Department of Food Science, University of Manitoba, Manitoba, Canada.
J Agric Food Chem. 2009 Aug 26;57(16):7543-51. doi: 10.1021/jf901074b.
The health benefits of whole grain consumption have been attributed to their content of complex carbohydrates, vitamins, minerals, and other phytochemical constituents. Wild rice is a whole grain finding applications in gourmet foods due to its nutritional value and unique taste. However, little is known about its antioxidant properties and phytochemical components. The objectives of this study were to evaluate the antioxidant properties of wild rice. Eleven commercial wild rice samples (raw, mixed, and processed) were extracted with acetone and fractionated using a Sephadex LH-20 column. 2,2-Diphenyl-1-picrylhydrazyl radical (DPPH()) scavenging activity, oxygen radical absorbance capacity (ORAC), and total phenolic content were evaluated to determine the antioxidant properties of wild rice. The antioxidant activity of wild rice was found to be 30 times greater than that of the control white rice. Significant differences (p < 0.05) in antioxidant activities were found among raw, mixed, and processed samples. For raw samples, DPPH() radical scavenging activities and ORAC values ranged from 611 to 917 micromol of Trolox equivalent (TE)/100 g and from 4069 to 6064 micromol of TE/100 g, respectively. For mixed and processed wild rice, DPPH(*) radical scavenging activities were 373 and 441 micromol of TE/100 g, respectively. The corresponding ORAC values were 2284 and 2557 micromol of TE/100 g. Total phenolic content (TPC) of raw wild rice varied from 2472 to 4072 mg of ferulic acid equivalent (FAE)/kg, higher than that of the mixed sample (1460 mg of FAE/kg) and processed sample (2076 mg of FAE/kg). TPC was highly correlated with total antioxidant activity of wild rice (r = 0.92). Tandem mass spectrometric techniques revealed the antioxidants identified in wild rice to be flavonoid glycosides (diglucosyl apigenin, glucosyl-arabinosyl apigenin, and diarabinosyl apigenin) in factions 2 and 3 and flavan-3-ols (catechin, epicatechin, and oligomeric procyanidin) in fractions 4 and 5.
全谷物消费的健康益处归因于其复杂碳水化合物、维生素、矿物质和其他植物化学成分的含量。野生稻是一种全谷物，由于其营养价值和独特的口感，在美食食品中得到了应用。然而，人们对其抗氧化特性和植物化学成分知之甚少。本研究的目的是评估野生稻的抗氧化特性。用丙酮提取 11 种商业野生稻样品（生的、混合的和加工的），并用 Sephadex LH-20 柱进行分离。用 2,2-二苯基-1-苦基肼基（DPPH())自由基清除活性、氧自由基吸收能力（ORAC）和总酚含量来评价野生稻的抗氧化特性。野生稻的抗氧化活性被发现比对照白米高 30 倍。生的、混合的和加工的样品之间的抗氧化活性存在显著差异（p < 0.05）。对于生的样品，DPPH()自由基清除活性和 ORAC 值分别为 611 至 917 微摩尔 Trolox 当量（TE）/100g 和 4069 至 6064 微摩尔 TE/100g。对于混合和加工的野生稻，DPPH(*)自由基清除活性分别为 373 和 441 微摩尔 TE/100g。相应的 ORAC 值分别为 2284 和 2557 微摩尔 TE/100g。生野生稻的总酚含量（TPC）为 2472 至 4072 毫克阿魏酸当量（FAE）/kg，高于混合样品（1460 毫克 FAE/kg）和加工样品（2076 毫克 FAE/kg）。TPC 与野生稻的总抗氧化活性高度相关（r = 0.92）。串联质谱技术揭示了在野生稻中鉴定出的抗氧化剂是黄酮糖苷（二葡萄糖芹菜素、葡萄糖阿拉伯糖苷芹菜素和二阿拉伯糖苷芹菜素）在 2 区和 3 区和黄烷-3-醇（儿茶素、表儿茶素和低聚原花青素）在 4 区和 5 区。
