月苋草油制备共轭亚油酸的研究

GC—MS分析月苋草油中脂肪酸的组成,其亚油酸含量很高。探讨制备和富集提纯亚油酸反应条件,研究在高压条件下金属催化剂对亚油酸共轭化的影响。     

碱法异构化亚油酸甲酯制备共轭亚油酸

该文探索在乙二醇溶剂中以氢氧化钠碱法异构化亚油酸甲酯制备共轭亚油酸的方法,适宜的异构化条件为m(氢氧化钠)∶m(亚油酸甲酯)∶m(乙二醇)=1∶5∶8.4,170℃反应4 h,亚油酸甲酯转化率和共轭亚油酸产率分别为92.4%和89.3%。该法比目前常用的亚油酸原料法的优越之处体现在:以氢氧化钠取代常用碱氢氧化钾,降低成本;以亚油酸甲酯取代亚油酸为原料,避免了原料本身大量消耗碱;反应初期避免原料大量皂化,减小了体系的传质阻力,因而减少了溶剂乙二醇消耗量。     

乙二醇单丁醚为溶剂制备共轭亚油酸的研究

以乙二醇单丁醚作为溶剂,KOH作催化剂,碱催化异构化法用豆油制备共轭亚油酸.通过正交设计,紫外光谱分析法考察了4种因素对亚油酸转化率的影响,并得出制备高亚油酸油脂合适的工艺条件:反应温度135℃,反应时间3 h,强碱催化剂与原料质量比为0.4:1,原料与溶剂质量比为2:3.在此条件下,亚油酸的平均转化率超过96%.结果表明,该溶剂能使反应在均相反应体系中较为温和的温度条件下较短的时间内完成.     

乙二醇单丁醚为溶剂制备共轭亚油酸的研究

以乙二醇单丁醚作为溶剂,KOH作催化剂,碱催化异构化法用豆油制备共轭亚油酸。通过正交设计,紫外光谱分析考察了4种因素对亚油酸转化率的影响,并得出制备高亚油酸油脂合适的工艺条件:反应温度135℃,反应时间3 h,强碱催化剂与原料质量比为0.4∶1,原料与溶剂质量比为2∶3。在此条件下,亚油酸的平均转化率达到96.8%。结果表明,该溶剂能使反应在均相体系中较为温和的温度条件下较短的时间内完成。     

光皮树油催化异构化反应产物结构分析

以光皮树油为原料,对不饱和脂肪酸于碘、三氯化钌及碱3种催化剂催化异构化反应进行了研究,探讨了孤立双键与共轭双键转化机理,通过UV、GC、GC-IR及GC-MS法,分析了共轭酸的主要成分、共轭结构及构型.结果表明,异构化催化剂对光皮树油共轭酸构型起决定性作用,氢氧化钠催化异构化共轭酸构型以顺-反式为主,而三氯化钌及碘催化异构化共轭酸构型则同时生成顺-反式及反-反式,两种构型比例为1:1.     

磺草酮与莠去津混用对稗草及反枝苋防效研究

在温室栽培条件下,采用Gowing法评价磺草酮与莠去津混用的联合作用类型。结果表明,二者混用后对稗草和反枝苋的作用效果均明显提高;混合剂对稗草表现出明显的增效作用,在磺草酮400g/hm2,莠去津800、900g/hm2时对稗草和反枝苋的增效作用最为明显,其鲜重抑制率(E-E0)分别为9.1%和9.5%;混合剂对反枝苋作用效果表现为相加作用。     

完全异构化工艺技术的研究

简单介绍了完全异构化工艺的2种流程,并对该工艺的以下几方面进行了分析异构化油的特点、常用异构化催化剂的特点、常用吸附剂的特点、不同原料的进料方案和工艺操作条件等.采用完全异构化工艺可以生产出低硫且不含烯烃、芳烃和苯的异构化油,是一种优良的汽油调和组分.     

