不同饱和度的三酰甘油酯的共存对胆固醇氧化的影响

为了评价三酰甘油酯的不同饱和程度对胆固醇氧化的影响,将精制的沙丁鱼油三酰甘油酯(碘价IV=182.6)、部分氢化沙丁鱼油三酰甘油酯(IV=174.5)、全氢化沙丁鱼油三酰甘油酯(IV=92.0)分别与胆固醇混合,制成CST、CTPH和CTFH三组试样,在25℃避光处诱导其氧化。研究结果表明:试样的氧化稳定性随着上述各试样的不饱和程度的增加而降低。CST的过氧化物诱导期比CTPH的短,并且在较短的诱导期内CST中组成沙丁鱼油三酰甘油酯的高度不饱和脂肪酸(PUFA)比CTPH的明显减少。各试样中生成的主要胆固醇氧化物有7-β-羟基胆固醇、7-酮基胆固醇、β-环氧化胆固醇和胆甾烷三醇。胆固醇氧化物的生成量随着过氧化物价(POV)的变化和PUFA的减少而增加。胆固醇的氧化与共存的鱼油三酰甘油酯的自动氧化有关。尽管在胆固醇氧化物生成阶段,降低鱼油三酰甘油酯的不饱和度可有效地延缓胆固醇的氧化,但是在诱导期以后胆固醇的氧化速率与CST和CTPH中PUFA的比例无关。     

油脂

甘油酯的不饱和脂肪酸的位置 对三甘酯氧化速率的影响 本文探讨了在50℃下,甘油酯的不饱和脂肪酸位置对三甘酯氧化速率的影响。将饱和的与不饱和的单种脂肪酸的甘油酯,用甲醇钠作催化剂,进行不规则的交酯化而得到不规则的甘油酯。所用的单种甘油酯为三棕榈酸甘油酯、三硬脂酸甘油酯、三油酸甘油酯和三亚油酸甘油酯。应用高效液相结合气相色谱法和酶水解,可分析不规则三甘油酯的分子结构。用气相色谱法测定氧吸收量,结果发现     

三种食用油及三油酸甘油酯对小鼠血脂水平的影响

分别用含猪油、花生油、橄榄油或三油酸甘油酯的高胆固醇乳剂或单用高剂量食用油给小鼠灌服,比较各油脂对血脂的影响。结果表明,灌服含各食用油或三油酸甘油酯的高胆固醇乳剂后,小鼠血清总胆固醇(TC)、肝脏指数明显升高,血清总甘油三酯(TG)含量降低。单独灌服食用油后,三种油均引起小鼠TC水平升高;三种油和三油酸甘油酯均引起血清高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)水平升高,体重增加;除花生油外,其他油脂均升高肝脏指数。猪油、花生油和橄榄油与胆固醇合用均引起血中总胆固醇的升高;高油摄入并未引起高甘油三酯血症;花生油不易使脂质在肝脏积聚;三油酸甘油酯单独使用升高TC作用不明显,和胆固醇合用后其对血中总胆固醇的升高未见有改善作用。     

罗非鱼油的制取工艺及其氧化防止方法

以罗非鱼的鱼内脏为研究对象 ,采用钾盐蒸煮法从罗非鱼内脏中提取鱼油的工艺条件和纯化不饱和脂肪酸 (PUFA)的方法 ,对精制鱼油的氧化性及人工合成抗氧化剂 (TBHQ)、VE、茶多酚 3种抗氧化剂对鱼油的抗氧化性能进行了研究 .通过正交试验及对比试验 ,结果表明 ,从罗非鱼内脏中制取鱼油的最佳工艺条件 :水解温度 70～ 80℃ ,水解时间 4 0min ,KNO3用量 6 g/dL ,盐析时间 10min ;采用低温 钾盐乙醇法纯化鱼油PUFA的效果比尿素包埋法好 ;TBHQ、VE、茶多酚 3种抗氧化剂对鱼油抗氧化作用以茶多酚效果最好     

胆固醇在三硬脂酸甘油酯和三油酸甘油酯中的高温氧化特性

为了阐明组成三酰甘油的脂肪酸是否饱和对胆固醇氧化的影响,使用气相色谱-质谱联用技术研究了胆固醇在三硬脂酸甘油酯(GTS)和三油酸甘油酯(GTO)中的氧化情况,并同步跟踪过氧化值的变化。结果表明:胆固醇在GTS和GTO中的主要氧化产物为7α-羟基胆固醇、7β-羟基胆固醇、5,6β-环氧基胆固醇、5,6α-环氧基胆固醇、7-酮基胆固醇。在160℃加热条件下,胆固醇氧化产物随时间先增加后减少,未氧化胆固醇逐渐减少,在GTO中过氧化值在加热1 h出现最大值(500.46 meq/kg),在GTS中过氧化值在加热3 h出现最大值(401.30 meq/kg),随后逐渐降低。在110℃加热条件下,胆固醇在GTS中不会氧化,过氧化值亦较低,加热96小时出现最大值(278.43 meq/kg),胆固醇在GTO中几乎完全氧化,过氧化值迅速增加,最大值出现在加热12 h(1486.88meq/kg),随后逐渐减少。总的来说,160℃和110℃加热条件下,胆固醇在GTS中比在GTO中稳定,过氧化值的产生亦会延迟且生成量较小,因此,饱和脂肪酸三酰甘油更有助于保持胆固醇在高温下的稳定性。     

