响应面优化脂肪酶催化合成中长碳链甘三酯

采用响应面设计对脂肪酶Novozym 435在无溶剂体系中催化甘油和中长碳链脂肪酸(辛酸、癸酸和油酸混合物)酯化反应合成中长碳链甘三酯进行了研究.研究发现:反应温度、加酶量和反应时间对中长碳链甘三酯得率具有显著性影响(P＜0.05),而底物摩尔比(脂肪酸与甘油摩尔比)对中长碳链甘三酯得率不具有显著性影响.优化得到的最佳条件为:反应温度90℃,加酶量6.5％(以脂肪酸和甘油的总质量计),底物摩尔比3.5∶1,反应时间12.97 h.在此条件下,平均甘三酯得率为78.5％;产品中甘三酯、甘二酯、甘一酯和游离脂肪酸含量分别为85.6％、0.3％、0.1％和14.0％;产品甘三酯中辛酸、癸酸和长碳链脂肪酸含量分别为25.4％、10.7％和63.9％,与目标中长碳链甘三酯产品指标基本一致.     

液-质联机分析牛脂甘油酯组成及结构

采用皂化/甲酯化GC-MS分析牛脂的脂肪酸组成,主要为棕榈酸(39.86%)、油酸(37.58%)、硬脂酸(11.14%)。采用反相高效液相色谱(RP-HPLC)-大气压化学电离质谱(APCI-MS)及电喷雾电离质谱(ESI-MS)分析牛脂的甘油酯组成,根据ESI准分子离子,APCI准分子离子、二酰基甘油碎片离子、离子阱碰撞诱导解离形成的二级质谱,以及甘油酯在反相色谱上出峰的等价碳原子数原则,并结合脂肪酸组成分析,鉴定出26种甘油酯,包括7种甘二酯和19种甘三酯,其中含量较高的为1-棕榈酸-2-油酸-3-亚油酸甘三酯(11.74%)、1-油酸-2,3-二亚油酸甘三酯(10.97%)、1,3-二油酸-2-亚油酸甘三酯(10.25%)。     

基于脂肪酸和甘三酯组成的茶油掺伪检测参数的确定

本实验研究了测定脂肪酸和甘三酯在检测茶油中掺伪4种其他植物油时的有效性。在本研究中,与脂肪酸和甘三酯指纹图谱向量夹角余弦相似度、亚麻酸相对含量、三亚油酸甘油酯(LLL)相对含量、碳当量数(ECN)42甘三酯的实际与理论含量绝对差(ΔECN42)值、(LLL/ECN42)×100值和ECN46/LLL值相比,(ECN44+ECN46)/LLL值是茶油中掺伪大豆油、葵花籽油和玉米油的最有效检测参数,分别可以检测茶油中掺伪3.35%的大豆油、1.73%的葵花籽油和3.01%的玉米油,亚麻酸相对含量是茶油中掺伪芥花籽油的最有效检测参数,可以检测茶油中掺伪7.55%的芥花籽油。     

酸性离子液体催化合成中碳链甘三酯的研究

在无溶剂体系下,采用离子液体—1-甲基-3-磺丙基咪唑硫酸氢盐[Spmim][HSO4]催化甘油和中碳链脂肪酸(辛酸和癸酸混合物)酯化合成中碳链甘三酯.在单因素实验基础上,采用响应面设计对反应条件进行优化,得到最佳反应条件为:反应温度160℃,反应时间14.03 h,催化剂加入量(以脂肪酸和甘油的总质量计)0.74％,底物摩尔比(脂肪酸与甘油摩尔比)3.2∶1.在最佳工艺条件下,中碳链甘三酯的得率为92.90％,酯化率为95.48％,产物中甘二酯、甘一酯和游离脂肪酸含量分别为2.38％、0.21％和4.51％.     

对食用油脂与健康的新认识、新看法

食品中的油脂总称为食品脂质,脂质包括脂肪酸二甘油酯（以下简称甘三酯）和类脂（磷脂、固醇等）,甘三酯是食用油脂的主要成分。膳食中油脂的来源主要有动物性脂肪和植物油,陆生动物脂肪的甘三酯含高比例的饱和脂肪酸,室温下呈固态;绝大部分植物油的甘三酯含较多不饱和脂肪酸,室温下呈液态;某些海洋鱼油中,其甘三酯含高比例多不饱和脂肪酸,室温下也呈液态。食用油脂中多种脂肪酸都是直链和偶数碳原子的,碳链长度从４个到２４个不等,但主要脂肪酸是１６、１８、２０和２２个碳原子构成的,常见的食用油脂的脂肪酸见下表：食品脂质…     

