油炸过程中3种植物油脂肪酸组分含量及品质的变化

为研究油炸过程中大豆油、山茶油、棕榈油品质的变化,用国标法测定酸价和过氧化值,并利用高极性色谱柱CP-Sil 88对植物油中脂肪酸,特别是反式脂肪酸(TFA)组分和含量的变化进行分析。结果表明:顺式亚油酸(53.06%)、顺式油酸(82.26%)、棕榈酸(49.7%)分别是大豆油、山茶油、棕榈油中主要的脂肪酸。大豆油、棕榈油低温油炸时油脂中总TFA含量不会存在明显变化,平均为15.51mg/g和1.35mg/g。随着油炸时间延长,山茶油中反式油酸含量增加了63.82%。油炸过程中,3种植物油的酸价由高到低依次为山茶油>棕榈油>大豆油,大豆油和棕榈油的过氧化值先增大后减小。在8h连续使用时间内,酸价和过氧化值都未超过煎炸油的卫生标准。综合以上结果,棕榈油中总TFA含量最低,更适合于短时间循环使用的食品加工过程。     

过量表达苹果酸酶对E.coli脂肪酸合成能力的影响

为了考察苹果酸酶对原核生物脂肪酸合成能力的影响,本研究从E.coli K-12中克隆了苹果酸酶基因(NADPME,EC1.1.1.40)MaeB,并插入质粒pET30a-T,构建了重组质粒pMX20,经IPTG诱导在E.coli BL2I(DE3)获得了大量表达.摇瓶发酵结果表明,过量表达苹果酸酶基因会改变大肠杆菌脂肪酸合成能力,并在添加适宜底物苹果酸(15mmol/L)时,胞内总酯含量比受体菌提高了4倍,约197.74mg/g,产率为1.89％.本研究为脂肪酸生产提供了优良菌株,具有一定的应用开发前景.     

羟基脂肪酸生产菌Bacillus pumilus对油酸的代谢特性和产物分析

一株具有转化油酸羟基化的微生物Bacillus pum ilus BD-12(记作BP BD-12),在摇瓶条件下分批深层培养,研究了菌株在以胰蛋白胨为主要氮源、葡萄糖为基本碳源的条件下对油酸(OA)的代谢特性,并对转化OA生成羟基脂肪酸的规律及产物进行了分析测定。结果表明:在只有葡萄糖作碳源条件下,细胞生长良好,且无羟基脂肪酸生成,OA对菌株BP BD-12细胞生长有抑制作用;用40 h细胞菌龄添加OA条件下其转化产物为ω-1、ω-2和ω-3-羟基脂肪酸,其转化率和羟基脂肪酸得率最大值分别达到63%和12.3%;通过气质联用方法对产物组分分析,其ω-1-羟基脂肪酸占总羟基脂肪酸的70%,细胞培养过程中未有其它羟基脂肪酸检出。因此,菌株BP BD-12是一株较理想的ω-1-羟基脂肪酸工业化生产菌株。     

蓖麻油快速甲酯化方法及其脂肪酸含量分析

对40份蓖麻品种蓖麻籽的百粒重、出仁率、含油率、不同脂肪酸含量及蓖麻油快速甲酯化方法进行了研究.结果表明:不同品种蓖麻籽的百粒重、含油率及主要脂肪酸蓖麻油酸的含量差别较大,百粒重变化范围为:21.42～86.77 g,出仁率较为集中,均在72.61%～79.48%之间,含油率变化范围为:45.72%～57.48%;蓖麻油主要含有蓖麻油酸、油酸、亚油酸及少量的棕榈酸、硬脂酸,蓖麻油酸、油酸、亚油酸的变化范围依次为:81.46%～90.24%、2.83%～6.13%、4.29%～7.82%,棕榈酸、硬脂酸含量均为1%左右;蓖麻油快速甲酯化条件为:蓖麻油用量(＜70 mg),KOH-CH3OH浓度0.5 mol/L,用量0.2 mL,室温下甲酯化2 min.     

响应面法优化重组谷氨酸棒杆菌G-BC产脂肪酸的培养条件北大核心CSCD

乙酰辅酶A羧化酶是谷氨酸棒杆菌中调控脂肪酸合成的关键酶。为了研究乙酰辅酶A羧化酶α亚基(accBC)基因对脂肪酸合成的影响,以accBC表达的菌株重组谷氨酸棒杆菌G-BC为材料,研究了诱导剂异丙基-β-D-硫代半乳糖苷(IPTG)浓度、培养时间、培养温度对重组谷氨酸棒杆菌G-BC脂肪酸产量的影响,并通过响应面法优化了重组谷氨酸棒杆菌G-BC产脂肪酸的培养条件,同时与原始菌株脂肪酸产量进行了对比。结果表明:重组谷氨酸棒杆菌G-BC产脂肪酸的最佳条件为诱导剂浓度1 mmol/L、培养时间20 h、培养温度32℃,在此条件下脂肪酸产量为34.56 mg/g(以菌体干质量计),比原始菌株提高了1.68倍。说明乙酰辅酶A羧化酶α亚基对于谷氨酸棒杆菌合成脂肪酸有促进作用。     

棕榈油中脂肪酸组成的气相色谱—质谱分析

将棕榈油经甲酯化处理,并用总离子流色谱峰的峰面积进行归一法定量分析其脂肪酸成分,鉴定出肉豆蔻酸、棕榈酸、硬脂酸、油酸和亚油酸等5种脂肪酸。其中油酸、亚油酸含量超过50%,显示有较高的食用价值。同时利用棕榈油脂肪酸组成的显著特征,为鉴别油脂掺假掺伪进一步研究提供依据。     