不同媒介环境下胆固醇的高温氧化特性研究

目的:研究空气、脂肪酸(硬脂酸、油酸)、食用油(猪油、玉米油)等不同媒介环境条件下,胆固醇的高温氧化特性。方法:采用气相色谱检测胆固醇及其在高温(180℃)条件下的主要氧化产物(7α-羟基胆固醇、7β-羟基胆固醇、5,6β-环氧基胆固醇、5,6α-环氧基胆固醇、7-酮基胆固醇)。结果:胆固醇在空气中易于氧化。随着加热时间的延长,未氧化胆固醇显著减少,所生成胆固醇氧化产物缓慢增加。脂肪酸(硬脂酸、油酸)中,在加热初期(30min)胆固醇氧化速度减缓,加热末期(120min)其氧化速度增加。食用油(猪油、玉米油)中,胆固醇在加热初期(30min)氧化速度显著减缓,在加热末期(120min)油脂的减缓作用不复存在。结论:胆固醇的高温氧化特性与所处媒介环境有关。     

甘油酯型n-3多不饱和脂肪酸富集方法研究进展北大核心CSCD

n-3多不饱和脂肪酸(n-3 PUFA)具有多种生理活性,其主要有3种存在形式,其中甘油酯型n-3 PUFA因其生物利用度高和不易被氧化而优于游离型和乙酯型。然而,目前鲜有对甘油酯型n-3 PUFA进行高纯度富集的方法。为了对甘油酯型n-3 PUFA的高值化更加深入的研究提供参考,综述了富集甘油酯型n-3 PUFA的3种常见方法(物理一步法、两步法和酶一步法)及优缺点。物理一步法可以避免产物氧化,但得率较低;两步法工艺复杂,并有可能产生环境污染;而酶一步法具有简单、高效等优点,成为学者们关注的焦点。现有脂肪酶对甘油酯型n-3 PUFA的富集能力有限,还需进一步发掘富集能力更强的选择性脂肪酶。     

蒸煮对不同品质鸭肥肝营养特性及脂肪酸组成的影响

研究3种不同品质的鸭肥肝在蒸煮后常规养分、脂肪酸组成及脂质过氧化的变化。结果表明:1)熟化增加了鸭肥肝中C12:0、总脂和丙二醛(MDA)的含量,降低了水分、蛋白的含量,对鸭肥肝中糖原的含量无影响;2)鱼油组肥肝熟化后,其SFA、PUFA、n-6PUFA、n-3PUFA、EPA、DHA均显著高于大豆油组肥肝(P<0.05),极显著高于玉米组肥肝(P<0.01);3)玉米组肥肝熟化后SFA和MUFA显著降低(P<0.05),PUFA、n-6 PUFA、n-3 PUFA显著升高(P<0.05),大豆油组肥肝熟化对这几种脂肪酸的影响不大,而鱼油组肥肝熟化后这几种脂肪酸含量均升高,其中n-6PUFA达到显著水平(P<0.05);4)熟化具有降低3种肥肝中EPA和DHA的趋势,EPA降低幅度以玉米组肥肝最大,DHA降低幅度以大豆油组肥肝最大。以上结果提示,鱼油组肥肝的食用价值最高。     

氧化反应中胆固醇与甘油酯相互作用

<正> 前言研究表明胆固醇和甘油酯的氧化产物对人体有害。最近采用新的色谱分析手段,能分离和鉴别出多种胆固醇的氧化产物,例如在煎炸的鸡肉中检测出6—53ppm胆固醇的环氧化物;在干燥的蛋黄粉中检测出7-羧基胆固醇(74ppm),7-酮     