无溶剂体系中酶促合成中碳链甘三酯

在无溶剂体系下,采用Lipozyme 435催化甘油和中碳链脂肪酸(辛酸和癸酸混合物)酯化合成中碳链甘三酯(MCT).结果表明在无溶剂体系下,反应温度对MCT得率具有显著影响.通过单因素试验和正交试验,得出制备MCT的最佳工艺条件为:反应温度90℃,加酶量(以脂肪酸质量计)5％,底物摩尔比(脂肪酸与甘油摩尔比)3∶1,反应时间16 h.在此条件下,MCT得率为92.10％,产物中甘二酯、甘一酯和游离脂肪酸含量分别为6.03％、0.13％和1.74％.     

钙盐和蛋白质配比对1,3-二油酸-2-棕榈酸甘油酯乳液体外消化的影响

利用体外模拟胃肠消化系统,考察酪蛋白和乳清蛋白的不同比例和矿物质含量及两者相互作用对1,3-二油酸-2-棕榈酸甘油酯（1,3-dioleoyl-2-palmitoylglycerol,OPO）消化的影响,并对体外消化后的脂肪酸释放率、粒度分布和脂肪酸组成进行测定。结果表明,胃消化阶段,相同乳化剂配比,OPO型乳液脂质生物利用率随CaCl2浓度增加而增加;且在20 mmol/L CaCl2浓度下,不同蛋白质配比（乳清蛋白-酪蛋白）,乳液体外消化过程中游离脂肪酸（free fatty acid,FFA）释放率大小顺序为：10∶0＞6∶4＞0∶10。体外模拟脂质消化前后平均粒径分析结果显示,在不同CaCl2浓度影响下,胃肠消化后乳液平均粒径大于新鲜乳液;随Ca2＋浓度增加,新鲜乳液d（0.1）、d（0.5）、d（0.9）值均增加,且在加胃肠消化液后,平均粒径显著增大。在肠消化阶段,3 组乳液在不同CaCl2浓度下,FFA释放速率及程度均随CaCl2浓度增加而增加。胃肠消化后的产物FFA和单甘酯组成分析表明：乳液消化后,FFA和单甘酯主要由棕榈酸和油酸组成。除此之外,本实验还考察了不同钙盐对OPO乳液脂质消化的影响,结果表明溶解度高的钙盐加速脂质水解,有利于脂肪酸的释放即在肠消化阶段FFA释放速率和程度次序为：柠檬酸钙＞氯化钙＞乳酸钙＞碳酸钙。     

甘三酯立体专一分析的研究 (Ⅰ)甘三酯“立体专一分析”对研究甘三酯组份的重要性

有关用油脂的脂肪酸组成推算其甘三酯组份的假说很多,但用之比较有效的仅有两种,即Vander Wal的2—随机1,3—随机假说与Tsuda的1随机2随机3随机假说。前者以甘三酯2位脂肪酸分布为基础,而后者则是以甘三酯“立体专一分析”数据为基础,因此后者更比较符合天然油脂的实际。本文综合介绍了有关甘三酯“立体专一分析”的涵义、反应机制、操作程序以及研究甘三酯组份的重要性。     

油茶籽油甘三酯组成的NARP-HPLC-EISD分析及其在高温处理过程中的降解研究

油茶籽油甘三酯在优化条件下得到良好分离,在14种甘三酯中含量水平前三的分别为OOO+SLO(74.21%)、OOP(10.64%)和OOL+SLL(5.19%)。方差分析表明来自不同产地的油茶籽油甘三酯分布情况存在差异。油茶籽油在深层煎炸过程(180℃)中甘三酯的总体损失率为47.85%,ECN40、ECN_(42)、ECN_(44)、ECN_(46)、ECN_(48)和ECN_(50)区的甘三酯损失率分别为86.73%、91.52%、75.97%、45.01%和55.30%。LLL和PPL历经40 h煎炸后完全降解。与深层煎炸油样相比,加热(180℃)样品中甘三酯的降解程度相对降低。偏相关分析表明油茶籽油甘三酯在深层煎炸过程中的降解速率与极性组分的生成速率呈负相关。     

