉根[百脉根属湿地百脉根]）与低缩合单宁或零缩合单宁的一些草料（无芒雀麦[无芒雀麦属无芒雀麦]、日本百脉根[百脉根属日本百脉根]和苜蓿[苜蓿属紫花苜蓿]）进行比较，使用四种方法来估算纤维或木质素。通过在掺假试验中使用半纯化的缩合单宁聚合物来验证实验方案，该试验用富含多酚的样品检测低木质素组织。使用多变量分析来解释缩合单宁浓度对木质素测定方法的影响。与巯基乙酸（TGA）法和酸性洗涤木质素（ADL）法相比，在酸性洗涤纤维（ADF）和克拉斯森木质素（KL）测定中，缩合单宁的存在会导致纤维或木质素的高估。需要亚硫酸盐试剂（TGA木质素法中存在）或高温下的连续酸性消化（ADF后接ADL）来消除缩合单宁。不建议使用ADF（单独）和KL方案来筛选非木质植物，如组织中积累了缩合单宁的草料。
