某蛋白质粉的营养价值评价

目的了解某蛋白质粉的蛋白质营养价值。方法采用化学和生物学方法测定和分析某蛋白质粉的营养价值,并与酪蛋白进行比较。根据国标测定蛋白质粉的化学成分。单笼饲养50～70g的SPF级初断乳Wistar大鼠36只,适应环境后根据体重随机分为3组,分别为无氮组以及含蛋白质10.4%的酪蛋白组和含蛋白质10.5%的蛋白质粉组。按照AOAC（美国官方分析化学师协会）标准给予饲料,根据食物摄入量、体重增加量和饲料中的蛋白质含量计算出蛋白质功效比值（PER）。使用代谢笼,单笼饲养180 g左右的SPF级幼年Wistar大鼠12只,分为无氮组和蛋白质粉组,每天收集每只大鼠的粪便和尿液,测定其中的蛋白质含量,计算出表观消化率（AD）和真消化率（TD）。结果化学方法得出受试蛋白质粉的必需氨基酸（EAA）占其氨基酸总量的41.74%,EAA组成与FAO/WHO模式接近,支链氨基酸（BCAA）含量约占氨基酸总量的20%,蛋白质的氨基酸评分（AAS）、化学评分（CS）为69.1、59.8。生物学方法得出受试蛋白质粉的PER为2.22,蛋白质粉组大鼠的食物利用率（32.93%）与酪蛋白组（33.01%）比较,差异无统计学意义（P〉0.05）。受试蛋白质粉的AD和TD分别为93.90%和94.27%,生物价（BV）为90.45,蛋白质净利用率（NPU）为85.34%。结论受试蛋白质粉的EAA和BCAA含量较高,生长价值与酪蛋白类似,受试蛋白质粉的氨基酸评分、消化率、生物价、蛋白质净利用率等评价指标均高于大豆蛋白,与鱼肉、牛肉等动物性食品的蛋白质营养价值接近,说明受试蛋白质粉的蛋白质营养价值高,是良好的蛋白质来源。     

大豆平衡氨基酸营养价值的研究

大豆平衡氨基酸是水解大豆蛋白后,添加蛋氨酸和色氨酸制成的一种氨基酸组成比较平衡的氨基酸混合物,其必需氨基酸含量达46.5％(含胱氨酸和酪氨酸);第1限制氨基酸为蛋氨酸+胱氨酸,氨基酸分(AAS)为0.97,化学分(CS)为0.55,必需氨基酸指数(EAAI)为91.53,均较酪蛋白高。动物试验表明,大豆平衡氨基酸可促进幼年大鼠生长;蛋白质功效比值(PER)达3.38±0.23,净蛋白质比率(NPR)达4.65±0.34,真消化率(TD)达96.44±102,生物价值(BV)达77.06±1.41,净蛋白质利用率(NPU)达74.14±0.89,与酪蛋白组比较,除消化率与酪蛋白一致外,其余各项指标均显著高于酪蛋白组,研究结果提示,大豆平衡氨基酸是“要素膳”的理想氮源。     

强化大豆高支氨基酸营养价值及其治疗实验性烫伤的研究

强化大豆高支氨基酸是采用特殊工艺水解大豆蛋白,并添加个别氨基酸,制成的氨基酸混合物。必需氨基酸含量高达68.89％,支链氨基酸占42.85％。动物试验表明,可促进幼年大鼠生长,蛋白质功效比值(PER)、真消化率(TD)、生物价(BV)、净蛋白利用率各为2.78、94.02％、85.0、79.99％,明显优于酪蛋白,亦优于大豆平衡氨基酸。动物烫伤实验治疗表明,能改善烫伤的负氮平衡(高支氨基酸组、平衡氨基酸组、酪蛋     