南果梨果实各部位脂肪酸组成GC-MS分析

采用索氏提取法对南果梨籽、果皮和果肉的脂肪酸成分进行提取,并用气相色谱- 质谱联用技术(GC-MS)进行分析,经峰面积归一法并通过G1701BA 化学工作站数据处理系统得出各部位脂肪酸成分组成。结果表明：南果梨籽含14 种脂肪酸,分别为癸酸(0.05%)、棕榈油(0.29%)、14- 甲基十五烷酸(0.38%)、棕榈酸(9.08%)﹑ 14- 甲基十七碳酸(0.12%)、亚油酸(55.64%)、油酸(27.18%)、硬脂酸(2.23%)、花生烯酸(0.77%)、花生酸(1.85%)、二十一碳酸(0.19%)、山嵛酸(0.38%)、二十三碳酸(0.06%)和木焦油(0.15%),占检出总量的98.37%;果皮含4 种脂肪酸,分别为棕榈酸(6.79%)﹑亚油酸(9.65%)﹑油酸(33.73%)、硬脂酸(1.51%),占检出总量的51.68%;果肉含3种脂肪酸,分别为棕榈酸(4.59%)﹑亚油酸(22.81%)﹑油酸(15.87%),占检出总量的43.27%。其不饱和脂肪酸以亚油酸、油酸为主。     

反棕榈油酸对人肝细胞脂质的影响

流行病学研究报道反刍动物代表性反式脂肪酸反棕榈油酸(9t16∶1)具有降低血脂的作用,为了进一步研究9t16∶1对细胞脂质代谢的影响,采用不同浓度反棕榈油酸作用于脂肪变性人肝细胞LO2,通过测定细胞存活率、细胞脂肪酸组成、脂质含量变化以及细胞氧化情况反映反棕榈油酸对脂质代谢的作用。结果表明:100μmol/L的9t16∶1作用于人肝细胞后饱和脂肪酸含量降低了34.89%,单不饱和脂肪酸含量升高了16.44%,多不饱和脂肪酸含量升高了30.50%;9t16∶1在人肝细胞内部分生物转化为11t18∶1和CLA,其转化率分别为17.50%和16.42%;9t16∶1显著降低脂肪变性人肝细胞甘油三酯和胆固醇含量,降低率分别为61.76%和37.80%;9t16∶1显著升高人肝细胞MDA水平(升高率为45.36%)和降低SOD活力(降低74.42%),促进细胞内脂质氧化。因此,反棕榈油酸可通过促进人肝细胞脂质氧化达到降低脂质堆积的作用。     

东北野生榛蘑中的脂肪酸分析

采用索氏提取法对东北野生榛蘑中脂肪酸进行了提取,以石油醚为萃取剂,用甲醇-浓硫酸进行甲酯化,气相色谱-质谱法分析测定了其中脂肪酸的组成及相对含量。共检测出11种脂肪酸,主要为油酸32.11%、亚油酸31.75%、棕榈酸13.80%和棕榈油酸11.33%,其不饱和脂肪酸占总脂肪酸的82.05%。     

低温溶剂分提与分子蒸馏复合法富集沙棘果油棕榈油酸的工艺研究

以沙棘果油水解后的混合脂肪酸为原料,在正己烷-丙酮(体积比1∶1)与粗制混合脂肪酸体积比1∶1、分提温度-5℃、分提时间12 h下采用低温溶剂分提法富集棕榈油酸,再采用分子蒸馏法对低温分提混合脂肪酸进行富集,以达到富集沙棘果油棕榈油酸的目的。通过单因素试验对分子蒸馏条件进行优化,得到最佳的分子蒸馏工艺条件为真空度5 Pa、蒸馏温度95℃、进料速度1 mL/min、刮膜器转速220 r/min。在最佳条件下进行二次分子蒸馏,棕榈油酸含量从沙棘果油的30. 74%提高到72. 56%,轻相得率为30. 90%。进一步将产物进行低温溶剂分提后,棕榈油酸含量可达78. 30%。     

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.     

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.     

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.     

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。     

Amino acid and fatty acid composition of cane molasses.

Cane molasses contain both protein and non-protein amino acids and fatty acids. Gas chromatographic evidence is presented for aspartic and glutamic acids and alanine, being the major acids out of the 18 protein amino acids determined. Two unidentified N-containing free acids, eluting faster than alanine and other protein amino acids on EGA column, are of particular interest. Linoleic (C18:2) is by far the most important fatty acid found. Other major fatty acids are palmitic (C16:0), oleic (C18:1) and arachidic (C20:0).     

油桐种子脂肪酸及氨基酸分析

采用索氏提取法提取油桐种子中的油脂,经甲酯化处理后用气相色谱-质谱联合分析法测定脂肪酸组成及含量,利用氨基酸自动分析仪测定氨基酸组成及含量。油桐种子油脂含量为65.65%,其中含有39种脂肪酸,主要成分为油酸(30.62%)、亚油酸(19.36%)、棕榈酸(13.97%)、十八酸(13.76%)等,不饱和脂肪酸含量高达55.09%;油桐种子粗蛋白含量36.73%,主要含有17种氨基酸,而必需氨基酸占氨基酸总量的33.89%。油桐种子是1种有很高利用价值的可开发资源。     

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.     

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%)。