Effect of temperature programming on the performance of urea inclusion compound-based free fatty acid fractionation

The effect of cooling rate on the degree of removal of saturated acyl groups from FFA derived from canola oil and the isolation of di- and polyunsaturated acyl groups from FFA derived from vegetable and fish oil, respectively, during urea inclusion compound (UIC)-based fractionation was investigated. Traditionally, slow cooling has been used (ca.−1°C min⁻¹). A more rapid cooling rate (−47°C min⁻¹) produced UIC crystals of similar morphology and thermodynamic properties, but of a size an order of magnitude smaller than the UIC formed during slow cooling. Fractionations used only renewable materials (urea, FFA, and 95% ethanol as solvent) and benign operating conditions (ambient pressure, 25–75°C, and neutral pH). When the recovery of FFA (in the solvent-rich phase) was relatively high (>60%), the selectivity of UIC-based fractionation toward the inclusion of saturated FFA and against polyunsaturated FFA was not affected by the cooling rate. In contrast, when the FFA recovery was low, representing cases in which an increase of the PUFA purity is a more important economic goal, a slower cooling rate resulted in a significantly greater discrimination against PUFA groups, hence to a FFA product with a measurably greater purity. This paper was presented at the 96th AOCS Anual Meeting and Expo, Salt Lake City, Utah, on May 4, 2005.     

甲鱼油中多不饱和脂肪酸的提取与纯化研究

本文研究了甲鱼油中多不饱和脂肪酸的提取与纯化。采用乙酯化法提取甲鱼油中的多不饱和脂肪酸,通过正交实验确定了最佳提取条件:乙醇/甲鱼油比0.73:1,NaOH用量3%(油重),反应温度65℃,反应时间2h;采用尿素包合法纯化多不饱和脂肪酸,考察尿素用量、搅拌时间、包合次数对尿素包合率的影响,通过正交实验确定最佳纯化条件:尿素/乙醇饱和溶液:脂肪酸乙酯=15:1,搅拌时间3h,包合次数1次。实验结果表明,应用乙酯化法与尿素包合法可从甲鱼油中制得高纯度的多不饱和脂肪酸。     

多不饱和脂肪酸萃取中超临界技术的应用进展

详细介绍了超临界技术在多不饱和脂肪酸萃取中的应用,对超临界技术的基础研究--相平衡研究以及超临界CO2萃取、超临界流体色谱法在多不饱和脂肪酸提纯中的工艺研究进行了综述,而且针对应用领域中的基础研究薄弱、萃取工艺难以工业化等问题,发表了自己的看法,提出了几点建议.     

Sage and rosemary essential oils versus BHT for the inhibition of lipid oxidative reactions in liver pâté

The antioxidant effect of two plant essential oils (sage and rosemary essential oils) and one synthetic antioxidant (BHT) on refrigerated stored liver pâté (4 °C/90 days) was evaluated. Pâtés with no added antioxidants were used as controls. Liver pâtés were analysed for the amount of polyunsaturated fatty acids (PUFA), thiobarbituric acid reactive substances (TBA-RS) numbers, and lipid-derived volatiles at days 0, 30, 60 and 90 of refrigerated storage. The amount of PUFA gradually decreased during refrigerated storage of porcine liver pâtés with this decrease being significantly greater (P<0.05) in control and BHT pâtés than in those with added essential oils. Consistently, the increase of TBA-RS numbers during refrigerated storage of liver pâtés was significantly higher in control pâtés than in the treated counterparts. At days 60 and 90, TBA-RS numbers in treated pâtés were significantly smaller (P<0.05) than in the control counterparts. Headspace solid-phase microextraction (HS-SPME) successfully isolated recognized indicators of lipid decomposition (i.e. hexanal, nonanal, hexan-1-ol, oct-1-en-3-ol, deca-(E,Z)-2,4-dienal) from liver pâtés whereas some other volatiles analysed are typical contributors to the overall off-flavour of oxidized liver (i.e. hept-(Z)-4-enal, non-(E)-2-enal, nona-(E,E)-2,4-dienal). The addition of antioxidants significantly (P<0.05) reduced the total amount of lipid-derived volatiles isolated from liver pâtés HS. Plant essential oils inhibited oxidative deterioration of liver pâtés to a higher extent than BHT did.     

