皂化水解及尿素包合工艺对马齿苋油脂肪酸组成及抗氧化性影响

试验研究了皂化水解和尿素包合2个制备高纯度的马齿苋多不饱和脂肪酸的关键工艺对脂肪酸组成及抗氧化活性的影响。结果表明,皂化水解反应去除了马齿苋全草油中的山嵛酸,使多不饱和脂肪酸含量由64.23%提高到68.12%。经尿素包合法富集得到的高纯度多不饱和脂肪酸主要以亚油酸、亚麻酸为主,且占总量的91.35%。马齿苋全草油、混合脂肪酸、高纯度马齿苋多不饱和脂肪酸清除羟基自由基(·OH)的IC50值分别为(6.491±0.0455)、(3.088±0.0575)、(1.151±0.0515)mg/m L,DPPH·清除率的IC50值分别为(6.150±0.0109)、(4.138±0.0106)、(0.6889±0.0029)mg/m L,经尿素包合后得到的高纯度多不饱和脂肪酸的总抗氧化能力最强。     

尿素包合法富集驼峰油中不饱和脂肪酸的工艺优化

以精炼驼峰油混合脂肪酸(饱和脂肪酸54. 024 3%,单不饱和脂肪酸34. 645 7%,多不饱和脂肪酸4. 645 3%)为原料,在单因素试验基础上,采用响应面法优化尿素包合法富集其不饱和脂肪酸工艺。结果表明:尿素包合法富集驼峰油中不饱和脂肪酸的最佳工艺条件为尿素质量与95%乙醇体积比3∶8、尿素与混合脂肪酸质量比3. 315∶1、包合温度-2. 37℃、包合时间18. 13 h,在此条件下产物碘值(I)为125. 73 g/100 g,产物中饱和脂肪酸含量为7. 802 5%,单不饱和脂肪酸含量为58. 175 6%,多不饱和脂肪酸含量为17. 322 2%。包合后产物为淡黄色黏稠液态,不饱和脂肪酸含量约为75%。     

尿素包合法富集纯化马齿苋中多不饱和脂肪酸的工艺优化

目的 优化尿素包合法富集纯化马齿苋中的多不饱和脂肪酸的工艺条件。方法 将新鲜马齿苋经索氏提取后所得的脂肪油通过尿素包合的方式富集纯化多不饱和脂肪酸（Polyunsaturated Fatty Acids,简称PUFAs）,并以PUFAs总含量为考察指标,利用高效液相色谱法测定其含量。在单因素试验的基础上采用响应曲面设计对纯化工艺进行优化,对比新鲜马齿苋全草油与纯化物PUFAs理化性质上的区别。结果 尿素包合法富集纯化的最佳工艺为尿素与乙醇体积比1:10,尿素与脂肪酸质量比12:1,结晶温度-20 ℃,此时PUFAs含量预测值为110.76 mg/g,实际值为116.00 mg/g。就理化性质相比较而言,纯化物PUFAs的酸值无显著差异,碘值和过氧化值显著提高,皂化值显著降低（P< 0.05）,表明纯化物PUFAs的不饱和度更高,基本达到本试验的目的。结论 该富集纯化工艺操作简单、方便快捷,适合分离纯化马齿苋脂肪酸类物质,可为马齿苋多不饱和脂肪酸向功能食品方向发展提供参考。     

响应面法优化黑加仑籽油中γ-亚麻酸富集工艺

采用响应面优化尿素包合法富集黑加仑籽油中γ-亚麻酸的最佳工艺。在单因素试验基础上,选择包合温度、尿素/混合脂肪酸配比、95%乙醇/尿素配比(mL/g)、包合时间为考察因素,进行四因素三水平的Box-Behnken中心组合设计,采用响应面法分析4个因素对籽油中γ-亚麻酸含量的影响。结果表明,尿素包合法富集黑加仑籽油中γ-亚麻酸的最佳工艺为包合温度-20℃、尿素/混合脂肪酸配比3.5∶1、95%乙醇/尿素配比2.5∶1(mL/g)、包合时间21h,在此条件下,包合后籽油中γ-亚麻酸含量平均值为24.27%。     

重组白地霉脂肪酶催化菜籽油水解制备α-亚麻酸工艺的研究

利用毕赤酵母GS115表达白地霉的脂肪酶基因,以离子交换法纯化的重组脂肪酶催化菜籽油水解,确定了最佳水解条件为温度42℃,水油比为1.5∶1,p H 8.0,酶用量为250 U/g,反应18 h水解率可达到40.1%。以水解得到的混合脂肪酸为原料,建立一种尿素包合法富集α-亚麻酸的工艺。通过单因素试验对影响尿素包合富集效果的包合温度、时间、溶剂配比进行研究,由正交试验得到包合过程的最佳工艺条件为m(脂肪酸)∶m(尿素)∶V(乙醇)为1∶4∶20,包合温度-20℃、包合时间14 h,此条件可使其中α-亚麻酸的含量由8.03%提高至19.24%。     