大豆高支链氨基酸混合物营养价值的研究

大豆高支链氨基酸混合物是水解大豆蛋白质添加少量个别氨基酸制成的氨基酸混合物。其必需氨基酸含量占混合物的68.9％,支链氨基酸含量占42.9％。 动物喂养实验显示,此种氨基酸混合物能促进幼年大鼠生长,维持血红蛋白、血清总蛋白和白蛋白的正常含量,蛋白质功效比值(PER)、真消化率(TD)、生物价值(BV)、净蛋白质利用率(NPU)依次为2.78、94.0％、85.0％和80.0％。这些值均显著高于酪蛋白、略高于大豆平衡氨基酸,表明此种氨基酸混合物没有因支链氨基酸含量高而发生氨基酸拮抗作用,具有较高的营养价值。     

蚕豆蛋白粉的营养评价

蚕豆是我国种植较广的豆科植物,含蛋白质23.59％,属高蛋白食物。蚕豆蛋白质的限制氨基酸为含硫氨基酸和色氨酸。用蚕豆蛋白粉饲养大鼠,测得蛋白质功效比值(PER)为0.82～1.19;净蛋白质比率(NPR)为2.25～2.48;生理价值(BV)为47.90～49.50％;净蛋白质利用率(NPU)为45.50～46.10％;真消化率(TD)为91.70～95.90。与酪蛋白粉组相比,除真消化率相近外,其余四项指标均较酪蛋白粉组低(P≤0.05)。蚕豆蛋白质中含硫氨基酸及色氨酸低,可与其他蛋白质食物混合使用,改变必需氨基酸构成比值,提高其营养价值。蚕豆是应予以重视的植物性蛋白质资源。     

强化大豆平衡氨基酸营养价值的研究

强化大豆平衡氨基酸是用酸水解大豆蛋白,添加蛋氨酸和色氨酸后制成的氨基酸混合物。必需氨基酸种类齐全,组织平衡,含量达46.5％。氨基分(AAS)、化学分(CS)、必需氨基酸指数(EAAI)各为0.97、55、91.53,均优于酪蛋白。动物试验表明,可促进幼年大鼠生长,蛋白质功效比值(PER)为3.38±0.23,净蛋白化率(NPR)为4.65±0.34真消化率(TD)为96 44±1.02,生物价(bV)为77.06±1 41、净蛋白利用率(NPU)     

蛋白质补充品的研究——Ⅱ.不同加热处理法制备的黄豆粉和花生蛋白粉的营养效用

用理化和生物学的方法对湿热处理黄豆粉、远红外线烘干黄豆粉、膨化黄豆粕粉和用碱液提取后浓缩喷干花生蛋白粉进行了检测,对其蛋白质营养价值进行了综合评定。 2.三种黄豆粉的尿酶和胰蛋白酶活力均为阴性,说明三种加热方法均可使抗营养因子失活。三种豆粉中蛋白质含量在39—49％,每100g粗蛋白质中赖氨酸总量高达6g左右,其中可利用赖氨酸含量湿热处理豆粉为6.05g,远红外烘干豆粉为4.82g,膨化豆粉为5.18g。食膨化豆粉的大鼠的肝、肾,甲状腺、胰腺病理组织学检查未见异常。湿热处理豆粉,远红外线烘干豆粉和膨化豆粉的校正蛋白质功效比值(EPR)(以标准酪蛋白为2.40)分别为2.06、1.86、和1.91,真消化率(TD)分别为91.9、87.2和86.2％,生理价值(BV)分别为67.8、58.8和59.4％,净蛋白质利用率(NPU)分别为62.4、51.3、51.3％,湿热处理豆粉与酪蛋白的校正PER(2.40)、BV(69.9％)和NPU(67.9％)无显著差异,但均显著高于远红外线烘干豆粉和膨化豆粉,这些结果说明这三种加热方法中以湿热处理豆粉的方法较好。 3.花生蛋白粉的蛋白质含量高达70.2％,但氨基酸模式不平衡,缺少赖、苏、蛋、色氨酸。每100g粗蛋白中可利用赖氨酸仅2.89g。校正蛋白质功效比值(PER)为1.32。真消化率(TD)虽高于其他各组,但生理价值(BV)和净蛋白质?     