乙羧氟草醚与精喹禾灵混用对稗草、反枝苋防效研究

在温室栽培条件下,采用Gowing法评价乙羧氟草醚与精喹禾灵混用的联合作用类型,结果表明。二者混用后对稗草和反枝苋的两种杂草均具有良好的防治效果;混剂对两种杂草作用效果均表现为相加作用。     

红花油制取共轭亚油酸的研究

以新疆克拉玛依厂的红花油为原料,以丙三醇为溶剂,在KOH的碱性催化作用下,将红花油先转化成亚油酸钾;再利用异构化反应制得浅黄色的共轭亚油酸产品。对产品进行了薄层层析法和紫外分光光度法定性分析,并定量分析了红花油异构化反应的程度。本研究对红花油的深加工将起到很好的推动作用。     

GC法同时测定火麻仁油中油酸、亚油酸和α-亚麻酸的含量

目的建立GC法同时测定火麻仁油中油酸、亚油酸和α-亚麻酸含量的方法。方法采用毛细管色谱柱CP-WAX 52CB(30 m×0.32 mm,0.50μm),柱温为205℃,FID检测器,检测器温度为300℃,进样口温度为250℃,分流比:10∶1,载气流速为1 mL·min~(-1),进样量为1μL。结果油酸甲酯、亚油酸甲酯和α-亚麻酸甲酯的质量浓度分别在7.60~152.00μg·mL~(-1)(r=0.9999)、8.00~160.20μg·mL~(-1)(r=0.9997)和9.70~194.00μg·mL~(-1)(r=0.9998)范围内线性关系良好,平均回收率分别为96.55%、99.68%、102.22%,RSD值分别为1.35%、2.79%、1.19%。结论该方法灵敏、准确、重复性好,可用于测定火麻仁油中油酸、亚油酸和α-亚麻酸的含量。     

Borage and evening primrose oil

The paper gives a short overview about the production and composition of borage (Borago officinalis) and evening primrose (Oenothera biennis) oil considering special aspects of the production as cold‐pressed oil. Both oils are characterized by a remarkable amount of γ‐linolenic acid, which has some nutritional advantages. The fatty acid composition of evening primrose oil is dominated by linoleic acid with about 72% and about 13% γ‐linolenic acid, while borage oil consists of twice the amount of γ‐linolenic acid and only 38% linoleic acid. The amount of saturated fatty acids is higher in borage oil. The tocopherol composition of both oils is dominated by γ‐tocopherol, with borage oil containing twice the amount compared to evening primrose oil.     

Supercritical carbon dioxide extraction of evening primrose oil

The oil extracted from the seeds ofOenothera biennis L. (evening primrose) is a major commercial source of gamma-linolenic acid, a fatty acid having potential therapeutic value in the treatment of several diseases. This fatty acid is prone to oxidation and thermal rearrangement; therefore, the conventional recovery of the oil via mechanical expression and hexane extraction must be carried out under very mild and controlled conditions. In this study, supercritical fluid extraction with carbon dioxide has been employed as an alternative method to recover evening primrose oil (EPO). Extractions were performed over the pressure range of 20–70 MPa and at temperatures from 40 to 60°C, with a CO₂ mass flow rate of 18 g/min. The experimental data permitted the determination of EPO solubility in supercritical CO₂ at the tested extraction conditions. Supercritical fluid Chromatographic analysis of fractions collected during the extraction showed a subtle shift in the triglyceride composition. Fatty acid methyl ester analysis on similar fractions indicated that the fatty acid content was invariant with respect to extraction time. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Triacylglycerols of evening primrose oenothera biennis seed oil

The triacylglycerol (TG) composition of evening primrose(Oenothera biennis) seed oil (EPO) was studied using a combination of silver nitrate thin layer chromatography (AgNO```3``-TLC), reverse phase high performance liquid chromatography (HPLC) and capillary gas liquid chromatography (GLC). The important TGs in EPO are LLL (24.4%), LLO (23.9%), LLP (11.5%), LOO (7.2%), LOP (6.8%), LLS (4.8%), γLnLp (3.7%), LOS (3.3%), γLnLS (2.0%), γLnLL (2.0%), LPP (1.9%), OOO (1.7%), LSP (1.3%) and γLnLO (1.0%).     

棕榈油碱催化制备生物柴油实验研究

用氢氧化钾作催化剂,考察了反应温度、催化剂用量、醇油摩尔比、反应时间对棕榈油和甲醇制备生物柴油产率的影响。结果表明,最佳反应条件为:反应温度40℃,催化剂用量0.6%,醇油摩尔比6∶1,反应时间2.0 h。此时,生物柴油产率可达97.82%。     

棕榈油碱催化制备生物柴油实验研究

用氢氧化钾作催化剂,考察了反应温度、催化剂用量、醇油摩尔比、反应时间对棕榈油和甲醇制备生物柴油产率的影响。结果表明,最佳反应条件为:反应温度40℃,催化剂用量0.6%,醇油摩尔比6∶1,反应时间2.0 h。此时,生物柴油产率可达97.82%。     

Gamma linolenic acid (GLA) content of encapsulated evening primrose oil products

The fatty acid composition of 16 brands of evening primrose oil (EPO) capsules was determined by capillary gas chromatography. Fourteen of these EPO brands contained γ-linolenic acid (GLA) levels between 7% and 10% (mean, 8.7; range, 1.9–10.5%) and there was generally good agreement between the level of GLA claimed by the manufacturer and the level determined by analysis. Low levels of the monoenes 22∶1 and 24∶1 found in some brands may indicate contamination of EPO with borage oil.     