Sesamin modulation of lipid class and fatty acid profile in early juvenile teleost, Lates calcarifer, fed different dietary oils

Sesamin, a major sesame seed lignan, has diverse biological functions including the modulation of molecular actions in lipid metabolic pathways and reducing cholesterol levels. Vertebrates have different capacities to biosynthesize long-chain PUFA from dietary precursors and sesamin can enhance the biosynthesis of ALA to EPA and DHA in marine teleost. Early juvenile barramundi, Lates calcarifer, were fed for two weeks on diets rich in ALA or SDA derived from linseed or Echium plantagineum, respectively. Both diets contained phytosterols and less cholesterol compared with a standard fish oil-based diet. The growth rates were reduced in the animals receiving sesamin regardless of the dietary oil. However, the relative levels of n-3 LC-PUFA in total lipid, but not the phospholipid, increased in the whole body by up to 25% in animals fed on sesamin with ALA or SDA. Sesamin reduced the relative levels of triacylglycerols and increased polar lipid, and did not affect the relative composition of phospholipid subclasses or sterols. Sesamin is a potent modulator for LC-PUFA biosynthesis in animals, but probably will have more effective impact at advanced ages. By modulating certain lipid metabolic pathways, sesamin has probably disrupted the body growth and development of organs and tissues in early juvenile barramundi.     

调和油生产与调和数学模型的建立

根据世界卫生组织与联合国粮农组织为发展中国家提供的ＳＦＡ∶ＭＵＦＡ∶ＰＵＦＡ＝１∶１∶１的建议,完成玉米调和油的调制过程,并建立调和数学模型。经使用,调和模型合理,可用于各种调和油的研制过程中     

分子蒸馏富集海狗油中多不饱和脂肪酸

海狗油中富含多不饱和脂肪酸,如二十碳五烯酸(EPA)、二十二碳五烯酸(DPA)、二十二碳六烯酸(DHA)等。用分子蒸馏法对海狗油中多不饱和脂肪酸进行富集,通过控制适宜的温度和压力等条件,得到较为满意的分离效果。当进料速率为80 mL/h,预热温度为80℃,刮膜器转速为250r/min,蒸馏温度为120℃,压力为15 Pa时,经过一级分子蒸馏,得到EPA、DPA和DHA的总含量为54.86%(质量分数)的海狗油产品,收率为92.7%,并用气相色谱法测定了产品的脂肪酸组成。     

Enzymatic modification of trilinolein: Incorporation of n-3 polyunsaturated fatty acids

Two immobilized lipases, IM60 fromMucor miehei and SP435 fromCandida antarctica, were used as biocatalysts for the modification of trilinolein with n-3 polyunsaturated fatty acids (PUFA), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), by using their ethyl esters as acyl donors (EEPA and EDHA, respectively). Transesterification (ester-ester interchange) reactions were carried out in organic solvent. The products were analyzed according to their equivalent carbon number and polarity by reverse-phase high-performance liquid chromatography, and the fatty acid profiles were determined by gas-liquid chromatography. Modified triacylglycerol products contained 1 or 2 molecules of n-3 PUFA. With EEPA as the acyl donor, the total EPA product yields with IM60 and SP435 as biocatalysts were 79.6 and 81.4%, respectively. However, with EDHA as the acyl donor and IM60 and SP435 as biocatalysts, the total DHA product yields were 70.5 and 79.7%, respectively. Effects of reaction parameters, such as type of solvent, enzyme load, time course, and molar ratio of substrates on the n-3 PUFA incorporation, were followed with SP435 as the biocatalyst. High yields were obtained, even in the absence of organic solvent. These lipids do hold promise for specialty nutrition and other therapeutic uses.     

Factors influencing proportion and composition of CLA in beef

Bovine meat is criticised for the bad nutritional image of its lipids and fatty acids. However, with dairy products, beef is the major source of conjugated linoleic acid (CLA) which could have several human health benefits. The present study compared, from data of five nutritional experiments on bovine animals performed by the laboratory, the impact of factors linked to the animals (breed, age, sex, type of muscle) and to feeding conditions (basal diet, lipid supplements) on the CLA proportion and composition in muscles. Among these factors, linseed supplementation was an efficient way to increase CLA proportion in beef (+22% to +36%) but was highly modulated by the nature of the basal diet, and by intrinsic factors (breed, age/sex, type of muscle) since these ones could modulate CLA proportion in beef from 24% to 47%. Moreover, these factors modified also the proportion of cis,trans-CLA, related to cis,cis- and trans,trans-isomers. Specific biological properties of these latter isomers should be determine to understand the consequences of intramuscular CLA isomer variations for the health of consumers.