通过扫描电镜、基础理化成分、相对分子质量分布、氨基酸组成、紫外光谱和圆二色光谱对小麦低聚肽结构特征进行分析，从羟基自由基清除能力、DPPH自由基清除能力、ABTS自由基清除能力和氧自由基吸收能力（ORAC）4个方面对其体外抗氧化活性进行考察。结果表明，小麦低聚肽具有明显的球体颗粒状，表面有不规则褶皱和气孔，蛋白质和肽含量分别为95.86%、83.74%（均以干基计），分子质量1000 u以下的组分占92.22%，必需氨基酸和疏水性氨基酸含量分别为20.46%、33.38%，在270 nm波长处有最大吸收峰。二级结构以多种构象并存，α-螺旋、平行式β-折叠、反平行式β-折叠、β-转角和无规卷曲含量分别为5.83%、3.14%、37.57%、20.32%和33.14%。小麦低聚肽对羟基自由基和DPPH自由基的半抑制浓度（IC50值）分别为9.62、1.54 mg/mL，ABTS自由基清除能力为3.53 mmol Trolox/g，ORAC值为1035.52 μmol Trolox/g。因此，小麦低聚肽具有较强的抗氧化能力，为其在抗氧化功能食品的开发利用提供一定的理论依据。

The structural characteristics of wheat oligopeptides were elucidated using scanning electron microscopy imaging as well as analyses of their basic physicochemical composition, relative molecular weight distribution, amino acid composition, and ultraviolet and circular dichroism spectra. The in vitro antioxidative activity of the oligopeptides was investigated by determining their oxygen radical absorbance capacity (ORAC) and their abilities to scavenge hydroxyl, DPPH, and ABTS free radicals. The wheat oligopeptides were in the form of spherical granules and had irregular folds and pores on the surface. Their protein and peptide contents were 95.86% and 83.74% (both on a dry basis), respectively, and 92.22% of the components had a molecular weight of less than 1000 u. Their contents of essential amino acids and hydrophobic amino acids were 20.46% and 33.38%, respectively. The maximum absorption peak was at 270 nm. The α-helix, parallel β-fold, antiparallel β-fold, β-turn, and random coil contents of the oligopeptides were 5.83%, 3.14%, 37.57%, 20.32%, and 33.14%, respectively, indicating the coexistence of multiple secondary structures. The IC50 values of wheat oligopeptides for hydroxyl and DPPH free radicals were 9.6 and 1.5 mg/mL, respectively. Moreover, their ABTS free radical-scavenging activity was 3.53 mmol Trolox/g and their ORAC was 1035.52 μmol Trolox/g. In summary, these findings indicating the strong antioxidative capacity of wheat oligopeptides provide a theoretical basis for their use in the development of antioxidant-containing foods.

国家重点研发计划项目（2016YFD0400604）；国家自然科学基金项目（31671963）；北京市科技创新基地培育与发展工程专项（Z191100002819001）