In the present study, the tannins from stem and root barks of Tessmannia burttii Harms (Caesalpiniaceae), a plant species abundantly growing in Tanzania and other parts of Africa, were investigated for their suitability in hides tanning. Tannin powder was extracted at selected temperatures (30, 50 and 80 °C) and the influence of each temperature on the crosslinking capacity was evaluated. The interaction mechanism between hide powder collagen and the tannins was studied by Differential Scanning Calorimetry (DSC), trinitrobenzensulfonic (TNBS) acid assay and amino acid hydrolysis methods. Extraction temperatures showed low influence on crosslinking capacity of the tannins. However, extract obtained at 50 °C exhibited best performance in terms of gap size between Tonset and Tpeak. The stem bark extract yield was higher than that from the root bark, but both were within the recommended ranges. The tannin content (61%) of T. burttii stem bark extract was above recommended value (10%), whereas its total phenolic content and total flavonoic content were found to be above that of commercial Acacia mearnsii tannin. The study of cross-linking parameters as a function of pH showed cross-linking to occur via a covalent mechanism at the basic amino groups. However, the bonds were not resistant to acid hydrolysis. The observed interaction mechanism indicated that tannins from stem and root barks of T. burttii belong to the condensed tannin, similar to A. mearnsii (black wattle), a commercial tannin source that was used in this study as a reference. Findings from this study depict that T. burttii extracts are auspicious eco-friendly alternative source of vegetable tannins to overcome the use of chromium salts in the leather industry.

中文翻译：

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Tessmannia burttii提取物的鞣制能力：皮革行业潜在的环保鞣革剂

在本研究中，对坦桑尼亚和非洲其他地区大量生长的特斯曼尼亚草（Tesmannia burttii Harms，Caesalpiniaceae）茎和根皮中的单宁进行了研究，探讨其在皮革鞣制中的适用性。在选定的温度（30、50和80°C）下提取单宁粉，并评估每种温度对交联容量的影响。通过差示扫描量热法（DSC），三硝基苯磺酸（TNBS）酸测定法和氨基酸水解法研究了生皮粉胶原蛋白与单宁的相互作用机理。提取温度对单宁的交联能力影响很小。然而，就Tonset和Tpeak之间的间隙大小而言，在50°C下获得的提取物表现出最佳性能。茎皮提取物的产量高于根皮，但两者均在建议范围内。burttii茎皮提取物的单宁含量（61％）高于建议值（10％），而其总酚含量和总黄酮含量高于商业金合欢（Acacia mearnsii）单宁。对交联参数随pH的影响的研究表明，交联是通过碱性氨基上的共价机制发生的。但是，这些键不耐酸水解。观察到的相互作用机理表明，来自伯氏螺旋藻茎和根皮的单宁属于缩合单宁，类似于A. mearnsii（黑荆），该研究中使用的商业单宁来源作为参考。这项研究的结果描述了T。