Thermal Stability of Folic Acid and 5-Methyltetrahydrofolic Acid in Liquid Model Food Systems

The effects of temperature, iron and ascorbate fortification, and oxygen concentration on the stabilities of folic acid (FA) and 5- methyltetrahydrofolic acid (5-CH₃-THF) were examined in liquid model food systems. Small retort pouches were used as reaction vessels and the model systems were processed at 100°C, 120°C, and 140°C. A cation-exchange procedure was devised to provide sample extract purification before quantitation using high-performance liquid chromatography (HPLC). FA and S-CH₃-THF were found to be very stable under these conditions. Lactose, protein, iron and ascorbate were all found to be capable of reducing the oxygen partial pressure within the model systems, thereby enhancing the stability of FA and 5-CH₃-THF. FA and 5-CH₃-THF degradation was not zero or first order but possibly second order as a result of limiting oxygen concentrations.     

Thermal Destruction of 5-Methyltetrahydrofolic Acid in Buffer and Model Food Systems

Thermal kinetic data (rate constants, k, and activation energies, Ea) for 5-Methyltetrahydrofolic acid (5-CH₃-H₄PteGlu) were determined in citrate buffers (pH 3-6) and in model food systems between 100° and 140°C. As pH increased from 3.0 to 6.0, the rate constants decreased as the temperature increased from 100° to 130°C, the rate constants increased. Ea values were 19.0, 17.0, 19.7 and 19.8 kcal/mole at pH 3, 4, 5 and 6, respectively. In the model food systems, the Ea values (kcal/mole) were 7.85 in apple juice and 10.6 in tomato juice. When dissolved oxygen content was reduced to 5.3 ppm, the stability of the 5-CH₃H₄PteGlu was increased substantially.     

核酸营养研究新进展

饮食核酸是一种条件型必需营养素,参与并影响生物合成的过程,能促进免疫细胞生长和免疫细胞因子分泌,介导炎症应答稳定代谢内环境,促进肠胃系统发育,维持肠道菌群平衡,直接影响基因表达,影响脂质、葡萄糖代谢,延缓衰老脑形态改变及记忆障碍的发生,减少DNA的氧化损伤,保护和修复损伤的DNA。补充饮食核酸对细胞营养、抵御衰老、预防疾病具有广泛而且稳定的营养保健作用。     

Nutritional Evaluation of Breadfruit-containing Composite Flour Products

Composite flours containing wheat, breadfruit flour and soy protein, whey or peanut meal were formulated and incorporated into western style bread and biscuits. Bread containing 10% breadfruit flour and 5% whey, and biscuits containing 10% breadfruit flour and 5% soy protein were judged most acceptable in flavor, color, and texture. Breadfruit flour contained 4.4% protein and was lower in sulfur containing amino acids and higher in lysine than wheat flour. Breadfruit containing bread and biscuits had low amino acid scores. The protein efficiency ratio (PER) of the biscuit product, however, was similar to that of the casein control while the PER of bread was significantly lower. Results suggest that acceptable products can be made with composite flours containing 10% breadfruit flour.     

从罗氏维生素到帝斯曼营养产品

凭借其发展远见,拥抱变化的意愿,强大的创新能力,对客户需求变化的敏感,以及在社会上的深厚基础,一个世纪以来,帝斯曼集团(DSM)的业务经历了许多变化-从采煤转变为天然气化工产品,后转为石油化工产品,进而转为专业化学品,到现在发展生物技术产品.帝斯曼集团2005年的远景战略是致力专注于以更快增长和更稳定利润水平,在更高附加值的业务领域建立全球领导地位.     

