尿素包合法富集纯化杜仲籽油α-亚麻酸的工艺优化

采用二次正交旋转组合设计,对尿素包合法富集纯化杜仲籽油中α-亚麻酸的工艺进行了优化研究.在单因素实验的基础上,以α-亚麻酸纯度为考察指标,考察了尿素与脂肪酸质量比、95％乙醇与脂肪酸质量比、包合温度、包合时间等四个实验因素对α-亚麻酸富集效果的影响,建立了二次多元回归方程预测模型.实验结果表明α-亚麻酸最佳富集工艺条件为:尿素与脂肪酸质量比为3∶1,95％乙醇与脂肪酸质量比为9∶1,包合温度为-9.0℃,包合时间为17.0h.在此最佳富集条件下,α-亚麻酸纯度可提高至82.63％.尿素包合法是富集纯化杜仲籽油α-亚麻酸的有效方法.     

杜仲籽油亚临界萃取工艺优化及脂肪酸组成分析

以杜仲籽为原料,4号溶剂为提取剂,采用单因素试验和正交试验对杜仲籽油的亚临界萃取工艺进行优化。重点探讨料液比、萃取温度、萃取时间、萃取压力、萃取次数对杜仲籽粕残油率的影响,并采用GC分析杜仲籽油的脂肪酸组成。结果表明:杜仲籽油的最佳亚临界萃取工艺条件为料液比1∶5、萃取温度35℃、萃取时间1.0 h、萃取压力0.5 MPa、萃取次数3次,该条件下杜仲籽粕残油率为0.85%;杜仲籽油的主要脂肪酸为亚麻酸、亚油酸、油酸、棕榈酸和硬脂酸,其不饱和脂肪酸含量在90%以上。     

花椒籽仁油多不饱和脂肪酸乙酯的制备及氧化稳定性研究

为提高花椒籽仁油的降脂活性和氧化稳定性,将其制备成富含α-亚麻酸乙酯的多不饱和脂肪酸乙酯(PUFAEE)。以自制的花椒籽仁油为原料,以α-亚麻酸乙酯产率为检测指标,优化碱催化法制备混合脂肪酸乙酯的工艺,利用硝酸银络合法分离纯化出PUFAEE,测定其氧化诱导时间(OIP)。结果表明,在乙醇钠用量为0.5%(wt%)、醇油体积比为6∶1、反应温度为60℃、反应时间为60min的条件下制备混合脂肪酸乙酯,α-亚麻酸乙酯产率达94.69%;分离纯化的PUFAEE富含α-亚麻酸乙酯(76.9%),氧化稳定性好,其OIP为(5.39±0.07)h,远远高于花椒籽仁油的OIP(0.62±0.05)h;芝麻酚可作为花椒籽仁油及其PUFAEE的抗氧化剂,其强化作用呈现一定的量效关系。     

尿素包合法分离花椒籽油中α-亚麻酸工艺研究

采用尿素包合法从花椒籽油中提取α-亚麻酸,使其中饱和脂肪酸与不饱和脂肪酸分离,从而提高不饱和脂肪酸的含量.通过正交试验考察了包合反应中混合脂肪酸(FFA)、尿素、95％乙醇的用量、包合温度、包合时间等因素对产物中α-亚麻酸含量的影响,确定了最佳的优化条件:混合脂肪酸(FFA)∶尿素∶乙醇=1∶3∶9,包合温度0℃,包合时间16h.通过气相色谱-质谱联用仪(GC-MS)对包合后脂肪酸成份进行了分析,发现包合后共检测出3种不饱和脂肪酸,使α-亚麻酸的相对含量由4.12％提高到15.74％.     

猕猴桃籽油混合脂肪酸制备方法的比较研究

本文研究了酸解法、碱解法和碱解改良法制备混合脂肪酸的方法,通过比较认为以碱解改良法最为理想,皂化温度50℃,皂化时间50min时,混合脂肪酸得率为88.14%,碘值为187.3gI2/100g.     