鱼油精制过程中的品质变化规律及评价

在传统的鱼油生产中,毛油经脱胶、脱酸、脱色、脱臭等工艺可以得到品质合格的精制鱼油,但传统鱼油生产对胆固醇、胆酸、反式脂肪酸等关乎人体健康的成分关注较少。本文通过模拟传统的鱼油生产工艺,在确保成品鱼油品质合格的同时,对鱼油中DHA、EPA、胆固醇、总胆酸、反式脂肪酸(C18:1tran,C18:2trans,C18:3trans)等进行了分析。结果表明,成品鱼油的酸值(AV)、过氧化值(POV)、碘值(IV)分别为0.53 mg KOH/g,4.35 mmol/kg和139.60 g/100 g,均达到了多烯鱼油行业一级标准(SC/T 3502-2000)。精炼工艺对DHA和EPA的影响不大,DHA和EPA的相对总含量为26%左右。成品油中胆固醇和总胆酸含量随着精炼的进行呈下降趋势,成品油中含量分别为2399 mg/kg和30 mg/kg,脱除率分别为57.4%和97.2%。反式脂肪酸含量随着精炼的进行呈上升趋势,成品油中总反式脂肪酸的相对含量为1.42%。以上结果表明,传统的鱼油精炼工艺尚存在一定的缺陷,需及时改善工艺,进一步提高鱼油的品质。     

Cholesterol Oxidation in Fish and Fish Products

Fish and fish products are important from a nutritional point of view due to the presence of high biological value proteins and the high content of polyunsaturated fatty acids, especially those of the n‐3 series, and above all eicosapentaenoic acid and docosahexaenoic acid. However, these important food products also contain significant amounts of cholesterol. Although cholesterol participates in essential functions in the human body, it is unstable, especially in the presence of light, oxygen, radiation, and high temperatures that can cause the formation of cholesterol oxidation products or cholesterol oxides, which are prejudicial to human health. Fish processing involves high and low temperatures, as well as other methods for microbiological control, which increases shelf life and consequently added value; however, such processes favor the formation of cholesterol oxidation products. This review brings together data on the formation of cholesterol oxides during the preparation and processing of fish into food products which are recognized and recommended for their nutritional properties.     

Effect of total fasting on testicular lipid fractions in rats]

Rats weighing 290 g each were fasting for 12 days with no changes occurring in the weight of the testicles, total lipids, phospholipids, di- and triglycerides content therein. The cholesterol ethers level increased by 53 per cent and in the composition of di- and triglycerides and the cholesterol ethers the relative content of high-molecular polyunsaturated fatty acids was going up, while the fatty acids composition of the phospholipids remained the same.     

Metabolic fate of long-chain unsaturated fatty acids and their effects on palmitic acid metabolism and gluconeogenesis in bovine hepatocytes

The objectives were to determine the metabolic fate of different long-chain fatty acids, and their effects on palmitic acid metabolism and gluconeogenesis in bovine hepatocytes. Hepatocytes were isolated from four ruminating calves and exposed in suspension for 3 h to one of the following treatments: 1 mM palmitic acid (1C16), 2 mM palmitic acid (2C16), or 1 mM palmitic acid plus either 1 mM oleic (C18:1), linoleic (C18:2), linolenic (C18:3), eicosapentaenoic (C20:5), or docosahexaenoic acid (C22:6). Oxidation of [1-(14)C]palmitic acid or one of the [1-(14)C]-labeled treatment fatty acids to CO2 or incorporation into cellular triglycerides (TG), phospholipids, cholesterol, and cholesterol esters were measured. Rates of oxidation to CO2 were 3- to 4-fold higher for C22:6 than for other fatty acids, with the exception of C20:5, which had intermediate rates of oxidation to CO2. In general, treatments 2C16 and C18:1 yielded the highest rates of incorporation into most cellular lipids, whereas the polyunsaturated fatty acids were poor substrates for incorporation into cellular lipids. The most pronounced change was a large reduction of polyunsaturated fatty acid incorporation into cellular TG compared to 1C16, 2C16, and C18:1. The unsaturated fatty acids also influenced palmitic acid metabolism. The addition of C20:5 yielded the highest rates of palmitic acid oxidation to CO2 followed by addition of C18:1 and C22:6. Treatments containing polyunsaturated fatty acids decreased palmitic acid metabolism to TG and total cellular lipids compared with treatments 2C16 and C18:1. Rates of gluconeogenesis from propionate were significantly higher for the treatment containing C18:1. Long-chain fatty acids vary in their routes of metabolism and influence palmitic acid metabolism and gluconeogenesis in bovine hepatocytes.     

咸干鲅鱼自然风干过程中脂质变化

为探究咸干鲅鱼风干加工过程中脂质变化情况,以青岛传统咸干鲅鱼为研究对象,分别对鲜鱼和不同风干时间样品总脂含量、脂质组成、脂肪酸组成、酸价（acid value,AV）、过氧化值（peroxide value,POV）、硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARs）值进行检测。结果表明：鲜鲅鱼总脂含量为34.96 g/100 g（干基计）,在风干过程中变化不显著（P＞0.05）;与鲜鲅鱼相比,风干鲅鱼脂质组成发生明显变化,其中甘油三酯和磷脂的含量显著降低（P＜0.05）,而游离脂肪酸含量显著升高（P＜0.05）,胆固醇含量相对稳定。脂肪酸组成在加工过程总体变化较小,其中多不饱和脂肪酸相对含量在干制阶段有所减少。咸干鲅鱼风干加工过程中,POV、AV、TBARs值均呈上升趋势。咸干鲅鱼的风干加工过程会影响其脂质组分的相对含量,同时引起脂质的氧化分解。     

