肉中L-肉碱的提取及含量比较研究

L-肉碱在生物体内的长链脂肪酸运送到线粒体过程中起重要的作用.各种肉中都有不同含量的L-肉碱,本文采取三种不同溶剂提取,并用酶法和高效液相色谱法进行检测,而对于L-肉碱的定量,高效液相色谱法是较为实用和精确的方法.比较各种肉中肉碱的含量及所在肉的品种羊肉、牛肉、猪肉和鸡肉.结果显示,羊肉含有最高含量的L-肉碱,鸡肉最少,几乎不能被检测出.L-肉碱的最佳提取率可通过高氯酸达到,但考虑到实用性问题,用盐酸作为提取溶剂,也能得到较好的提取效果.     

产L-肉碱微生物及发酵法生产L-肉碱研究概况

本文介绍了产Ｌ－肉碱的微生物和发酵法生产Ｌ－肉碱概况。其生产方法包括固态发酵法和液态发酵法。并对不同种类的微生物、不同工艺生产Ｌ－肉碱的情况展开了讨论。     

L-肉碱对肉鸡腹脂沉积的影响及作用机理探讨

选用 4 80羽 1日龄Avain肉鸡 ,随机分成 4个处理组 ,分别饲喂添加 0、2 5、5 0、75 (mg/kg)L -肉碱的试验饲粮 4 9d ,研究L -肉碱对肉鸡腹脂沉积的影响及其作用机理。结果表明 :不同水平L -肉碱对肝重比率和肝脂含量均无明显影响 (P >0 .0 5 ) ,但添加 5 0mg/kg和 75mg/kgL -肉碱均显著地降低了肉鸡腹脂重比率(P <0 .0 5 )。添加 5 0mg/kg和 75mg/kgL -肉碱使腹脂中激素敏感脂酶的总活力增强 (P <0 .0 3) ,苹果酸脱氢酶的总活力降低 (P <0 .0 5 ) ;使胸肌中总肉碱含量 (P <0 .0 5 )、酸不溶肉碱含量 (P <0 .0 1)及其与游离肉碱含量的比值 (P <0 .0 3)增高 ;使血清中总肉碱 (P <0 .0 1)、游离脂肪酸 (P <0 .0 1)和肌酸酐浓度 (P <0 .0 3)提高 ,甘油三酯浓度降低 (P <0 .0 5 )。上述结果提示 :L -肉碱通过改变鸡体内脂肪代谢相关酶的活力 ,促进脂肪酸的氧化利用 ,而产生降低腹脂沉积的效果     

食物中L-肉碱含量及其测定方法的研究进展

L-肉碱即左旋肉碱,是促进脂肪转化为能量的必需营养素,它具有调节脂代谢、提高抗氧化和免疫能力等功能,对于人类的健康和疾病预防具有重要的作用。本文在概述L-肉碱生理功能的基础上,对食物中L-肉碱含量及L-肉碱测定方法进行系统综述,为正确认识L-肉碱、科学合理地利用食物中L-肉碱资源提供基础理论依据,为获得一种简单、快速、准确、特异性强的L-肉碱测定方法并应用于实践提供参考数据。     

L-肉碱的生物学制备及相关研究

L-肉碱是存在于动物组织、植物和微生物中的一种类似维生素的营养物质,在临床、保健等行业有着广泛的应用。本文从理化性质、功能、应用和制备的角度,综述了L-肉碱的相关研究进展,为其大规模的制备提供了理论参考。     

L-肉碱的合成及在食品工业中的应用

L 肉碱是重要的功能因子 ,在哺乳动物长链脂肪酸代谢等方面起着关键作用 ,在医药、食品和饲料工业等方面的应用愈发广泛。本文综述了L 肉碱的合成研究进展 ,并简要叙述了L 肉碱在食品工业的应用。     