β-环糊精包合法纯化混合脂肪酸中α-亚麻酸的工艺条件优化

以亚麻籽油为原料,对提取α-亚麻酸的方法进行了研究。采用β-环糊精包合法从亚麻籽油中提取α-亚麻酸,以α-亚麻酸含量为指标。采用单因素实验和响应曲面法分析建立二次回归模型,对包合温度、包合时间和β-环糊精与(混合脂肪酸+无水乙醇)用量之比三个影响因素进行优化组合,确定了β-环糊精包合法提取α-亚麻酸的最佳工艺条件,即:包合温度为60℃,包合时间为2.2h,β-环糊精与(混合脂肪酸+无水乙醇)比为7.14∶1。在此条件下,α-亚麻酸的含量为71.45%。采用紫外光谱检测将样品与标准品进行对照,确定样品为α-亚麻酸。     

苏子油的精炼及油中α—亚麻酸的纯化研究

苏子油中富含人体所需的α－亚麻酸，具有极大的保健价值。采用碱炼法精炼苏子粗油、，得苏子精油。其最佳条件为：过碱量５－１０％，皂化温度：３０－４０℃，精油后皂化水解后，采用脲我合法纯化α－亚麻酸，可将α－亚麻酸的含量由粗油中的５７．０５％提高到８４．２４％。     

猕猴桃籽油混合脂肪酸制备方法的比较研究

本文研究了酸解法、碱解法和碱解改良法制备混合脂肪酸的方法,通过比较认为以碱解改良法最为理想,皂化温度50℃,皂化时间50min时,混合脂肪酸得率为88.14%,碘值为187.3gI2/100g。     

奇亚籽油脂肪酸乙酯的制备工艺研究

以奇亚籽油为原料,采用碱催化法制备奇亚籽油脂肪酸乙酯。对比甲醇钠、乙醇钠和氢氧化钠的催化效果,并通过单因素实验和正交实验优化奇亚籽油脂肪酸乙酯制备的工艺参数。结果表明：采用氢氧化钠为催化剂,乙酯含量和得率均最高;当酯交换温度为80 ℃、酯交换时间为1.5 h、醇油摩尔比为9∶ 1、氢氧化钠用量为油质量的0.6%时,奇亚籽油脂肪酸乙酯含量可达到89.01%。     

大鲵油不饱和脂肪酸的富集研究

采用常压皂化水解法制备大鲵油混合脂肪酸,采用低温结晶法对大鲵油不饱和脂肪酸进行富集研究。得到大鲵油混合脂肪酸制备最佳工艺条件为:皂化比例1∶6,皂化温度65℃,皂化时间2.5 h。在最佳条件下,混合脂肪酸酸值(KOH)为236.76 mg/g。低温结晶法富集大鲵油不饱和脂肪酸的最佳工艺条件为:溶剂比例1∶6,结晶温度-45℃,结晶时间5 h。在最佳条件下,脂肪酸的碘值(I)为188.67 g/100 g,回收率为70.14%,不饱和脂肪酸的含量提高了14.20个百分点,多不饱和脂肪酸的含量提高了10.29个百分点。     

Biological modification of the fatty acid group in an emulsan by supplementing fatty acids under conditions inhibiting fatty acid biosynthesis

When the concentration of the antibiotic cerulenin was increased up to 3.0 mg/l in medium containing ethanol as a carbon source, the specific growth rate of Acinetobacter calcoaceticus and the fatty acid content of the emulsan decreased from 0.179 h(-1) and 13.9% to 0.015 h(-1) and 3.4%, respectively. The emulsifying activity in medium containing cerulenin decreased with increasing cerulenin concentration. In the culture containing 3.0 mg/l cerulenin, fatty acid biosynthesis was inhibited. Various fatty acids were added to this inhibitory culture as a second carbon source to modify the fatty acid group in the emulsan. When an odd-numbered fatty acid was added, the resulting emulsan was found to have other odd-numbered fatty acids that were not present originally. Among the emulsan produced from even-numbered fatty acids, the emulsan produced from myristic acid (C14) contained the greatest amount of the same-numbered fatty acids. When the amount of supplemental myristic acid was increased, the myristic acid content in the emulsan increased, but its emulsifying activity decreased.     