超声和酶处理对乳化猪油体外消化特性的影响

本研究以猪油为原料,超声诱导脂肪晶体发生重排,采用谷氨酰胺转氨酶（transglutaminase,TG）交联 浓缩乳清蛋白作为乳化剂,制备改性乳化猪油,进而探讨乳化猪油未吸附蛋白含量的变化,并在体外消化模型中以 平均粒径、Zeta电位、游离脂肪酸释放量以及脂肪颗粒微观结构作为评价指标,对改性乳化猪油体外消化特性进行 研究。结果表明,超声和TG处理分别对乳化猪油产生不同的作用,超声处理后乳化猪油未吸附蛋白含量低于未处 理样品,乳化稳定性降低,而TG处理则提高了乳化猪油的乳化稳定性。超声处理后的乳化猪油在体外消化过程中 的游离脂肪酸的释放量、平均粒径显著高于未处理样品（P＜0.05）,Zeta电位明显低于未处理样品。而TG交联浓 缩乳清蛋白促使乳化猪油颗粒更加细小,在体外消化过程中游离脂肪酸的释放量显著降低（P＜0.05）。超声处理 的乳化猪油更易于消化,TG处理则减缓了乳化猪油的消化速率。     

Flavor production from edible oils and their constituents by Penicillium corylophilum

Production of volatile substances from edible oils and their constituents by Penicillium corylophilum was studied to clarify the mechanism of flavor production from a non-stick oil by the organism in a rice cake system. First, edible oils from plant and animal origins were tested for flavor production. Among the oils tested, coconut oil was the only one from which the flavor was produced. Second, triacylglycerols consisting of fatty acids with various lengths of carbon chain (C6 to C13) were studied for flavor production. Among the triacylglycerols tested, flavors were produced from those consisting of fatty acids with carbon chains of C6 to C11. The flavors consisted of methylketones and secondary alcohols, whose carbon chains were one carbon shorter than the precursor fatty acid molecules of the triacylglycerols. Flavors similar to that from the non-stick oil were produced from tricaprylin (C8), trinonanoin (C9), and tridecanoin (C10) among the triacylglycerols tested. Formation of mould spores was more strongly suppressed by triacylglycerols with shorter chain fatty acids. Third, fatty acids with various lengths of carbon chain (C7 to C15) were studied for flavor production. Among the fatty acids tested, flavors were produced from decanoic (C10) and undecanoic (C11) acids only. The flavors also consisted of methylketones and secondary alcohols one carbon shorter than the precursor fatty acids. Fatty acids with short carbon chains (C7 to C9) completely inhibited the mould growth. Our study showed that the range of carbon chain length of fatty acids capable of the flavor production (C10 to C11) was narrower than that of triacylglycerols (C6 to C11). It was also found that the non-stick oil and coconut oil contain tricaprylin and tridecanoin as triacylglycerols and decanoic acid as fatty acid.     

An extracellular lipase from the dimorphic yeast Arxula adeninivorans: molecular cloning of the ALIP1 gene and characterization of the purified recombinant enzyme

The lipase-encoding Arxula adeninivorans ALIP1 gene was isolated using fragments of lipase isolates obtained by trypsin digestion for the definition of oligonucleotide primers in a PCR screening approach. The gene harbours an ORF of 1347 bp encoding a 420 amino acid protein of some 50 kDa preceded by an N-terminal 28 prepro-secretion sequence. The deduced amino acid sequence was found to be similar to the lipases from Candida albicans and C. parapsilosis (34-38% identity) and more distantly related to other lipases. The sequence contains the consensus pentapeptide motif (-Gly-X-Ser-X-Gly-) that forms a part of the interfacial lipid recognition site in lipases. The expression of the gene is regulated by carbon source. In media supplemented with Tween 20, induction of the ALIP1 gene and accumulation of the encoded lipase in the medium is observed, thus demonstrating gene regulation by lipophilic compounds. The enzyme characteristics are analysed from isolates of native strains as well as from those of recombinant strains expressing the ALIP1 gene under control of the strong A. adeninivorans-derived TEF1 promoter. For both proteins a molecular mass of 100 kDa was determined, indicating a dimeric structure, a pH optimum at pH 7.5 and a temperature optimum at 30 degrees C. The enzyme hydrolyses all ester bonds in all triglyceride substrates tested. Middle-sized chain fatty acids are more efficiently hydrolysed than short- and long-chain fatty acids, with the highest activity on C8/C10 fatty acid esters pNP-caprylate, pNP-caprate and tricaprylin.     

