Protein quality measures determined in two allegedly poor quality fish meals and in two commercial capelin meals

Protein quality indices (PER, nitrogen balance, digestibilities of protein, methionine and lysine) were obtained for two allegedly poor quality fish meals of unknown origin and for two Norwegian capelin meals. The former two contained 40 and 50%, the latter two, 6 and 12% of their methionine in the form of methionine sulphoxide. A high sulphoxide content was associated with poor protein quality. Thus, autoxidation during production or storage may affect fish meal protein differently from oxidation with hydrogen peroxide in the laboratory. Methionine supplementation did not improve the PER-values of any of the meals. This indicates that methionine was probably not the first limiting amino acid for protein utilisation in these meals for the young rat.     

紫果西番莲和其它5种水果中氨基酸组分分析

对紫果西番莲、香蕉、芒果、脐橙、木瓜和火龙果6种水果中的17种氨基酸的含量组成和营养评估进行了研究。总氨基酸含量从大到小为:紫果西番莲 > 香蕉 > 火龙果 > 芒果 > 脐橙 > 木瓜。必需氨基酸含量从大到小为:香蕉 > 紫果西番莲 > 火龙果 > 芒果 > 木瓜 > 脐橙。6种水果的第一限制氨基酸都是蛋氨酸(Met)。紫果西番莲中含量最高的氨基酸是天冬氨酸(Asp),其次是脯氨酸(Pro)和谷氨酸(Glu)。紫果西番莲必需氨基酸中赖氨酸含量最高,占了必需氨基酸的26.6%。6种水果中紫果西番莲甜味氨基酸,鲜味和酸味氨基酸,苦味氨基酸含量均最高。氨基酸中天冬氨酸(Asp)和谷氨酸(Glu)的含量较高,二者对紫果西番莲的鲜味起到重要的作用。紫果西番莲的风味丰富。     

我国29种青稞的营养及功能组分分析

为了解我国不同青稞品种的营养及功能组分,对29种青稞的成分进行分析,包括碳水化合物、蛋白质、脂肪、氨基酸、灰分、水分及β-葡聚糖、总黄酮。研究结果表明:29种青稞中蛋白质含量变化范围为8.74%~13.16%,脂肪含量变化范围2.44%~4.48%,总氨基酸含量变化范围7.48%~11.86%,β-葡聚糖含量变化范围2.89%~6.11%,总黄酮含量变化范围0.11%~0.28%,灰分变化范围1.66%~2.95%,不同品种之间存在显著性差异;碳水合物和水分的变化范围分别为73.82%~78.30%和7.69%~9.68%,显著性差异不明显。29种青稞中均含有17种氨基酸,包括人体所需的8种必需氨基酸。其中,青稞XZDM00025的蛋白质、总氨基酸和总黄酮含量最高,青稞XZDM00027的β-葡聚糖含量最高,青稞XZDM00074脂肪含量最低。通过对比WHO/FAO理想蛋白质氨基酸模式,青稞的第1限制性氨基酸是甲硫氨酸,第2限制性氨基酸是赖氨酸,第3限制性氨基酸是异亮氨酸。采用聚类分析(组间连接-平方欧式距离)法将29种青稞分为7类,前4类都仅包括1个品种,第Ⅴ类包括6个品种,第Ⅵ类包括2个品种,第Ⅶ类包括17个品种,且各大类间营养和功能含量组分存在显著性差异。     

添加赖氨酸和苏氨酸对小麦面筋蛋白降低大鼠同型半胱氨酸效果的影响

目的在小麦面筋蛋白中添加赖氨酸和苏氨酸,探讨两种限制氨基酸在小麦面筋蛋白中降低大鼠血浆高同型半胱氨酸(Hcy)血症的影响。方法 32只健康Wistar大鼠随机分为4组,分别为大豆分离蛋白组(25S)、酪蛋白组(25C)、小麦面筋蛋白组(29G)、赖氨酸+苏氨酸添加组(29GLT)。各组大鼠分别给予不同饲料喂养14 d后处死,采集血液、肝脏等样品,用于测定生化、酶学指标。结果添加赖氨酸和苏氨酸可有效改善大鼠因摄入小麦面筋蛋白导致的体重、血浆中Hcy的降低,可抑制血浆S-腺苷蛋氨酸(SAM)和肝脏甜菜碱高半胱氨酸甲基转移酶(BHMT)活性的升高,但对胱硫醚β-合成酶(CBS)活性无影响。蛋氨酸含量较低的大豆分离蛋白组,血浆中同型半胱氨酸的含量并未降低。结论小麦面筋蛋白对大鼠血浆同型半胱氨酸浓度的影响可能与其氨基酸的组成特点有关。小麦面筋蛋白的高半胱氨酸和低赖氨酸及低苏氨酸的氨基酸组成是小麦面筋蛋白降低同型半胱氨酸水平的可能因素。     

Estimation of lysine and methionine requirements of growing steers fed corn silage-based or corn-based diets