Egg yolk fatty acid profile in relation to dietary fatty acid concentrations

BACKGROUND: The health benefits of n‐3 fatty acids have led to much research on manipulating the fatty acid composition of animal‐derived foods. In this study, two experiments were conducted to investigate the interaction of dietary fatty acids on egg yolk fatty acid concentrations. In experiment I, 32 dietary treatments with three replicates of three birds each were fed for 35 days. Diets were prepared by mixing one type of fish oil with four vegetable oils in different proportions. In experiment II, three different types and two levels of fish oil in combination with two vegetable oils were tested under the same conditions as in experiment I. RESULTS: In experiment I the results showed that the egg yolk saturated (SFA) and monounsaturated (MUFA) fatty acid concentration was determined by the dietary SFA, MUFA and 18:2n‐6 content. The egg 18:2n‐6 concentration was mainly explained by the dietary inclusion of 18:2n‐6 and negatively by the dietary MUFA content. The egg C18:3n‐3, C20:5n‐3 and C22:6n‐3 concentration is almost exclusively determined by their direct supply from the diet. The egg 20:4n‐6 concentration was inversely proportional to the long‐chain n‐3 polyunsaturated fatty acid content of the diet. The results of experiment II showed that the egg yolk C20:5n‐3 and C22:6n‐3 concentration was determined by both the level of dietary fish oil (1 or 2%) and the C20:5n‐3/C22:6n‐3 ratio in the fish oil. CONCLUSION: The results of this study demonstrated that the direct dietary supply of fatty acids is the most important factor determining the egg yolk fatty acid composition, in particular for the n‐3 fatty acids. The interaction effect from other dietary fatty acids was in general small. Copyright © 2011 Society of Chemical Industry     

Carcass fatty acid mapping

We hypothesized that subcutaneous (s.c.) adipose tissue would differ in monounsaturated (MUFA) and saturated fatty acid (SFA) composition among different depots throughout a beef carcass. To test this, 50 carcasses from a variety of breed types and backgrounds were sampled. External fat samples were collected from eight different carcass locations: round, sirloin, loin, rib, chuck, brisket, plate and flank. The brisket was significantly lower (P = 0.001) in palmitic (16:0) and stearic (18:0) acid than the other seven sampling sites. The brisket contained the highest concentration of MUFA (P = 0.001) and the lowest concentration of trans-vaccenic acid (P = 0.002) and SFA (P  0.002). There was a high, negative correlation between palmitoleic and stearic acid (R² = 0.76). The flank had the highest slip point (39 °C; a measure of melting point), whereas the brisket had the lowest slip point (25 °C) (P  0.001). We conclude that substantial differences exist in fatty acid composition across fat depots, which may be useful in formulating value-added processed beef products.     

选择食用油调味品时应注意脂肪酸比例

通过分析构成脂肪的3种脂肪酸的性质及对人体的影响，提出了有利于人体健康的选择食用油的方法。     

蔗糖脂肪酸酯的合成工艺研究

以废弃油脂生产的脂肪酸甲酯和蔗糖为原料,无溶剂法合成蔗糖酯.通过单因素试验和正交试验确定最佳工艺条件为:脂肪酸甲酯与蔗糖摩尔比2.5∶1,催化剂无水碳酸钾用量为原料总质量的3％,乳化剂脂肪酸钾用量为原料总质量的15％,反应温度135 ℃,反应时间4h.在最佳工艺条件下,蔗糖酯产率为78.9％.所合成的蔗糖酯的HLB值为11,红外表征确证了蔗糖酯的合成.     

反式脂肪酸危害与控制

通过对食品中反式脂肪酸含量强制标示,向广大消费者指出反式脂肪酸对人体健康危害；同时对油脂加工业而言,这也意味着一场旨在减少食品中反式脂肪酸变革开始。     

人初乳脂肪酸组成及sn-2位脂肪酸分布的研究

选择广州市健康产妇20例,用超声法快速萃取乳中脂肪,采用DM-FFAP毛细管柱气相色谱对人初乳脂中总脂肪酸组成及sn-2位脂肪酸进行了测定,并采用SPSS13.0软件对测定数据进行统计分析。结果表明:总脂肪酸组成中饱和脂肪酸(主要为棕榈酸)含量低,为36.47%,不饱和脂肪酸含量高(主要为油酸和亚油酸),为63.9%;sn-2位脂肪酸组成中饱和脂肪酸含量为61.48%,不饱和脂肪酸含量为37.95%;棕榈酸多分布在sn-2位(72.08%),油酸和亚油酸多分布在sn-1,3位。初乳中脂肪酸的组成和分布具有独特的特点,对婴儿生长发育具有非常重要意义,本文对开发人乳脂替代品具有理论指导意义。     

