不同产地米糠油理化特性与组成分析研究

以不同产地的米糠原油为原料,分析测定了其相对密度、折光指数、皂化值等理化指标;采用气相色谱法分析了米糠油的脂肪酸组成.结果表明:米糠油主要由7种脂肪酸组成,全样脂肪酸组成中油酸(C18∶1/O)含量最高,相对含量为39.78%~42.18%,其次是亚油酸(C18:2/L),相对含量33.25%~37.16%,二者含量之和接近80%;米糠油的甘三酯分子结构组成中OOL(17.24%~19.43%),LOL(16.59%~17.79%),POL(12.90%~16.43%)相对含量较高,其他甘三酯含量较低;高效液相色谱法测定米糠油中维生素E含量为69.31~127.76 mg/100 g,不同产地有明显差异;采用分光光度法测定米糠油中总甾醇和谷维素含量,辽宁省米糠油甾醇含量最高,为3.38%,黑龙江米糠油谷维素含量最高,可达1.98%.     

Beneficial effect of the unsaponifiable matter from rice bran on oxidative stress in vitro compared with α‐tocopherol

Unsaponifiable matter (UM) was prepared from rice bran using n‐hexane extraction followed by removal of its fatty acid methyl ester with supercritical CO₂ under heat‐stable conditions. The UM was made up of 1% of vitamin E isomers, 28% of γ‐oryzanol and 71% of uncharacterized compounds. The aim of this study was to determine the antioxidant activities of the UM, using α‐tocopherol (α‐T) as a positive control, by measuring the Fe³⁺‐reducing antioxidant power (FRAP), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) free‐radical‐scavenging property and lipid peroxidation in rat liver microsomes. In addition, the effects of the UM on the tert‐butyl hydroperoxide (t‐BOOH)‐induced cytotoxicity in cultured rat hepatocytes were also investigated. In FRAP assay and DPPH^? free‐radical‐scavenging assay, the results were expressed g^?1α‐T or g^?1 UM. The amount of UM used in lipid peroxidation assay and cytotoxicity assay was the amount required to have equal amounts of total vitamin E isomers in the sample and the control α‐T. The UM, as well as α‐T, exhibited significant antioxidant activities in FRAP, radical‐scavenging and membrane‐lipid oxidation. The FRAP value for total vitamin E isomers in the UM (TVEIUM) was 9.1 times higher than that for α‐T. In terms of their capacities to perform radical‐scavenging and lipid peroxidation, both TVEIUM and α‐T showed similar antioxidant activities. In experiments using cultured rat hepatocytes, the t‐BOOH‐induced lactate dehydrogenase release was significantly inhibited by the addition of 63.5 and 160 µg ml^?1 of TVEIUM treatments (84 and 89%, respectively), and that of 63.5 and 160 µg ml^?1 of α‐T treatment (88 and 93%, respectively). The antioxidant function against oxidative stress of the UM prepared from rice bran may extend its use to being a potential dietary supplement. Copyright © 2004 Society of Chemical Industry     

高效液相色谱法测定米糠油中谷维素

建立固相萃取柱—液相色谱法测定米糠油中谷维素六种谷维素组分及总量的检测方法。采用二醇基固相萃取小柱提取净化样品,以谷维素混合标准品(γ-Oryzanol)进行定量,色谱柱为Agilent ZORBAX Eclipse Plus C18(250 mm×4.6 mm,5μm),流动相为含1%乙酸的乙腈∶异丙醇=95∶5,紫外检测器检测(波长321 nm)。六种谷维素组分及总量的平均回收率分别为95.6%~105.7%、97.8%~100.2%,精密度分别为0.1%~4.6%、0.7%~3.4%。该方法可用来测定米糠油中谷维素组分及总量,为深入研究谷维素提供技术支持。     

分子蒸馏单甘酯对谷维素-谷甾醇凝胶油结构和性质的影响

以精炼葵花籽油为基料油,添加分子蒸馏单甘酯与谷维素-谷甾醇制备复合凝胶油,探讨凝胶剂分子间比例对凝胶油结构和性质的影响,以分析单甘酯在复合凝胶油形成过程中的作用。结果表明：在复合凝胶油中单甘酯会与谷甾醇存在着范德华力等弱的非氢键作用力,使得单甘酯和谷甾醇在临界凝胶浓度下,协同形成复合凝胶油。单甘酯的添加对复合凝胶油热力学性质和流变学性质等宏观特性均产生较大影响,添加单甘酯后复合凝胶油微观结构和红外光谱产生了显著变化,随着单甘酯含量的增加,氢键作用逐渐减小直至消失,而微观结构由纤维网状到球状结晶最后为针状结晶;结果还表明添加单甘酯后凝胶油氧化更慢,利于长期贮藏。     

米糠混合油碱炼脱酸工艺效果的研究

研究了米糠混合油碱炼脱酸工艺条件对提高碱炼得率和降低谷维素、甾醇等营养成分损失率的影响。结果表明:高酸值米糠毛油采用混合油碱炼脱酸比毛油碱炼脱酸在提高碱炼得率、降低谷维素和甾醇损失方面有显著优势;最佳的米糠混合油碱炼脱酸工艺条件为碱炼温度55℃,总加碱量为理论加碱量加0.3%超量碱(占油质量),混合油浓度40%,碱液质量分数11.06%;在最佳条件下,米糠混合油碱炼得率71.62%,谷维素损失率63.22%,甾醇损失率43.76%,较米糠毛油碱炼脱酸的碱炼得率提高16.48个百分点,谷维素损失率降低30.56个百分点,甾醇损失率降低21.41个百分点。