红花籽油混合脂肪酸制备及多不饱和脂肪酸富集

红花籽油中含多种脂肪酸，尤其是亚油酸。经皂化后制备混合脂肪酸，用尿素包合法富集红花籽油中多不饱和脂肪酸，多不饱和脂肪酸含量达83.2%。     

蚕蛹油尿素包合物中尿素和脂肪酸的分离回收工艺研究

采用尿素包合法对蚕蛹油中的多不饱和脂肪酸进行富集,为了合理利用资源,实现尿素和脂肪酸的高效回收利用,研究了蚕蛹油尿素包合物中尿素和脂肪酸的分离回收工艺.结果表明最佳工艺条件为:水作溶解尿素包合物的溶剂,在70 ℃固液比为2∶ 1(pH为2～3)的条件下全部溶解,用石油醚萃取出脂肪酸,剩余的尿素溶液在0 ℃下结晶2 h.在此条件下回收率为97.55%,回收的尿素中氮含量达45.9%,脂肪酸组成主要为C16∶ 0(34.16%)、C18∶ 0(12.17%)和C18∶ 1(42.93%)饱和脂肪酸和单不饱和脂肪酸.     

尿素包合法制备油莎豆油中的油酸

以油莎豆油为原料,采用尿素包合法对油酸进行纯化,通过单因素试验和正交试验,研究了尿素包合过程中甲醇浓度,回流时间,m(尿素):m(混合脂肪酸)比,温度T_1和温度T_2等因素对油酸纯度的影响。采用气相色谱-质谱联用(gas chromatography-mass spectroscopy,GC·MS)对纯化后的油莎豆油脂肪酸成分进行了分析。结果表明:采用体积分数85%甲醇,m(尿素):m(混合脂肪酸)=8:10,在N_2保护下于60℃加热搅拌回流15 min,8℃下保存24 h后,滤液再在-10℃下静置24 h,油酸含量可由77.17%提高到90.72%。尿素包合后油莎豆油主要脂肪酸组成为棕榈酸7.49%,油酸90.72%,硬脂酸1.08%。     

尿素包合法富集苦瓜籽油中α-桐酸的工艺优化北大核心CSCD

以超临界CO;萃取的苦瓜籽油为原料,经皂化酸解法制得混合脂肪酸,再采用尿素包合法富集其中的α-桐酸。在单因素试验的基础上,采用正交试验对富集工艺条件进行优化。结果表明,α-桐酸的最佳富集工艺条件为:采用95%乙醇作为尿素溶剂,混合脂肪酸与尿素质量比1∶3,尿素与95%乙醇质量比1∶5,包合温度4℃,包合时间24 h。在最佳工艺条件下,α-桐酸纯度从苦瓜籽油中的28.83%提高至60.03%,产物中共轭亚麻酸相对含量达到71.28%。     

马齿苋全草油的亚临界流体萃取、脂肪酸分析及抗氧化活性

以马齿苋全草油提取率为考察指标,通过单因素实验和正交实验确定亚临界异丁烷萃取技术提取马齿苋全草油的最佳提取工艺;采用气相色谱-质谱联用仪(GC-MS)分析马齿苋全草油的脂肪酸组成,同时通过羟基自由基(·OH)、DPPH·自由基和总抗氧化能力3个体外抗氧化模型评价马齿苋全草油抗氧化活性。结果表明:亚临界异丁烷萃取技术的最优工艺条件为,萃取压力0.8 MPa,萃取温度40℃,萃取时间150 min,提取率达2.91%;GC-MS分析结果表明,马齿苋全草油主要含有33.19%亚油酸(∞-6多不饱和脂肪酸)和31.04%亚麻酸(∞-3多不饱和脂肪酸);并且马齿苋全草油具有明显的总抗氧化活性并且对DPPH·和·OH具有一定的清除能力。     

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。     

花生四烯酸分离纯化方法研究进展

花生四烯酸是人体必需不饱和脂肪酸,具有极高保健价值。该文介绍并比较花生四烯酸分离纯化方法,主要包括低温溶剂结晶法,脲包法,银离子络合法,超临界萃取法,高效液相色谱法等方法。     

Milk fatty acids as possible biomarkers to early diagnose elevated concentrations of blood plasma nonesterified fatty acids in dairy cows

