Institute of Industrial Fermentations, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
J Agric Food Chem. 2009 Nov 25;57(22):10590-9. doi: 10.1021/jf901391a.
In the present study, the flavan-3-ol composition and antioxidant capacity of roasted skins obtained from the industrial processing of three commonly consumed tree nuts (i.e., peanuts, hazelnuts, and almonds), as well as fractions containing low and high molecular weight (LMW and HMW) flavan-3-ols, were studied with the aim of assessing their potential as a source of flavonoids. Roasted peanut and hazelnut skins presented similar total phenolic contents, much higher than that of almond skins, but their flavan-3-ol profiles, as determined by LC-ESI-MS and MALDI-TOF MS, differed considerably. Peanut skins were low in monomeric flavan-3-ols (19%) in comparison to hazelnut (90%) and almond (89%) skins. On the other hand, polymeric flavan-3-ols in peanut and almond skins occurred as both A- and B-type proanthocyanidins, but in peanuts the A forms (up to DP12) were predominant, whereas in almonds the B forms (up to DP8) were more abundant. In contrast, hazelnuts were mainly constituted by B-type proanthocyanidins (up to DP9). The antioxidant capacity as determined by various methods (i.e., total antioxidant capacity, ORAC, DPPH test, and reducing power) was higher for whole extracts from roasted hazelnut and peanut skins than for almond skins; however, the antioxidant capacities of the HMW fraction of the three types of nut skins were equivalent despite their different compositions and DPs. Nevertheless, the large variation in flavan-3-ol concentration, structural composition, type of interflavan linkage, and DP found among the three types of nut skins suggests large difference in their expected in vivo biological activities.
在本研究中，研究了工业加工三种常见食用坚果（即花生、榛子和杏仁）的烤果皮中的黄烷-3-醇组成和抗氧化能力，以及含有低和高分子量（LMW 和 HMW）黄烷-3-醇的馏分，目的是评估它们作为类黄酮来源的潜力。烤花生和榛子皮的总酚含量相似，远高于杏仁皮，但它们的黄烷-3-醇图谱通过 LC-ESI-MS 和 MALDI-TOF MS 测定，差异很大。与榛子（90%）和杏仁（89%）皮相比，花生皮中的单体黄烷-3-醇含量较低（19%）。另一方面，花生和杏仁皮中的聚合黄烷-3-醇既以 A 型和 B 型原花青素的形式存在，但在花生中 A 型（最多 DP12）占主导地位，而在杏仁中 B 型（最多 DP8）更丰富。相比之下，榛子主要由 B 型原花青素（最多 DP9）组成。通过各种方法（即总抗氧化能力、ORAC、DPPH 试验和还原能力）测定的抗氧化能力，烤榛子和花生皮的全提取物高于杏仁皮；然而，尽管三种类型的坚果皮的组成和 DP 不同，但 HMW 馏分的抗氧化能力相当。然而，三种类型的坚果皮中的黄烷-3-醇浓度、结构组成、二聚体键类型和 DP 存在很大差异，表明它们在体内预期的生物活性存在很大差异。