水解乳清蛋白对生长期大鼠氮代谢影响的研究

目的:观察水解乳清蛋白对生长期大鼠氮代谢的影响. 方法:40只大鼠随机分为实验组和对照组.实验组饲料氮源为水解乳清蛋白(乳清蛋白肽),对照组饲料氮源为浓缩乳清蛋白(未水解乳清蛋白).主要观察指标为蛋白质功效比值( PER)、蛋白质表观消化率(AD)和动物体重变化情况. 结果:实验组大鼠PER和AD值均显著高于对照组,实...     

猪全血蛋白质营养价值的评价

猪全血蛋白质的赖氨酸含量高(7.8g/16gN),异亮氯酸含量低(0.5g/16gN),为第一限制氨基酸,亮氨酸/异亮氨酸比值(26/1)过高。猪全血蛋白质的真实消化率(TD)、生物价(BV)和净蛋白质比值(NPR)分别为92.4％,16.5和0。大鼠体重下降。蛋白质功效比值(PER)不能计算,表明其营养价值差。但它与面粉蛋白质有很好的互补作用,全血蛋白质与面粉蛋白质2∶8混合为最佳比例(相当于在面粉中添加3％的猪血粉),其营养价值显著提高,BV、PFR和NPR分别从面粉的55.3、1.01和3.1上升至77.3、2.46和4.3。     

秋葵籽蛋白质的营养学研究

对野生植物秋葵籽、去油后的秋葵籽饼的营养成分及有害物质进行了分析,并以大豆蛋白及酪蛋白为对照,通过动物实验对其蛋白质营养价值进行了研究。结果表明,秋葵籽和秋葵籽饼蛋白质含量分别为28.1％和32.2％,第一限制氨基酸为异亮氨酸。秋葵籽蛋白质营养价值低于大豆蛋白,而秋葵籽饼蛋白质营养价值与大豆蛋白接近。     

Mediterranean milk and milk products

Milk and dairy products are part of a healthy Mediterranean diet which, besides cow's milk, also consists of sheep's, goat's and buffalo's milk--alone or as a mixture---as raw material. The fat and protein composition of the milk of the various animal species differs only slightly, but in every case it has a high priority in human nutrition. The milk proteins are characterized by a high content of essential amino acids. Beyond that macromolecules,which have various biological functions, are available or may be formed by proteolysis in milk. Taking this into consideration, the technology of different well-known Italian and German cheese types is presented and the differences as well as correspondences regarding nutrition are discussed. Especially Ricotta and Mascarpone are discussed in detail. Ricotta represents a special feature as this cheese is traditionally made of whey and cream. Thus the highly valuable whey proteins which contain a higher amount of the amino acids lysine, methionine and cysteic acid in comparison to casein and, additionally, to soy protein, are made usable for human nutrition. Finally, it is pointed out on the basis of individual examples that technologies to enrich whey proteins in cheese are already available and in use. Thus, the flavor of low fat cheese is improved and the nutritional value is increased.     

Specialized formulas and feedings for infants with malabsorption or formula intolerance

The composition of specialized formulas for infants who experience malabsorption or formula intolerance is described in detail. The limited studies of efficacy, as well as a rationale for selecting an appropriate formula for infants with malabsorption or formula intolerance, are discussed. Infants with symptoms of diarrhea or emesis may have intolerance to milk lactose or milk protein. Soy formulas contain no lactose or cow's milk and should be the first choice of an alternative feeding because of cost and convenience. Some infants may be intolerant of soy as well as cow's milk protein. They benefit from formula containing neither cow's milk nor soy protein or from a specially processed milk-based formula containing hydrolyzed casein. A carbohydrate-free formula to which the desired type of carbohydrate is added may be helpful in the diagnosis and treatment of disaccharidase deficiencies and monosaccharide intolerances. Infants with extensive intestinal resections or intractable diarrhea may require specialized infant formulas with qualitative/quantitative modifications of fat, carbohydrate, and protein. Formulas with medium-chain triglycerides may be useful for infants with steatorrhea. "Preterm" formulas or milk from the infant's mother are preferred for preterm infants, since such feedings promote improved fat and carbohydrate absorption and better meet the infant's nutrient requirements.     