Most cows encounter a state of negative energy balance during the periparturient period, which may lead to metabolic disorders and impaired fertility. The aim of this study was to assess the potential of milk fatty acids as diagnostic tools of detrimental levels of blood plasma nonesterified fatty acids (NEFA), defined as NEFA concentrations beyond 0.6 mmol/L, in a data set of 92 early lactating cows fed a glucogenic or lipogenic diet and subjected to 0-, 30-, or 60-d dry period before parturition. Milk was collected in wk 2, 3, 4, and 8 (n = 368) and blood was sampled weekly from wk 2 to 8 after parturition. Milk was analyzed for milk fatty acids and blood plasma for NEFA. Data were classified as “at risk of detrimental blood plasma NEFA” (NEFA ≥0.6 mmol/L) and “not at risk of detrimental blood plasma NEFA” (NEFA <0.6 mmol/L). Concentrations of 45 milk fatty acids and milk fat C18:1 cis-9-to-C15:0 ratio were subjected to a discriminant analysis. Milk fat C18:1 cis-9 revealed the most discriminating variable to identify detrimental blood plasma NEFA. A false positive rate of 10% allowed us to diagnose 46% of the detrimental blood plasma NEFA cases based on a milk fat C18:1 cis-9 concentration of at least 230 g/kg of milk fatty acids. Additionally, it was assessed whether the milk fat C18:1 cis-9 concentrations of wk 2 could be used as an early warning for detrimental blood plasma NEFA risk during the first 8 wk in lactation. Cows with at least 240 g/kg of C18:1 cis-9 in milk fat had about 50% chance to encounter blood plasma NEFA values of 0.6 mmol/L or more during the first 8 wk of lactation, with a false positive rate of 11.4%. Profit simulations were based on costs for cows suffering from detrimental blood plasma NEFA, and costs for preventive treatment based on daily dosing of propylene glycol for 3 wk. Given the relatively low incidence rate (8% of all observations), continuous monitoring of milk fatty acids during the first 8 wk of lactation to diagnose detrimental blood plasma NEFA does not seem cost effective. On the contrary, milk fat C18:1 cis-9 of the second lactation week could be an early warning of cows at risk of detrimental blood NEFA. In this case, selective treatment may be cost effective.     

膳食中的脂肪酸平衡

本文综述了膳食中三类脂肪酸（饱和脂肪酸、单不饱和脂肪酸及多不饱和脂肪酸）的营养学功能，并就有关膳食脂肪酸的平衡及n-6与n-3的合适比例作了总结。     

东北不同杂豆油脂含量及脂肪酸组成分析

为开发与利用东北杂豆资源,本文以东北特有杂豆为原料,采用气质分析方法对杂豆脂肪含量及脂肪酸组成进行初步分析。结果表明：杂豆中含有丰富的不饱和脂肪酸,且在测定所有杂豆中均是高活性的n:3、n:2类不饱和脂肪酸含量高,而活性相对的n:1类不饱和脂肪酸含量低。芸豆类杂豆的脂肪酸中不饱和脂肪酸含量均大于80%;且高活性的n:3类不饱和脂肪酸含量较多,紫花芸豆的n:3类不饱和脂肪酸含量达到了48.99%,具有进一步开发应用的价值。本研究为东北杂豆的综合利用提供了理论参考与依据     

α-亚麻酸研究进展

α-亚麻酸属于n-3系列多不饱和脂肪酸,分子结构为△9,12,15-18:3,主要来源于陆地植物, 如杜仲、藿香、亚麻、紫苏等。在体内代谢过程中,它主要作为EPA和DHA前体物质,并具有降低胆固醇、血脂,预防心血管疾病、保护视力和抑制过敏反应等功能。该文主要介绍α-亚麻酸的来源、分离提取方法进展及生理功能,并对α-亚麻酸发展前景进行展望。     

Effect of ruminal pulse dose of polyunsaturated fatty acids on ruminal microbial populations and duodenal flow and milk profiles of fatty acids

The objective of this study was to examine the effect of ruminal pulse dose of free linoleic acid (LA) and free docosahexaenoic acid (DHA) on microbial populations in the rumen, duodenal fatty acid (FA) flow, milk composition, and milk FA profiles of Chinese Holstein dairy cows. Four rumen- and duodenal-fistulated Chinese Holstein cows in mid lactation (138.5 ± 10 d in milk) were randomly assigned to 3 treatment groups and 1 control group in a 4 × 4 Latin square design over 4 periods (3 wk per period). Diets contained either no LA or 2.7% LA and either no DHA or 0.5% DHA in a 2 × 2 factorial arrangement of treatments. Ruminal pulse dose with DHA increased counts of Megasphaera elsdenii, decreased Fibrobacter succinogenes, but did not affect Butyrivibrio fibrisolvens or Ruminococcus flavefaciens. The pulse dose of LA at 2.7% dry matter had no effect on the population sizes of the 3 major cellulolytic bacterial species or M. elsdenii, and no interaction was observed between LA and DHA. The pulse dose of LA or DHA, either alone or in combination, increased the duodenal flow of vaccenic acid (VA). The milk VA and cis-9,trans-11 conjugated linoleic acid (CLA) contents also increased in response to the fatty acid pulse dose, and the pulse dose of both LA and DHA together had the most profound stimulatory effect. This study indicated that ruminal pulse dose of LA or DHA could be used to increase duodenal flow of VA and the milk contents of potentially health-promoting FA, such as VA and cis-9,trans-11 CLA. These results might be useful in formulating dietary interventions to improve milk cis-9,trans-11 CLA contents.     