Influence of lipid type on gastrointestinal fate of oil-in-water emulsions: In vitro digestion study

The potential gastrointestinal fate of oil-in-water emulsions containing lipid phases from different sources was examined: vegetable oils (corn, olive, sunflower, and canola oil); marine oils (fish and krill oil); flavor oils (orange and lemon oil); and, medium chain triglycerides (MCT). The lowest rates and extents of lipid digestion were observed for emulsified flavor oil, followed by emulsified krill oil. There was no appreciable difference between the final amounts of free fatty acids released for emulsified digestible oils. Differences in the digestibility of emulsions prepared using different oils were attributed to differences in their compositions, e.g., fatty acid chain length and unsaturation. The particle size distribution, particle charge, microstructure, and macroscopic appearance of the emulsions during passage through the simulated GIT depended on oil type. The results of this study may facilitate the design of functional foods that control the digestion and absorption of triglycerides, as well as the bioaccessibility of hydrophobic bioactives.     

布那迪栅藻异养培养条件的优化和生化组成含量分析

研究了布那迪栅藻(Scenedesmus bernardii)异养培养条件及不同碳源、氮源对其生化组成的影响。结果表明:异养培养时所需的最佳碳源为葡萄糖,其最适质量浓度为50.0 g/L;最佳氮源为酵母提取物,其最适质量浓度为2.7 g/L;摇瓶培养时所获得的最大生物量达24.8 g/L。布那迪栅藻异养培养时细胞内主要积累碳水化合物,其含量达到细胞干重的58.2%,最高产率为1.05 g/(L·d);其次积累总脂,含量为细胞干重的30.9%,最高产率为0.64 g/(L·d)。     

不同饱和度脂肪酸豆甾醇酯的体外生物可给率北大核心CSCD

为了探究脂肪酸饱和度对其植物甾醇酯生物可给率的影响,采用体外模拟消化静态模型,系统研究了油酸豆甾醇酯、亚油酸豆甾醇酯和亚麻酸豆甾醇酯的体外模拟消化规律。结果表明:体外模拟消化结束后(120 min),亚油酸豆甾醇酯游离脂肪酸(FFA)释放率最高,为78.51%,其次是亚麻酸豆甾醇酯,为74.21%,油酸豆甾醇酯FFA释放率最低,为69.15%;3种豆甾醇酯的水解速率由大到小为亚麻酸豆甾醇酯>亚油酸豆甾醇酯>油酸豆甾醇酯;3种豆甾醇酯的水解度由大到小为亚油酸豆甾醇酯>亚麻酸豆甾醇酯>油酸豆甾醇酯;油酸豆甾醇酯、亚油酸豆甾醇酯和亚麻酸豆甾醇酯生物可给率分别为14.01%、11.11%和10.19%,总体差异较小。综上,豆甾醇酯中结合态的脂肪酸(相同碳链长度)饱和度影响其水解速率,但对豆甾醇酯生物可给率影响较小。     

脂肪酸链长对高直链玉米淀粉—脂质复合物结构及理化性质的影响

目的：探究淀粉—脂质复合物的形成机理。方法：采用12~18个碳链的脂肪酸与脱支/非脱支高直链玉米淀粉复合,利用差示扫描量热仪、X-射线衍射仪、傅里叶红外光谱仪等分析复合物的热特性、结晶结构及有序结构等,探究脂肪酸链长及脱支/非脱支高直链玉米淀粉对淀粉—脂肪酸复合物结构及性质的影响。结果：脱支处理的淀粉与脂肪酸的复合率随碳链的增长而降低,其中月桂酸复合率最高(15.00%);未脱支处理的淀粉与脂肪酸的复合率随碳链的增长先升高后下降,其中软脂酸复合率(13.73%)最高。复合物的热特性、结晶结构、分子有序度等与其复合程度有关,淀粉和脂肪酸复合后,糊化峰值温度升高,热稳定性升高,经复合后,淀粉由B型结晶结构转变为V型。结论：脂肪酸链长及淀粉脱支对淀粉—脂质复合物结构及理化性质具有较大影响。     

Association of plasma insulin concentration to fatty acid distribution between milk fat and membrane synthesis