Copper absorption from human milk, cow's milk, and infant formulas using a suckling rat model

Since copper deficiency is known to occur during infancy, it becomes important to assess copper uptake from various infant diets. We have investigated the uptake of copper from human milk, cow's milk, cow's milk formulas, cereal/milk formula and soy formula, compensating for the decay of 64Cu and using the suckling rat as a model. Radiocopper was added to the diet in trace amounts. Ultracentrifugation, ultrafiltration, and gel filtration were used to show that the added 64Cu bound to milk fractions and individual binding compounds in a manner analogous to the distribution of native copper, thus validating the use of extrinsically labeled diets. Labeled diets were intubated into 14-day-old suckling rats. Animals were killed after 6 h and tissues removed and counted. Liver copper uptake was 25% from human milk, 23% from cow's milk formula, 18% from cow's milk, 17% from premature (cow's milk based) infant formula, 17% from cereal/milk formula and 10% from soy formula. These results show that the rat pup model may provide a rapid, inexpensive, and sensitive method to assay bioavailability of copper from infant foods.     

脱脂蓖麻蛋白的营养与食品卫生学研究

本文用化学分析和动物实验的方法研究了内蒙产脱脂蓖麻蛋白的去毒及去毒后的营养与食品卫生质量。结果表明,脱脂去毒蓖麻蛋白的营养质量较好,食品安全性较为可靠,可以作为食物蛋白质的资源开发和利用。     

鱼蛋白粉(浓缩鱼蛋白FPC)的营养价值

<正> 鱼含有丰富的蛋白质,自古以来即为人类膳食中重要蛋白质来源之一。鱼肌细嫩、其蛋白质的氨基酸组成比值,较其它动物性蛋白质更接近于婴儿的营养需要。 为了做好儿童保健工作,因地制宜寻找优良蛋白质食物以补充母乳量的不足,我院在1963年采用熟鲜鱼肉补充母乳以喂养婴儿,所得结果,非常令人满意。因之,我们与上海鱼品厂协作制备脱脂鱼蛋白粉,以供缺乏鲜鱼地区之用,又与中国医学科学院营养系协作,进行鱼蛋白粉的化学分析和动物实验。     

Treatment of dietary casein with formaldehyde reduces its hypercholesterolemic effect in rabbits

Rabbits were fed cholesterol-free, semipurified diets containing 42% (wt/wt) casein or 21% casein plus one of the following nitrogen sources: soy isolate, amino acid mixture simulating casein, amino acid mixture simulating soy isolate, formaldehyde-treated casein or formaldehyde-treated soy isolate. Two additional groups of rabbits were fed the 42% casein diet and the diet containing casein plus soy isolate to which 0.4% (wt/wt) pure formaldehyde was added, this amount being identical to the amount of formaldehyde present in the diets with formaldehyde-treated proteins. Growth was somewhat reduced on the three diets containing 42% casein. The diet containing 42% casein to which no formaldehyde had been added induced severe hypercholesterolemia, the level of serum cholesterol after 8 weeks being about 10 mmol/L. The hypercholesterolemia was markedly reduced by the replacement of half of the casein by soy isolate, formaldehyde-treated soy isolate or formaldehyde-treated casein. No significant reduction of the concentration of serum cholesterol was seen when half of the 42% casein was replaced by an amino acid mixture imitating either casein or soy isolate. Formaldehyde per se did not significantly influence the level of serum cholesterol. We conclude that the differential tertiary structure of intact casein and soy isolate is an important factor in determining the cholesterolemic responses in rabbits to these proteins.     