坚果中脂肪含量及脂肪酸组成分析

目的分析16种市售坚果中脂肪含量及脂肪酸组成,比较不同品种坚果间脂肪含量、饱和脂肪酸和不饱和脂肪酸组成的差异。方法采用气相色谱分析法测定坚果中37种脂肪酸的含量,用最小显著性差异法(least-significant difference,LSD)法进行多重比较。结果坚果的平均脂肪含量为(55.6±0.86)g/100 g,变化范围为40.2~71.3 g/100 g,碧根果脂肪含量显著高于其他品种坚果脂肪含量(P0.05);坚果中的不饱和脂肪酸含量为72.77~95.47 g/100 g脂肪,平均值为(86.68±0.12)g/100 g脂肪,显著高于饱和脂肪酸4.53~22.19 g/100 g脂肪,平均值为(11.31±0.16)g/100 g脂肪(P0.05),东北榛子中单不饱和脂肪酸总含量最高,为84.34 g/100 g脂肪,而纸皮核桃中的多不饱和脂肪酸总含量最高,为74.17 g/100 g;坚果中不含短链脂肪酸和中链脂肪酸。结论坚果中不饱和脂肪酸含量较多,富含ω-6和ω-3脂肪酸,营养价值较高。     

近红外光谱法快速检测婴儿配方奶粉中的脂肪酸含量

采用傅里叶近红外光谱结合偏最小二乘法(PLS)法建立了测定婴儿配方奶粉中的总脂肪酸、饱和脂肪酸和不饱和脂肪酸含量的近红外数学模型,并通过交互验证和外部检验两种方式考察了近红外数学模型的可靠性。通过选择不同的波长范围,采用平滑、矢量归一化、一阶求导、二阶求导和散射校正对近红外光谱进行处理,总脂肪酸、饱和脂肪酸和不饱和脂肪酸的校正模型相关系数(R2)分别为0.9337、0.9374、0.9020,RPD分别为3.63、3.65、2.90。结果表明近红外数学模型具有良好的预测性能。采用建立的模型对验证集中的20个婴儿配方奶粉样品进行预测,总脂肪酸含量、饱和脂肪酸和不饱和脂肪酸的预测值与化学测定值之间经配对t检验分析,与常规化学方法得到的检验结果无显著差异。     

Unrestricted feed intake during the dry period impairs the postpartum oxidation and synthesis of fatty acids in the liver of dairy cows

The purpose of this study was to determine the activities of key hepatic enzymes of fatty acid synthesis and oxidation in cows that had excessive body fat at parturition. Dairy cows were allocated to either an experimental group or a control group. All cows were offered a total mixed ration with an energy content of 6.6 MJ of net energy for lactation per kilogram of dry matter and consisting of corn silage, beet pulp, rapeseed meal, and soybean meal. Control cows were restricted to 6.8 kg/dry matter of the mixed ration in the dry period. Experimental cows had unrestricted access to the mixed ration during the dry period to increase body fat and induce fatty liver postpartum. Blood and liver samples were collected 1 wk before and 1, 2, and 4 wk after parturition. Before parturition, neither the serum nonesterifled fatty acids nor the hepatic triacylglycerol concentrations differed between experimental and control cows. After parturition, the values for these variables were greater in experimental cows than in control cows. Plasma 3-hydroxybutyrate increased sharply after parturition in the experimental group. In liver, the activity of acetyl-CoA carboxylase was already significantly lower in the experimental group before parturition. After parturition, the activities of acetyl-CoA carboxylase and fatty acid synthase dropped in the experimental group. The activity of 3-hydroxy-acyl-CoA dehydrogenase in liver was less in experimental cows following parturition. Hepatic citrate synthase activity increased only in the control group after parturition. Unrestricted feed intake before parturition reduces de novo fatty acid synthesis as well as fatty acid oxidation after parturition. The reduction in fatty acid oxidation following parturition may contribute to postpartum accumulation of triacylglycerol in the livers of cows with unrestricted access to feed during the dry period.