谷氨酸棒杆菌脂肪酸合成酶fasA基因的异源表达对脂肪酸合成的影响

旨在为脂肪酸高产菌株的筛选和构建奠定理论基础，研究谷氨酸棒杆菌脂肪酸合成酶A(FasA)对大肠杆菌脂肪酸合成的影响，利用生物信息学软件预测分析了FasA的性质并构建过表达载体pXMJ19-fasA,转化至大肠杆菌进行表达，对表达诱导剂异丙基-β-D-硫代吡喃半乳糖苷(IPTG)浓度进行考察，并测定了异源表达后的脂肪酸组成。结果表明，重组菌株在IPTG浓度为1 mmol/L下诱导20 h,棕榈油酸和油酸产量分别达到1.735、2.325 mg/g,与对照菌株相比分别提高了53.95%和59.68%。研究结果说明FasA对大肠杆菌合成棕榈油酸和油酸有促进作用。     

沙棘油脂肪酸、sn-2位脂肪酸及甘三酯的测定与分析

采用超临界CO_2萃取得到沙棘籽油和沙棘全果油,并采用气相色谱和超高效液相色谱-飞行时间质谱对其脂肪酸、sn-2位脂肪酸及甘三酯组成进行测定与分析。结果表明:沙棘籽油中亚油酸、亚麻酸和油酸的含量较多,分别为38.71%、25.66%和20.68%,这3种脂肪酸也是其主要的sn-2位脂肪酸,含量分别为46.46%、25.49%和23.02%;LOL(13.65%)、OLO(12.06%)和LLn O(11.23%)是沙棘籽油的主要甘三酯类型;沙棘全果油中棕榈油酸(36.86%)、棕榈酸(27.27%)和油酸(18.00%)的含量较高,主要的sn-2位脂肪酸为棕榈油酸(45.57%)和油酸(32.06%);沙棘全果油的主要甘三酯为POPo(14.38%)、PoOPo(13.77%)和OPO(12.06%)。     

Acetyl CoA carboxylase shares control of fatty acid synthesis with fatty acid synthase in bovine mammary homogenate

The objectives of this research were to determine the flux control coefficients for acetyl CoA carboxylase and fatty acid synthase using an in vitro preparation of bovine mammary homogenate. For an enzyme to be considered rate limiting with the use of metabolic control analysis, its control coefficient would be equal to unity. The hypothesis for this experiment was that the control coefficient for acetyl CoA carboxylase was not equal to unity, and that this enzyme was not, therefore, the rate-limiting step. Mammary tissue was isolated from lactating Holstein cows at slaughter and frozen in liquid nitrogen. Tissue was ground, homogenized, and centrifuged to obtain a postmitochondrial supernatant for use in in vitro incubations containing labeled acetate. Specific inhibitors for acetyl CoA carboxylase and fatty acid synthase were used to fractionally inhibit de novo synthesis for the calculation of flux control coefficients. The composition of fatty acids synthesized in the absence of enzyme inhibitors was similar to the composition of fatty acids in the presence of inhibitors. Calculations following avidin inhibition of acetyl CoA carboxylase determined the flux control coefficient was 0.63 ± 0.15, which means that 63% of the control of fatty acid synthesis is exerted by acetyl CoA carboxylase. The remaining control (37%) was from fatty acid synthase, which indicates a significant degree of control over the flux of acetate in de novo synthesis resides with this enzyme. The rate-limiting status ascribed to acetyl CoA carboxylase was not supported, because the flux control coefficient was less than unity. Metabolic control analysis, through its use of pathway product measurements, allows for potential interactions in the pathway such as feedback inhibition contribution to the flux control coefficients, which would not otherwise be considered in studies measuring enzyme kinetics with purified enzymes.