Hepatic cysteine dioxygenase activity and sulfur amino acid metabolism in rats: possible indicators in the evaluation of protein quality

Experiments were carried out to examine the possibility that the sulfur amino acid metabolism of rats may be an indicator of the nutritional value of dietary protein. Rats were fed diets containing 8, 16 or 24% of gluten, soy protein or casein for 3 wk. Hepatic cysteine dioxygenase activity, hepatic concentration of glutathione, cysteine and taurine and urinary taurine were examined. In addition, the sulfur amino acid metabolism of rats fed these diets fortified with the appropriate first limiting amino acid for 7 d was also examined. High urinary taurine excretion was observed in the three gluten groups, whereas very low urinary taurine excretion was observed with up to 24% soy protein or up to 16% casein. The hepatic hepatic cysteine dioxygenase activities of the gluten diet groups were higher than those of corresponding soy protein or casein diet groups, except that of rats fed the 24% casein diet. The hepatic concentrations of both glutathione and cysteine in gluten diet groups were also higher than those of corresponding soy protein or casein diet groups, except 24% soy protein and 16 and 24% casein diet groups. In rats fed the casein or soy protein diets urinary taurine excretion and hepatic cysteine dioxygenase activity increased with increasing methionine supplementation, the first limiting amino acid. Conversely, in rats fed the gluten diet both urinary taurine excretion and hepatic cysteine dioxygenase activity decreased with increasing lysine supplementation, the first limiting amino acid. These findings suggest that urinary taurine excretion and hepatic cysteine dioxygenase activity may be useful as sensitive indicators of the nutritional value of dietary protein.     

Safety of soy-based infant formulas containing isoflavones: the clinical evidence

Soy protein has been used in infant feeding in the West for nearly 100 y. Soy protein infant formulas have evolved in this interval to become safe and effective alternatives for infants whose nutritional needs are not met with human milk or formulas based on cow's milk. Modern soy formulas meet all nutritional requirements and safety standards of the Infant Formula Act of 1980. They are commonly used in infants with immunoglobulin E-mediated cow's milk allergy (at least 86% effective), lactose intolerance, galactosemia, and as a vegetarian human milk substitute. Largely as a result of research in animal models, concerns have been voiced regarding isoflavones in soy infant formulas in relation to nutritional adequacy, sexual development, neurobehavioral development, immune function, and thyroid disease. We discuss the available clinical evidence regarding each of these issues. Available evidence from adult human and infant populations indicates that dietary isoflavones in soy infant formulas do not adversely affect human growth, development, or reproduction.     

Effect of supplementing low protein diets with the limiting amino acids on the excretion of N1-methylnicotinamide and its pyridones in rats

We have hypothesized that the ratio of the excreted by-products of niacin metabolism, N1-methyl-2-pyridone-5-carboxamide (2-pyr) + N1-methyl-4-pyridone-3-carboxamide (4-pyr)/N1-methylnicotinamide (MNA), might be useful as an index to assess the adequacy of amino acid intake in rats. The experiment reported herein was performed to test this hypothesis. When a 10, 20 or 40% casein diet supplemented with 0.1, 0.2 or 0.4% L-methionine, respectively, was fed to rats, the urinary excretion of MNA decreased, and that of 4-pyr increased, as the level of dietary casein and methionine increased. Therefore, the ratio of (2-pyr + 4-pyr)/MNA increased with increasing dietary casein and methionine levels. When the limiting amino acids of casein or soy protein isolate were added to a low casein or low soy protein isolate diet, the urinary ratio of (2-pyr + 4-pyr)/MNA also increased. These results indicate that the increased urinary ratio of (2-pyr + 4-pyr)/MNA can serve as a biological marker for adequate amino acid intake.