Methionine and lysine requirements of growing steers were studied. Steers (Experiment 1, 313 kg) fed 6.4 kg of an 80% corn silage diet (1.38% N) had duodenal flows of methionine, cysteine, and lysine of 9.7, 10.7, and 40.2 g/d. Linear increases in plasma methionine and plasma lysine in response to abomasal infusions of DL-methionine and L-lysine indicated that requirements for methionine and lysine were met by basal flows or that neither lysine nor methionine was the first or sole limiting amino acid. Steers (Experiment 2, 383 kg) fed 7.5 kg of a 75% corn diet (1.55% N) had methionine, cysteine, and lysine flows at the duodenum of 13.8, 16.1, and 52.9 g/d. Abomasal infusions of DL-methionine resulted in linear increases in plasma methionine, but abomasal infusions of L-lysine resulted in two-phase broken line plasma amino acid response curves. For steers infused with lysine alone, the breakpoint occurred at 4 g/d infused lysine, whereas steers receiving 9 g/d DL-methionine had a breakpoint at 8 g/d infused lysine. The total absorbable lysine requirement was estimated to be 44 to 48 g/d, depending upon methionine status. Rumen-protected amino acids fed to steers on both dietary regimens were effective in supplying methionine and lysine postruminally.     

Proteins of Italian millet: Amino acid composition,solubility fractionation and electrophoresis of protein fractions

Determination of the protein contents of 14 varieties of Italian millet revealed considerable varietal differences. The total protein of the 14 varieties was fractionated into albumin-globulin, prolamin and glutelin fractions. The prolamin fraction constitutes the major storage protein of the grain. There is a positive correlation between protein content and the prolamin levels of the seeds and the increase in protein content is largely due to an increase in the prolamin content. The amino acid composition of each of 14 varieties of the millet and the individual protein fractions from three varieties were determined. The limiting amino acids are lysine followed by tryptophan and the sulphur containing amino acids, methionine and cystine. The lysine content of the grain decreases with increase in protein content. The total protein has a rather high content of leucine. SDS-polyacrylamide gel electrophoresis of the protein fractions indicated similarities in the prolamin fraction and differences in the albumin-globulin and glutelin fractions of the different varieties.     

The effect of long-term storage of fish meals on the response of chickens to the amino acid supplementation of diets containing such meals.

In three experiments fish meals of different origin and treatment were given to chickens in short-term feeding trials after varying storage periods. Diets were supplemented with amino acids in these experiments, most of which were of factorial design, in such a way that the first limiting amino acids of the meals could be established. The body moisture content of three or four groups of chickens per treatment served as criterion of nitrogen (N) retention by the chickens. In the first experiment consisting of two trials, a pilchard meal stored for over 70 weeks and an anchovy meal stored for 74 weeks were both shown to have methionine as first limiting amino acid but only whenthe former was stabilised with ethoxyquin and the latter was not. Several of the trials in the second experiment involved fish meals stored under nitrogen. Such meals have not been used in similar experiments before. L-lysine hydrochloride supplementation of diets which contained full (i.e. with solubles added) fish meals depressed N retention, as did L-isoleucine when added at a high level (0.5%). This effect of lysine was also demonstrated when used in a diet which contained a commercial pilchard full meal which had been stored for about 6 months. On the other hand, lysine was shown to be the first limiting amino acid of a fish meal to which solubles had not been added. When the stabilised full meal used in Experiment II had been in storage for 108 weeks a positive reponse in chicken N retention to methionine supplementation of diets containing this meal occurred (Trial IId). In subsequent trials with these ageing stabilised meals cystine and/or methionine supplementation and later particularly supplementation with glycine led to better N retention by chickens. Unstabilised stored meals seem to have a sulphur-containing amino acid as first limiting. In most instances where comparison was possible diets containing stabilised fish meals gave greater chicken body N retention than those containing similar unstabilised meal.     

The protein and the amino acid composition of some rice and maize varieties grown in North Vietnam

The protein and amino acid composition of several rice and maize varieties grown in North Vietnam, and their digestibility, was determined. The protein content (N×5.95) of rice cultivars ranged from 7.0 to 10.8% of which 70–80% was in the glutelin fraction. The true digestibility was relatively good (87.6–91.8%). In general, lysine and threonine were found to be the first and second nutritionally limiting amino acids, except for two varieties, which had a low content of sulphur-containing amino acids. The protein content of maize cultivars ranged from 8.4 to 12.9%. Zein and glutelin were the main components occurring in near-equal quantities (except in the opaque-2 mutant). The overall amino acid distribution was similar to that of maize grown in other countries. Lysine levels were relatively low, and it was the first nutritionally limiting amino acid, except in the opaque-2 cultivar, tryptophan being the second one. The digestibility ranged from 87.5 to 91.1%.     

Studies on the proteins of kodo millet (Paspalum scrobiculatum)

Studies on the proteins of five varieties of kodo millet showed that there are hardly any varietal differences. Fractionation of the proteins showed that glutelin is the major storage protein. The amino acid compositions of the protein of the five varities of kodo millet and the individual protein fractions of two varieties were determined. Lysine is the most limiting amino acid followed by methionine and cystine. There is no significant negative correlation between lysine levels and protein content. Sodium dodecylsulphate polyacrylamide gel electrophoresis patterns indicate great similarities in the different varieties.     