从罗氏维生素到帝斯曼营养产品

<正> 凭借其发展远见,拥抱变化的意愿,强大的创新能力,对客户需求变化的敏感,以及在社会上的深厚基础,一个世纪以来,帝斯曼集团的业务经历了许多变化-从采煤转变为天然气化工产品,又转为石油化工产品,进而转为专业化产品,到现在发展生物技术产品。在全球范围内,帝斯曼集团正活跃于生命科学、性能材料和工业化工领域,公司的创新产品和创新服务不断帮助人们改善着生活质量。帝斯曼的产品被广泛地应用于终端市场,例如人类和动物营养保健领域、化妆品业、制药业、汽车业、运输业、涂料业、建筑业和电动机械行业。     

牛奶及其制品的营养特性

牛奶是一种营养成分齐全、组成适宜、易消化吸收的天然优质食品。不但适合于婴儿、病人及老年人,也适合于广大的普通人群。牛奶含有丰富的优质蛋白质,平均含蛋白质3%(占总乳固形物的27%),生物价(BV)为87,氨基酸评分(AAS)为0.98;含脂肪≥3%(占总乳固形物≥27%),其中油酸占30%,亚油酸5.3%,亚麻酸2.1%,同时,还含有较高的短链脂肪酸;含乳糖约3.4%(占总乳固形物31%),乳糖具有促进钙吸收,促进肠道有益菌繁殖,抑制腐败菌生长的作用;含钙约1l0mg/100g,且吸收率高;此外还含有丰富的维生素。对于现在的中国膳食结构而言,牛奶类食品的主要作用是提供…     

Nutritional Evaluation of the Protein in Oilseed Products Heated with Sugars

Defatted flours and protein isolates from glandless cottonseed, peanut, and soybean were complexed with glucose or sucrose in a ratio of 1:1 by weight and heated at 100°C for 0, 2, or 6 hr. Quality changes by the heat treatment were assessed by determining the extent of browning (browning index), in-vitro protein digestibility, available lysine total amino acids, and computed protein efficiency ratio (C-PER). Whereas the sucrose-containing complexes changed very little in all the quality parameters determined, the counterparts containing glucose decreased substantially in protein quality along with the increased intensity of browning. Before heating, protein digestibility of the complex containing defatted flour of an oilseed was lower than that of the isolate counterpart. When heated, however, the isolate-glucose complexes decreased more in protein digestibility than the flour-glucose complexes. The available lysine content decreased by 76-83% for the complexes with glucose in contrast with 2-10% for those with sucrose. As to total amino acids, marked losses in arginine, lysine, tryptophan, and histidine were found in the complexes containing glucose, with the arginine loss as high as the lysine loss. Lysine-rich soy proteins lost lysine in greater percentages than lysine-poor peanut and cottonseed proteins. C-PER decreased by 63-86% in the glucose-containing complexes, with the highest decrease shown for soy flour-glucose. In-vitro protein digestibility, available lysine, and C-PER were all highly correlated (P < 0.01) with browning index. Available lysine was also highly correlated with C-PER.     

不同来源鱼鳔的营养成分比较分析

鱼鳔、鲍鱼、海参及鱼翅统称为“海四珍”,是传统的珍贵食材。市场上鱼鳔的种类众多,然而有关不同来源鱼鳔营养成分的研究报道较少。该研究从传统食用的鲈形目鱼鳔及新资源鳕形目鱼鳔中挑选了几个代表性品种,比较其营养成分差异。结果发现：7种鱼鳔都是高蛋白、低脂肪食品。甘氨酸、谷氨酸、丙氨酸、脯氨酸、精氨酸和羟脯氨酸是鱼鳔的主要氨基酸,赤嘴鱼、石首鳘鱼、黄花鱼、石斑鱼、新西兰鳕鱼、冰岛鳕鱼和红鱼的鱼鳔主要氨基酸分别占总氨基酸的 73.81%、70.04%、70.22%、67.15%、66.50%、65.50%、62.63%,功能性氨基酸（functional amino acid,FAA）∶总氨基酸（total amino acid,TAA）约为0.70。不同来源鱼鳔的锌、硒含量差异较大,红鱼鳔的锌含量低于检测限,黄花鱼鳔则高达 4.56 mg/100 g。硒含量为 19.00 μg/100 g～77.00 μg/100 g。     