Kinetics of supercritical carbon dioxide extraction of borage and evening primrose seed oil

In the present work, high‐pressure extraction of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) seed oil, containing the valuable γ‐linolenic acid (GLA), has been investigated. Extraction was performed with supercritical carbon dioxide on a semi‐continuous flow apparatus at pressures of 200 and 300 bar, and at temperatures of 40 and 60 °C. A constant flow rate of carbon dioxide in the range from 0.17 to 0.20 kg/h was maintained during extraction. The extraction yields obtained using dense CO₂ were similar to those obtained with conventional extraction using hexane as solvent. The composition of extracted crude oil was determined by GC analysis. The best results were obtained at 300 bar and 40 °C for both seed types extracted, where the quality of oil was highest with regard to GLA content. The evening primrose seed oil extracted with supercritical fluid extraction was particularly rich in unsaturated fatty acids: up to 89.7 wt‐% of total free fatty acids in the oil. The dynamic behavior of the extraction runs was analyzed using two mathematical models for describing the constant rate period and the subsequent falling rate period. Based on the experimental data, external mass transfer coefficients, diffusion coefficients and diffusivity in solid phase were estimated. Results showed good agreement between calculated and experimental data.     

Supercritical extraction of evening primrose oil: Experimental optimization via response surface methodology

Supercritical carbon dioxide (CO₂) effective extraction parameters (pressure, temperature, static extraction time, and dynamic extraction time) of oil recovery from evening primrose seeds were optimized via response surface methodology (RSM). The results of this study indicated that the linear terms of static and dynamic time and the quadratics of temperature and pressure, as well as the interactions of temperature and static time, pressure and temperature had a significant effect on the oil recovery. The optimum extraction conditions of 14.2 MPa, 47.3°C, 30 min (static extraction time) and 150 min (dynamic extraction time) were obtained. Applying the optimum conditions, a mean experimental recovery of 92.98% (triplicate experiment) was achieved, which is well compatible with the RSM‐predicted value (93.61%). The fatty acid composition of extracted evening primrose oil using supercritical CO₂ was compared with that obtained by Soxhlet method in which minor difference was observed. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Enrichment of γ-linolenic acid from evening primrose oil and borage oilvia lipase-catalyzed hydrolysis

Lipase-catalyzed selective partial hydrolysis of evening primrose (Oenothera biennis L.) seed oil and borage (Borago officinalis L.) seed oil led to an increase in the level of γ-linolenic acid (GLA; 18∶3n−6) in the unhydrolyzed acylglycerols. Thus, in evening primrose oil, the GLA level could be raised from 9.4% in the starting material to 46.5% in the unhydrolyzed acylglycerols by means of a lipase fromCandida cylindracea. Selective hydrolysis of borage oil with Pancreatin led to an increase in the GLA content from 20.4% in the oil to 33.5% in the unhydrolyzed acylglycerols. Partial hydrolysis of borage oil with lipase fromC. cylindracea raised the GLA content of the acylglycerols to 47.8%.     

γ-Linolenic acid concentrates from borage and evening primrose oil fatty acidsvia lipase-catalyzed esterification

γ-Linolenic acid (GLA, all-cis 6,9,12-octadecatrienoic acid) has been enriched from fatty acids of borage (Borago officinalis L.) seed oil to 93% from the initial concentration of 20% by lipase-catalyzed selective esterification of the fatty acids withn-butanol in the presence ofn-hexane as solvent. The immobilized fungal lipase preparation, Lipozyme, used as biocatalyst, preferentially esterified palmitic, stearic, oleic and linoleic acids and discriminated against GLA, which was thus concentrated in the unesterified fatty acids fraction. In the absence of hexane, concentrate containing about 70% GLA was obtained. When the reaction conditions, optimized for borage oil fatty acids, were applied to fatty acids of evening primrose (Oenothera biennis L.) oil, concentrates containing 75% GLA were obtained. From both oils, GLA concentrates were prepared efficiently in short reaction times (1–3 h) at 30–60°C. The process can be applied for the production of GLA concentrates for dietetic purposes.