高效液相色谱法测定鸡血浆中L-肉碱含量

试验旨在建立高效液相色谱（high-performance liquid chromatography,HPLC）法检测鸡血浆中L-肉碱含量的方法。样品采用乙腈甲醇混合液（9∶1,体积比）提取,涡旋振荡,离心,定容后,经0.22 μm 滤膜过滤,使用ACE Excel 5 Super C18 色谱柱进行分离。流动相为乙腈-5 mmol/L 庚烷磺酸钠（加入0.1%磷酸）水溶液（15∶85,体积比）,流速0.6 mL/min,柱温30 ℃,检测波长210 nm,进样量20 μL。结果显示,该条件下,L-肉碱质量浓度与其峰面积在0.01～0.60 mg/mL 内,具有良好的线性关系,相关系数为0.999 8,检测限为0.005 mg/mL,定量限为0.017 mg/mL,平均回收率为97.393%～98.703%,相对标准偏差（relative standard deviation,RSD）为0.8%（n=6）。使用该方法测得鸡血浆中L-肉碱峰型良好,无杂峰干扰。研究表明该方法成本低,操作简单,有较高的回收率,适用于鸡血浆中L-肉碱的含量测定。     

羊肉中L-肉碱抗疲劳作用的研究

研究羊肉中L-肉碱抗疲劳作用.将昆明种小鼠分组,分别用平行实验和交叉实验测定抗疲劳功能,观察L-肉碱对实验小鼠游泳时间、身体指数、血清生理生化指标和腿部肌肉L-肉碱含量的影响.L-肉碱可以有效延长实验小鼠平均游泳时间,减轻体重及腹部脂肪量,显著降低血清中甘油三酯及总胆固醇的水平、乳酸及尿素氮含量;液相色谱显示小鼠体内L-肉碱含量与游泳时间有显著的相关性.L-肉碱有显著的抗疲劳作用.     

L-肉碱的研究现状及其应用

本文综述了新型营养物质-L-肉碱的性质、作用机制、生产方法及其在食品、医学等领域的最新应用进展。     

产L-肉碱的大肠杆菌基因工程改造及生物转化

L-肉碱在脂肪代谢中起重要的作用,本文构建了T7启动子控制下的过表达质粒p ET28a-cai BCD和p ACYCD-cai F-cai T,并将其转入大肠杆菌BL21（DE3）（简写DE3）中,得到基因工程菌BL21（DE3）/cai BCD+cai F+cai T（简写DE3/BCD+F+T）。将此菌株接种到生长培养基中,并用终浓度为1 mmol/L的IPTG（异丙基硫代半乳糖苷）诱导培养,然后收集菌体细胞加入到含有巴豆甜菜碱盐酸盐的转化液中进行转化。结果显示,IPTG诱导4 h比诱导10 h后转化得到的L-肉碱量要高,转入了过表达质粒的工程菌DE3/BCD+F+T（7.244 g/L）比野生型DE3（0.5 g/L）提高了15倍。该巴豆甜菜碱盐酸盐转化生成L-肉碱的反应在2 h后基本达到稳定。      

牛磺酸对肥胖大鼠甘油三酯和胆固醇代谢的影响

目的 探讨长期经饮水方式补充牛磺酸对高脂膳食所致肥胖大鼠降脂减重作用,对甘油三酯合成关键分子和胆固醇7α羟化酶(cholesterol 7α-hydroxylase, CYP7A1)表达调控关键分子的影响。方法 根据血清胆固醇水平和体重, SD大鼠被分为3组,为对照组(normal, N)饲喂基础维持饲料,肥胖组(high fat, HF)和牛磺酸组(high fat taurine, HFT)饲喂高脂饲料。N组和HF组自由饮水,而HFT组给予牛磺酸溶液代替水,持续12周。结果 与HF组相比,给予牛磺酸的HFT组大鼠体重、附睾周围脂肪重量、血清总胆固醇和低密度脂蛋白胆固醇、游离脂肪酸、固醇调节元件结合蛋白-1c (sterol regulatory element-binding protein-1c, SREBP-1c)和脂肪酸合成酶(fatty acid synthase, FAS)基因表达显著降低,粪便胆汁酸水平、脂蛋白脂肪酶(lipoprotein lipase, LPL)活性以及CYP7A1和Ser63p-c-Jun的蛋白表达显著增加,但肝细胞核因子4α(hepatocyte...     