3 种方法提取燕麦麸蛋白及其产物的比较

通过单因素和正交试验优化碱法、超声辅助碱法及超声辅助酶碱法提取燕麦蛋白的工艺。结果表明：在最佳条件下燕麦蛋白的提取率分别可达31.96%、39.31%、61.43%;根据燕麦蛋白在不同pH 值条件下的溶解性及沉淀率,确定碱法、超声辅助碱法和超声辅助酶碱法所提燕麦蛋白的等电点分别为4.6、3.6、3.8,沉淀率分别为57.92%、63.24%、72.24%;通过氨基酸组成分析和营养价值的评定,可知3 种提取方法所提取的燕麦蛋白符合FAO/WHO 推荐的模式,超声辅助酶碱法所提取的燕麦蛋白的必需氨基酸指数(EAAI)较其他两种方法的高,说明其营养价值较高。     

大麦苗粉营养成分及其制品研究进展

大麦苗粉富含蛋白质、维生素、矿物质、叶绿素、黄酮类、γ-氨基丁酸等营养性成分,对大麦苗粉的营养性成分及其制品的研究现状进行了综述,为开发含大麦苗粉相关产品提供一定的参考。     

斑点叉尾触鱼鱼皮及其制品的营养品质比较

研究班点叉尾鲴鲜鱼皮及经过加工后的鱼皮的营养成分,结果表明,鲜鱼皮、加工后鱼皮的水分分别为65．41％、85．43％;蛋白质分别为21．32％、13．74％;脂肪分别为12．38％、1．25％;必需氨基酸总量与氨基酸总量之比分别为22．63％、20．74％;鲜味氨基酸总量与氨基酸总量之比分别为65．77％、68．39％;胶原蛋白与粗蛋白之比分别为81．05％、90．97％。     

新疆巴旦姆种仁高级脂肪酸与氨基酸营养评价

以新疆巴旦姆28个品种为试验材料,采用超临界CO2萃取法萃取其种仁油脂。用气相色谱法测定脂肪酸的含量及组分;采用自动定氮法和连续累进提取法测定粗蛋白和分离蛋白,并对蛋白质和氨基酸进行了营养的分析。结果表明,巴旦姆种仁油脂含量高(平均为54.68%),油脂以不饱和脂肪酸为主要成分,平均占脂肪酸总量的92.3%(其中单不饱和脂肪酸平均占脂肪酸总量的72.19%),饱和脂肪酸含量较低。巴旦姆种仁粗蛋白质含量平均为22.55%,以清蛋白为主,平均占蛋白质总量的48.86%以上,其次为球蛋白,而醇溶蛋白和谷蛋白含量较低。其蛋白质均含18种氨酸酸,属完全蛋白质。氨基酸含量丰富,每百克蛋白质中18种氨基酸平均含量为92.5%,且富含人体所需的8种必需氨基酸,含量达27.5%～35.1%。谷氨酸含量最高(平均为21.0%),含硫氨基酸(Met Cys)和赖氨酸(Lys)为其限制氨基酸。     

东方伊萨酵母羧酸转运蛋白基因的表达及功能验证

生物降酸是现代果酒绿色酿造的重要发展方向,目前关于部分羧酸转运蛋白及其转运调控机制仍不完整,严重限制了高效降酸菌株的定向选育。本试验以1株自主筛选的具有良好降酸能力的东方伊萨酵母GS1-1为材料,对其羧酸转运蛋白基因进行表达及功能验证。首先,利用NCBI上已有东方伊萨酵母基因组序列与被证明为不同羧酸转运蛋白的编码基因进行BLAST比对,获得5条候选羧酸转运蛋白基因,利用生物信息学进行基因比对、跨膜螺旋预测、构建系统进化树,并采用绿色荧光蛋白定位。构建单倍体酿酒酵母BY4741 ADY2、JEN1羧酸转运蛋白双缺失工程菌,将含候选片段的质粒在酿酒酵母中进行表型验证及特异性验证,发现目的片段4(OUT23260.1)为苹果酸羧酸转运蛋白,目的片段1(XP_029319440.1)是柠檬酸转运蛋白,目的片段发挥功能区域定位于酵母细胞膜上。本研究为探索发酵工程领域中非酿酒酵母降酸机理提供参考。     

