低压离子色谱柱后偶合化学发光测定蔬菜中碘离子

以NaNO3作洗脱液,碘离子经低压离子色谱柱分离与KIO4反应后,再与鲁米诺发生化学发光。经试验测定碘离子浓度在8.0×10-5~5.0×10-8g/mL范围内与发光强度呈良好的线性关系;检出限为8.0×10-9g/mL(3σ);相对标准偏差为0.8%。     

Extraction of rice brain oil using supercritical carbon dioxide and propane

Extraction of rice bran lipids was performed using supercritical carbon dioxide (SC−CO₂) and liquid propane. To provide a basis for extraction efficiency, accelerated solvent extraction with hexane was performed at 100°C and 10.34 MPa. Extraction pressure was varied for propane and SC−CO₂ extractions. Also, the role of temperature in SC−CO₂ extraction efficiency was investigated at 45,65, and 85°C. For the SC−CO₂ experiments, extraction efficiencies were proportional to pressure and inversely proportional to temperature, and the maximal yield of oil achieved using SC−CO₂ was 0.222±0.013 kg of oil extracted per kg of rice bran for conditions of 45°C and 35 MPa. The maximal yield achieved with propane was 0.224±0.016 kg of oil per kg of rice bran at 0.76 MPa and ambient temperature. The maximum extraction efficiencies of both SC−CO₂ and propane were found to be significantly different from the hexane extraction baseline yield, which was 0.261±0.005 kg oil extracted per kg of rice bran. A simulated economic analysis was performed on the possibility of using SC−CO₂ and propane extraction technologies to remove oil from rice bran generated in Mississippi. Although the economic analysis was based on the maximal extraction efficiency for each technology, neither process resulted in a positive rate of return on investment.     

马桑皮植鞣剂与铝盐结合鞣制性能及机理

以提取于马桑皮的植物鞣剂为原料，与铝盐进行绵羊酸皮结合鞣制，优化鞣制工艺并建立基于马桑皮鞣剂的植铝结合鞣制方法，对鞣制后皮革性能及鞣制机理进行研究。结果表明，当马桑皮鞣剂用量为酸皮质量的15%、Al3(SO4)2•18H2O用量为酸皮质量的20%、渗透pH为4.0、结合pH为4.5的条件下，皮革收缩温度可达110.5 ℃。皮革表观性能良好，增厚率为82.2%，抗张强度为10.0 MPa，撕裂强度为52.5 N/mm，断裂伸长率为76.8%，优于橡椀植物鞣剂结合鞣制的皮革。鞣制后皮革胶原纤维变粗，形成紧密的网状结构。马桑皮植物鞣剂能充分渗透至皮革胶原纤维中，并与其产生氢键交联。在结合鞣制时，铝盐与皮革胶原纤维中结合的单宁类成分产生络合，使交联作用增强，从而显著提高成革的热稳定性能和机械性能。     

基于气相色谱方法的植物油脂肪酸分析探究

从材料、试剂、仪器、方法等方面入手,介绍了植物油脂肪酸分析实验用到的材料与方法;其次,从定性和定量分析、色谱柱的选择、甲酯化体系的选择、反应温度影响、精密度和稳定性实验、实际样品测定及植物油脂肪酸组成特点、聚类分析七个方面入手,研究了植物油脂肪酸分析实验的结果与分析;最后,总结了植物油脂肪酸分析实验的结论。希望通过这次研究,为实验人员加深对基于气相色谱方法的植物油脂肪酸分析有更深刻的认识和了解。     

草本植物提取物在果蔬贮藏中的研究进展

我国果蔬保鲜长期依赖化学保鲜剂,但随着使用次数的增加,抗药性及对人类健康危害的问题日益突出.草本植物的提取物绿色、环保,成为近些年保鲜剂开发的热点.论述了保鲜剂开发中的植物资源、提取方法、杀菌原理及其应用进展,指出了开发过程中将面临的问题及其发展前景.     

菜籽油酯交换制备植物绝缘油及电气性能研究

菜籽油与甲醇在氢氧化钠的催化下通过酯交换反应制得菜籽绝缘油。结果表明,最佳酯交换工艺条件为：醇油摩尔比为9：1,催化剂用量为油质量的0．4％,反应温度为60℃,反应时间为75min,转化率为94．89％;最佳精炼工艺条件为：活性白土吸附脱色的用量为5％,搅拌时间为25min,搅拌温度为80℃,碱性氧化铝吸附降酸值温度为60℃,时间为60min;所得菜籽绝缘油闪点为160℃,酸值为0．025mgKOH／g,工频击穿电压达到55．5kV,90℃介质损耗为0．010,90℃体积电阻率为21．8GΩ·m,相对介电常数ε,为2．839。     

Lipophilicity of Flavonoids Estimated by Reversed-Phase High Performance Thin-Layer Chromatography: Chemically Bonded Plates vs. Impregnated Plates with Oils,Animal, and Human Fats

Silica gel plates impregnated with a variety of oils (olive oil, sunflower oil, corn oil, trioctylamine, and paraffin oil) and fats (margarine, butter, cod liver fat, pig fat, sheep fat, pullet fat, and human fat) were evaluated and compared with the commercially available reversed-phases TLC plates (RP-18, RP-18 W, and CN). A representative series of flavonoids is employed to evaluate the suitability of oils and fats as reversed-phases for TLC and to provide different lipophilicity indices: R_M0, scores corresponding to first principal component of R_F and/or R_M, arithmetic mean of R_F and R_M values obtained with solvent mixture containing various concentrations of methanol in water. The retention results were excellent (r > 0.96) and allowed for accurate estimation of lipophilicity of selected flavonoids and to ranking the lipophilicity of oils and fats when comparing with chemically bonded phases. The human fat-impregnated plates provided lipophilicity values closely associated with those obtained for margarine and butter. Moreover, the human fat lipophilic character seems to be placed between pullet and cod fats. Concerning the lipophilicity scale of vegetable oils, it is worth noting that the corn oil presents the highest lipophilicity, closely followed by the sunflower and olive oils.     

Evaluation of vitamin E by HPLC in a variety of olive-based foodstuffs

A survey of vitamin E levels in a wide variety of olive-based foodstuffs was conducted. Vitamin E was determined by normal-phase HPLC. The only form of vitamin E found in all commercial presentations of table olives was α-tocopherol, with an average content of 3.1 mg/100 g edible portion. A very low content (<0.4 mg/100 g edible portion) of γ-tocopherol was found in most of the samples analyzed. The main sources of variation of vitamin E were olive cultivars and commercial presentations. Processing type (Spanish style green olives, directly brined olives, ripe olives) had a limited influence. Irrespective of the elaboration style, the Gordal cultivar was the poorest with respect to the vitamin E content. On the other hand, all commercial presentations based on the Hojiblanca cultivar had high contents of vitamin E. The results of this study may be used by the industry for requirements of nutritional labeling or by nutritionists to estimate vitamin E intakes in diets that include table olives.     

生物油制备、性质与应用的研究进展

介绍了国内外生物油的发展现状。根据生物油制备原料不同,将其分为植物油、热裂解油和生物柴油等。概括了生物油制备的方法和原理,分析3种生物油的物理化学性质。综述了生物油的主要应用方式,包括食品加工、化工应用和燃烧应用等。最后总结了生物油领域存在的主要问题,并对生物油应用方面的发展方向进行了展望。