樟树籽仁油对高脂诱导型肥胖小鼠体脂和血脂水平的影响

采用不同樟树籽仁油(CCSKO)含量的高脂饲料干预营养型肥胖小鼠,研究高脂饲料中樟树籽仁油的含量对樟树籽仁油降低营养型肥胖小鼠体脂和血脂效果的影响。正常C57BL/6小鼠饲喂基础饲料作为正常对照组(NC组),同时采用高脂饲料诱发C57BL/6小鼠产生营养型肥胖。将肥胖小鼠随机分为基础饲料恢复组(NR组)、高脂猪油组(HF组)、含21. 91%CCSKO(CCSKO替换25%猪油)的高脂饲料组(HF-25%CCSKO组)、含43. 83%CCSKO(CCSKO替换50%猪油)的高脂饲料组(HF-50%CCSKO组)、含87. 66%CCSKO(CCSKO替换100%猪油)的高脂饲料组(HF-100%CCSKO组),连续喂养10周,测定小鼠体重、体长、腹部脂肪质量及血清相关生化指标,分析肝脏组织切片。结果表明:HF-50%CCSKO组、HF-100%CCSKO组的体重、腹部脂肪质量和血清ALT、AST水平比HF组显著降低,HF-100%CCSKO组的TC、LDL-C、LDL-C/HDL-C水平比HF组显著降低。HF-50%CCSKO组的TC、LDL-C、LDL-C/HDL-C水平与HF组相...     

不同粒径毛木耳粉对高脂诱导肥胖大鼠的作用研究

目的:比较不同目数毛木耳粉对高脂性营养饮食诱发性肥胖大鼠的减肥降脂功效。方法:利用高脂营养饲料诱发SD大鼠肥胖模型的同时,给予不同目数毛木耳粉混悬液,观察摄食量、动物体重的变化,检测动物血脂水平,计算脂体比。结果:在各组食物利用率无显著性差异情况下,100~200、200~300、300~400目和400目以上毛木耳粉组大鼠体重均低于模型对照组,从第4周开始有显著性差异(p<0.05或p<0.01);100~200、200~300、300~400目和400目以上毛木耳粉组体重增加量比模型对照组显著性降低(p<0.05或p<0.01),同时,400目以上毛木耳粉组大鼠的脂重、脂体比和低密度脂蛋白均明显低于模型对照组(p<0.05)。结论:100~200、200~300、300~400目和400目以上毛木耳粉有预防性减肥作用,其中300~400目和400目以上毛木耳粉的效果更显著。此外,400目以上毛木耳粉还有降脂功效。      

不同粒径毛木耳粉对高脂诱导肥胖大鼠的作用研究

目的:比较不同目数毛木耳粉对高脂性营养饮食诱发性肥胖大鼠的减肥降脂功效。方法:利用高脂营养饲料诱发SD大鼠肥胖模型的同时,给予不同目数毛木耳粉混悬液,观察摄食量、动物体重的变化,检测动物血脂水平,计算脂体比。结果:在各组食物利用率无显著性差异情况下,100~200、200~300、300~400目和400目以上毛木耳粉组大鼠体重均低于模型对照组,从第4周开始有显著性差异(p0.05或p0.01);100~200、200~300、300~400目和400目以上毛木耳粉组体重增加量比模型对照组显著性降低(p0.05或p0.01),同时,400目以上毛木耳粉组大鼠的脂重、脂体比和低密度脂蛋白均明显低于模型对照组(p0.05)。结论:100~200、200~300、300~400目和400目以上毛木耳粉有预防性减肥作用,其中300~400目和400目以上毛木耳粉的效果更显著。此外,400目以上毛木耳粉还有降脂功效。     

Effect of increasing the protein-to-fat ratio and reducing fat content on the chemical and physical properties of processed cheese product