牦牛乳制品中马尿酸和苯甲酸含量快速检测方法

利用高效液相色谱建立一种同时检测马尿酸和苯甲酸的快速检测方法,对不同沉淀剂、流动相、流速、回收率、最低检出限等进行讨论研究。结果表明:在C18(250 mm×4.6 mm,5.0μm)为分离柱,检测波长为230 nm,进液量为20μL条件下,流动相为甲醇-0.4%乙酸水溶液(50∶50,体积比),流速为0.9 mL/min时,马尿酸、苯甲酸在1μg/mL～100μg/mL范围内线性良好,最低检测浓度为0.038μg/mL,马尿酸平均回收率为96.79%～98.10%,相对标准偏差(relative standard deviation,RSD)为0.58%～1.07%,苯甲酸平均回收率为93.54%～98.99%,RSD为0.71%～1.19%。该方法灵敏度高、重现性好,定性定量分析效果佳。     

复合发酵棉籽粕营养价值及活性产物分析研究

旨在研究复合固态发酵(两株酵母和一株霉菌)对棉籽粕脱毒效果及营养价值的影响,同时分析测定发酵底物中的活性产物。结果表明:复合发酵可极显著降低棉籽粕底物游离棉酚含量(P0.01),降解率达71.90%;棉籽粕底物粗蛋白、总氨基酸和必需氨基酸含量分别提高28.96%、8.83%、7.58%;发酵54~60 h时底物中蛋白酶活力最高(酸性蛋白酶活力为931.58 U/g,中性蛋白酶活力为1 097.79 U/g,碱性蛋白酶活力为798.62 U/g),纤维素酶活力最高(滤纸酶活力为1 601.66 U/g,Cx酶活力为3 590.02 U/g,C1酶活力为1 685.35 U/g),淀粉酶活力最高为578.05 U/g;同时发酵过程产生了一定量的有机酸。     

乳制品中马尿酸HPLC的测定

建立一种高效液相色谱法(HPLC)同时测定乳制品中马尿酸和苯甲酸含量的方法。在选定的实验条件下,马尿酸和苯甲酸的线性相关系数分别为0.999 0和0.999 8,测定低限分别为0.326 mg/kg和0.351 mg/kg,回收率分别在86.085%~101.948%和86.943%~100.533%,相对标准偏差(RSD)均小于2%。该方法具有良好的准确度、精密度和较高的重现性,对控制、解决乳制品的安全卫生问题具有重要意义。     

帝斯曼营养产品部牵手复旦大学强强联合打造世界一流实验室

全球食品、饲料和化妆品行业中领先的维生素及胡萝卜素供应商帝斯曼营养产品部与复旦大学于2004年12月共同宣布,双方将在营养和健康研究领域建立起长期的合作关系,并签署了一项投资额高达约3600万元人民币(500万瑞士法郎)的合作协议.根据这一协议,双方将在复旦大学设立一个可供约20名科学家开展科研工作联合实验室,并在未来展开多种合作.     

桑叶蛋白氨基酸组成分析及营养价值评价

在对桑叶蛋白氨基酸含量及其组成进行分析的基础上,应用模糊识别法和氨基酸比值系数法,以联合国粮食及农业组织推荐的全鸡蛋蛋白为标准蛋白,以联合国粮食及农业组织/世界卫生组织氨基酸模式为评价标准,对桑叶蛋白的营养价值进行了全面评价,并与其他4 种食物蛋白进行对照比较。结果表明：桑叶蛋白氨基酸种类丰富,至少含有17 种氨基酸,必需氨基酸占总氨基酸的34.7%左右,第一限制氨基酸为异亮氨酸。通过氨基酸比值系数法评价,桑叶蛋白的氨基酸比值系数分为69.71,是一种营养价值较高的蛋白质。