Largely produced agri-food byproducts represent a sustainable and easily available source of phenolic compounds, such as lignins and tannins, endowed with potent antioxidant properties. We report herein the characterization of the antioxidant properties of nine plant-derived byproducts. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated the superior activity of pomegranate peels and seeds, grape pomace and pecan nut shell. An increase in the antioxidant potency was observed for most of the waste materials following a hydrolytic treatment, with the exception of the condensed tannin-rich pecan nut shell and grape pomace. UV-Vis and HPLC investigation of the soluble fractions coupled with the results from IR analysis and chemical degradation approaches on the whole materials allowed to conclude that the improvement of the antioxidant properties was due not only to removal of non-active components (mainly carbohydrates), but also to structural modifications of the phenolic compounds. Parallel experiments run on natural and bioinspired model phenolic polymers suggested that these structural modifications positively impacted on the antioxidant properties of lignins and hydrolyzable tannins, whereas significant degradation of condensed tannin moieties occurred, likely responsible for the lowering of the reducing power observed for grape pomace and pecan nut shell. These results open new perspectives toward the exploitation and manipulation of agri-food byproducts for application as antioxidant additives in functional materials.

中文翻译：

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农业食品副产品的抗氧化特性和水解处理的特定促进作用。


大量生产的农业食品副产品是木质素和单宁等酚类化合物的可持续且易于获取的来源，具有强大的抗氧化特性。我们在此报告了九种植物副产品的抗氧化特性的表征。 2,2-二苯基-1-三硝基苯肼 (DPPH) 和铁还原/抗氧化能力 (FRAP) 测定表明石榴皮和种子、葡萄渣和山核桃壳具有卓越的活性。除浓缩的富含单宁的山核桃壳和葡萄果渣外，大多数废料经过水解处理后，其抗氧化效力均有所增加。对可溶部分的 UV-Vis 和 HPLC 研究，结合 IR 分析结果和对整个材料的化学降解方法，可以得出这样的结论：抗氧化性能的提高不仅是由于非活性成分（主要是碳水化合物）的去除。 ，还可以对酚类化合物进行结构修饰。对天然和仿生模型酚醛聚合物进行的平行实验表明，这些结构修饰对木质素和可水解单宁的抗氧化特性产生积极影响，而缩合单宁部分发生显着降解，可能是葡萄渣和可水解单宁的还原能力降低的原因。山核桃壳。这些结果为开发和操纵农业食品副产品作为功能材料中的抗氧化添加剂的应用开辟了新的视角。