Scientific studies indicate that the intake of dietary fat and saturated fats in the modern Western diet is excessive and contributes adversely to health, lifestyle, and longevity. In response, manufacturers of cheese and processed cheese products (PCP) are pursuing the development of products with reduced fat contents. The present study investigated the effect of altering the fat level (13.8, 18.2, 22.7, 27.9, and 32.5 g/100 g) in PCP on their chemical and physical properties. The PCP were formulated in triplicate to different fat levels using Cheddar cheese, skim milk cheese, anhydrous milk fat, emulsifying salt (ES), NaCl, and water. The formulations were designed to give fixed moisture (~53 g/100 g) and ES:protein ratio (0.105). The resultant PCP, and their water-soluble extracts (WSE), prepared from a macerated blend of PCP and water at a weight ratio of 1:2, were analyzed at 4 d. Reducing the fat content significantly increased the firmness of the unheated PCP and reduced the flowability and maximum loss tangent (fluidity) of the melted PCP. These changes coincided with increases in the levels of total protein, water-soluble protein, water-insoluble protein, and water-soluble Ca, and a decrease in the molar ratio of water-soluble Ca to soluble P. However, both water-soluble Ca and water-soluble protein decreased when expressed as percentages of total protein and total Ca, respectively, in the PCP. The high level of protein was a major factor contributing to the deterioration in physical properties as the fat content of PCP was reduced. Diluting the protein content or reducing the potential of the protein to aggregate, and thereby form structures that contribute to rigidity, may provide a means for improving quality of reduced-fat PCP by using natural cheese with lower intact casein content and lower calcium:casein ratio, for example, or by decreasing the ratio of sodium phosphate to sodium citrate-based ES.     

Antiobesity and lipid lowering effects of theaflavins on high-fat diet induced obese rats

Theaflavins are major polyphenols in black tea. This study investigated antiobesity and lipid lowering effects of black tea extract (BTE), a highly purified theaflavins mixture (TFs, 83.84%) and theaflavin (TF1, 93.25%) on high-fat diet (HFD) induced obese rats. The body weight was slightly reduced by BTE and TFs (p > 0.05), and was significantly decreased by TF1 (p < 0.05) relative to the HFD control group. All samples remarkably decreased the food intake, adiposity index and the serum levels of total cholesterol (TC), triacylglycerol (TG) and low-density lipoprotein cholesterol (LDL-C) (p < 0.05), except that BTE and TF1 insignificantly decreased the TC concentration (p > 0.05). Moreover, administration of BTE, TFs and TF1 all significantly decreased atherogenic index (AI), enhanced insulin sensitive index (ISI), inhibited the hepatic lipase (HL) activity (p < 0.05), and slightly reduced leptin level in liver, decreased serum alanine transaminase (ALT) activity and increased serum superoxide dismutase (SOD) activity (p > 0.05) as compared to that of the HFD controls. These results indicated that theaflavins were one of the functional components which contributed to the antiobesity and lipid lowering effects of black tea, and might reduce the risk of type 2 diabetes and cardiovascular disease (CVD) in obese patients.     

The importance of GLP‐1 and PYY in resistant starch's effect on body fat in mice

Resistant starch (RS) is a dietary fermentable fiber that decreases body fat accumulation, and stimulates the secretion of glucagon‐like peptide‐1 (GLP‐1) and peptide YY (PYY) in rodents. GLP‐1 and PYY are gut‐secreted hormones with antiobesity effect. Thus, blocking the signals of increased GLP‐1 and PYY may also block the effect of dietary RS on body fat. In a 10‐week study, C57BL/6J and GLP‐1 receptor null (GLP‐1R KO) mice were fed control or 30% RS diet, and received daily intraperitoneal injection of either saline or PYY receptor antagonist (BIIE0246, 20 μg/kg body weight). Dietary RS significantly decreased body fat accumulation only in wild‐type mice that has saline injection, but not in GLP‐1R KO mice. PYY receptor antagonist diminished RS action on body fat in wild‐type mice, but did not interfere with GLP‐1R KO mice response to RS. Regardless of genotype and injection received, all RS‐fed mice had increased cumulative food intake, cecal fermentation, and mRNA expression of proglucagon and PYY. Thus, our results suggest that increased GLP‐1 and PYY is important in RS effects on body fat accumulation.