We examined the association between plasma insulin concentration and fatty acid distribution to milk fat and membrane fractions (triglyceride and phospholipid, respectively) in dairy cows. Thirty-seven Holstein cows at 60 to 70 d postpartum were synchronized by 2 PGF(2α) injections 14 d apart. Plasma samples were taken before morning and evening milkings and milk samples were obtained at morning milking. Plasma insulin concentrations were determined and cows were retrospectively assigned to low insulin (LI; 2.8±0.2 ng/mL, n=6) or high insulin (HI; 5.9±0.6 ng/mL, n=7) experimental groups. Fatty acid analysis of milk samples demonstrated a possible association between plasma insulin concentration and the fatty acid composition in phospholipid and triglyceride fractions. In the HI group, monounsaturated fatty acid concentration tended to be higher in the triglyceride (Tg) fraction than the phospholipids (Pl) fraction. In the LI group, the concentrations of short- and medium-chain saturated fatty acids (<16 carbon chain length), considered de novo-synthesized fatty acids, were higher in the triglyceride fraction than the phospholipid fraction. These results imply that the primary source of saturated fatty acids for phospholipid synthesis, in both HI and LI groups, is the circulation, as reflected by a higher concentration of longer saturated fatty acids (>16 carbon chain length) in the phospholipid fraction. Finally, the phospholipid-to-triglyceride ratio was higher in the HI group than in the LI group. Together, the results indicate that fatty acid distribution between phospholipid (membrane) and triglyceride (fat) synthesis by the mammary gland is associated with fatty acid length, degree of unsaturation, and origin, and might be subject to metabolic hormone regulation. Furthermore, a lower triglyceride-to-phospholipid ratio in the HI group implies that high plasma insulin and low milk fat concentrations are associated with a shift in the size distribution of milk fat globules.     

鳙鱼头汤中微/纳胶粒的体外消化特性及加工条件的影响

通过体外消化模型探究鳙鱼头汤中微/纳胶粒（micro/nano-sized colloidal particles,MNCPs）的消化特性及加工条件对其消化特性的影响。结果显示,加盐和均质未改变汤中MNCPs在消化过程中的整体变化趋势,鳙鱼头汤、加盐鳙鱼头汤和均质鳙鱼头汤中MNCPs在胃消化阶段,均表现为MNCPs膜上蛋白质被降解,脂滴释放并聚集。在小肠消化阶段,脂滴破散,MNCPs聚集体发生裂解;加盐后,MNCPs的平均粒径减小,但存在部分破乳现象并降低了总脂肪酸释放率;均质后,MNCPs的平均粒径进一步减小,MNCPs重新排布,改变了原有膜结构,增加了MNCPs中脂质和酶的接触位点,促进脂肪酸释放,在一定程度上弥补了加盐后鳙鱼头汤中部分脂肪酸释放率的降低。因此,盐和均质引起的MNCPs组成和微观结构的变化是导致MNCPs消化差异的主要原因。     

Fatty acids released from cream by psychrotrophs isolated from bovine raw milk

The ability of 15 psychrotrophic strains to release fatty acids C‐8:0 to C‐20:1 from cream by GC/MS and the substrate specificity of their lipases against selected triacylglycerols (TAG) were studied. The free fatty acids (FFAs) detected in the highest quantities were, in general, those of long (C‐16; C‐18) and intermediate (C‐12; C‐14) even‐numbered carbon chain and unsaturated C‐18:1 and C‐18:2. The ability of lipolytic strains to release fatty acids from milk fat varies according to the bacterial genus, among species and even with the strain of a given species. TAG breakdown by psychrotrophs may occur in a greater or lesser extent, but type and amount of released FFAs are not easily predictable. Pseudomonas rhodesiae showed the highest hydrolytic resistance towards all tested fatty acid triglycerides.     

Lipid accumulation and growth characteristics of Chlorella zofingiensis under different nitrate and phosphate concentrations

To evaluate the potential of the green agla Chlorella zofingiensis as a feedstock for biodiesel production, the effects of nitrogen and phosphate on lipid accumulation and growth of C.?zofingiensis were studied. The maximum specific growth rate (μ(max)) reached 2.15?day(-1) when the concentration of NaNO(3) and K(2)HPO(4)·3H(2)O was 1.0?g?L(-1) and 0.01?g?L(-1), respectively. The lipid contents of C.?zofingiensis grown in media deficient of nitrogen (65.1%) or phosphate (44.7%) were both higher than that obtained from cells grown in full medium (33.5%). The highest lipid productivity (87.1?mg?L(-1)?day(-1)) was also obtained from cells grown in nitrogen deficient media, indicating nitrogen deficiency was more effective than phosphate deficiency for inducing lipid accumulation in C.?zofingiensis. In addition, the feasibility of cultivating the alga in 60?L flat plate photobioreactors and 10?L bottles outdoors for biodiesel was also tested. It was found that C.?zofingiensis could adapt to fluctuating temperatures and irradiance of outdoors and the highest μ(max) and lipid productivity could reach 0.362?day(-1) and 26.6?mg?L(-1) day(-)(1) outdoors, respectively. The lipid production potential of C.?zofingiensis is projected to be 31.1?kg?ha(-1)?day(-1) in outdoor culture. These results suggested that C.?zofingiensis is a promising organism for feedstock production of biofuel and can be used in scaled up culture outdoors.