Milk triglycerides from dairy cows abomasally infused with increasing amounts of high-oleic sunflower fatty acids

The triglyceride composition of milk fat largely determines the manufacturing characteristics of products containing milk fat. Increasing oleic acid content of milk fat might be desirable for human nutrition and also for butter and whipping cream, among other product applications. The objective of this research was to determine the effects of increasing intestinally available oleic acid (provided via abomasal infusion) on the profile of milk triglycerides. A control and 4 increasing doses of free fatty acids from high oleic sunflower oil (HOSFA) were infused into the abomasum of 4 lactating dairy cows in a changeover experimental design with periods of 7 d. Treatments were (1) control (no fatty acids infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1,000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Infusion of HOSFA increased oleic acid and decreased short- and medium-chain fatty acids in milk fat. Statistical analysis of results showed linear changes in most of the milk triglycerides analyzed. The most significant changes as the result of increasing HOSFA infusion were a decrease in triglycerides with saturated fatty acids (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and an increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein. The synthesis of triglyceride is position-specific and does not follow a random distribution model.     

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.     

A CHOLESTEROL AND SUCROSE RICH DIET PROMOTES LIPOPROTEIN PEROXIDATION AND IMPAIRS INSULIN SENSITIVITY IN RATS

The effects of a diet rich in cholesterol and sucrose on lipoprotein peroxidation and insulin sensitivity were studied in rats. The protective role of fish oil dietary supplementation, both alone and associated with antioxidants, was also investigated. Four groups of 6 male rats were treated for 4 weeks with a standard diet, rich in cholesterol and sucrose (atherogenic diet), atherogenic diet plus fish oil and atherogenic diet plus fish oil enriched in polycosanols, terpenes and antioxidants. Atherogenic diet induced a significant increase in plasma concentration of cholesterol, triglycerides, free fatty acids and atherogenic index; moreover, it significantly enhanced the susceptibility of lipoproteins to peroxidation and the resistance to insulin. Dietary integration with fish oil limited the development of the above risk factors, the association with polycosanols, terpenes and antioxidants being more efficacious than fish oil alone.     

A comparison of the physico‐chemical properties of low‐cholesterol ghee with standard ghee from cow and buffalo creams

Low‐cholesterol ghee with 90% less cholesterol was prepared using β‐cyclodextrin. The physico‐chemical properties such as Reichert‐Meissl (RM) value, Polenske value, Butyro‐refractometer (BR) reading at 40°C, Iodine value and free fatty acids (FFA) as oleic acid in cow standard ghee and the corresponding low‐cholesterol ghee remained almost unaltered. A similar trend was also observed in buffalo ghee. Fat soluble vitamins (β‐carotene, A and E) in both cow and buffalo low‐cholesterol ghee were very similar to that of respective standard ghee samples. However, 65 to 70% loss of vitamin D was observed in low‐cholesterol ghee.     

Lipid and antioxidant blood levels in vegetarians

Parameters of lipid metabolism (triacylglycerols TG, cholesterol CH, HDL-CH, LDL-CH, atherogenic index AI, profile of fatty acids) were measured in blood samples of 81 healthy lacto and lacto-ovo vegetarians (42 males, 39 females; age range 19–39 years). The average period of being on a vegetarian diet was 6.2 years. Low levels of TG, CH, LDL-CH, AI and HDL-CH values on the borderline between standard and reduced risk (1.4 mmol middot; 1^?1) can be considered as favourable from the atherosclerosis prevention aspect. Compared with non-vegetarians (n = 62), the levels of TG, CH, LDL—CH, and AI are significantly reduced in the vegetarian group. As opposed to non-vegetarians, vegetarians showed a higher total sum of polyunsaturated fatty acids, a significantly higher content of linoleic acid (C 18:2) and linolenic acid (C 18:3), unchanged content of oleic acid (C 18:1), stearic acid (C 18:0) and other polyunsaturated fatty acids. The process of lipoperoxidation (with polyunsaturated fatty acids as substrate) is involved in the etiology of cardiovascular and oncological diseases. Favourable values of prooxidative-antioxidative parameters demonstrated a reduced risk of lipoperoxidation in vegetarians, compared to non-vegetarians (significantly reduced content of conjugated dienes of fatty acids in plasma, significantly higher plasma levels of vitamin C, β-carotene, vitamin E/cholesterol ratio — an indicator of LDL protection, vitamin E/triacylglycerols ratio — an indicator of fatty acid protection —, selenium and glutathione-peroxidase activity).