Effect of preliminary and culinary processing on amino acid content and protein quality in frozen French beans

The aim of the study was to evaluate the content of amino acids and protein quality of French bean pods. The investigated material consisted of the raw vegetable, fresh pods cooked to consumption consistency, and two kinds of frozen products stored for 12 months at ?20 °C and then prepared for consumption: frozen beans obtained using the traditional method (blanching before freezing) and frozen products of the ready‐to‐eat type (cooking before freezing). A comparison of the amino acid content in the product prepared for consumption showed that the lowest quantities were found in French beans obtained using the traditional method; products obtained using the modified technology and beans cooked directly after harvest had similar levels of most amino acids. The content of amino acids in 16 g N was less varied than in 100 g of the product. The protein in all the three products prepared for consumption as well as that in fresh bean pods hardly differs, as confirmed by the values in the essential amino acid index (EAA). The first limiting amino acid was methionine with cystine and the second was lysine.     

Limiting amino acid for protein synthesis with mammary cells in tissue culture.

To identify the limiting amino acid in the minimal essential medium as published by Eagle (Science 130:432, 1959) for milk protein synthesis in rat mammary cells in tissue culture, two different experimental approaches were used. The first study involved the reduction of amino acids singly from the total amino acid complement of the medium for milk protein synthesis. The second study was to investigate the effect on milk protein synthesis of single amino acid addition to the basic complement of amino acids. Order of limiting amino acids was lysine (first) and possible methionine, valine, or arginine (second).     

Chemical composition,amino acid content and protein quality of Canavalia spp. seeds

Canavalia ensiformis is a grain legume that offers good possibilities for its use, but reports on its chemical composition and nutritive quality are not readily available. This study presents chemical and nutritional data on C. ensiformis, C. gladiata and C. maritima grains. The three species varied in protein content mainly because of differences in crude fibre content. Protein varied from 26.9 to 22.4%, and crude fibre varied from 8.5 to 17.3%. This was due to differences in seed-coat percentage. The amino acid content in C. ensiformis and C. gladiata was essentially the same, and both were deficient in sulphur-containing amino acids but rich in lysine. Pressure cooking and roasting reduced lysine levels. Mineral content in the three species was essentially the same, with high potassium levels as is the case with most food legumes. Feeding trials indicated low nutritional quality for the raw grain, which was significantly improved by pressure cooking and roasting. Protein digestibility was 47.9%, and cooked and roasted samples had 76.4 and 78.7%, respectively. Both C. ensiformis and C. gladiata had the same protein quality (PER = 1.24), and it was significantly improved with methionine supplementation.     

马关县不同产地草果氨基酸组成与分析

目的 研究马关县不同产地草果中氨基酸含量与组成。方法 采用Biochrom30+型氨基酸分析仪检测5个乡镇产草果中氨基酸。结果 草果M2、M4、M5检出17种氨基酸,7种必需氨基酸;草果M1、M3检出16种氨基酸,未检出蛋氨酸,且不同产地草果的氨基酸具有差异。草果TAA为36.02mg/g～45.79mg/g,EAA为14.71mg/g～16.42mg/g,以谷氨酸(6.67mg/g),天冬氨酸(4.72mg/g)含量较高。氨基酸比值系数法显示草果中蛋氨酸+胱氨酸、赖氨酸均为不足,亮氨酸、苯丙氨酸+酪氨酸、缬氨酸均为过剩,第一限制性氨基酸为蛋氨酸+胱氨酸。草果中呈味类氨基酸和药用氨基酸含量丰富,分别占TAA的89%、64%。SRC比值系数分显示草果M2得分最高,为65.40。结论 不同乡镇产草果中的氨基酸含量有显著差异,综合分析氨基酸营养价值最高的是草果M2。     

太门哲罗鲑成熟卵子营养成分分析及评价

以太门哲罗鲑成熟卵子为研究对象,对常规营养成分、氨基酸组成、必需氨基酸营养品质评价和脂肪酸组成进行测定分析。结果表明：太门哲罗鲑成熟卵子（鲜样）中粗蛋白质量分数33.450%、粗脂肪质量分数6.432%、水分质量分数56.683%、灰分质量分数3.418%;17 种氨基酸中人体必需氨基酸7 种,非必需氨基酸10 种,氨基酸总量高达26.823%,必需氨基酸含量11.677%,非必需氨基酸含量15.146%,其中含量最高的为谷氨酸（2.931%）,其次为亮氨酸（2.627%）、丙氨酸（2.370%）、赖氨酸（2.142%）,均高于2.000%;必需氨基酸的构成比例基本符合联合国粮农组织/世界卫生组织的标准,以氨基酸评分来评价,第一限制性氨基酸为缬氨酸,第二限制性氨基酸为蛋氨酸＋半胱氨酸;以化学评分评价,第一限制性氨基酸为蛋氨酸＋半胱氨酸,第二限制性氨基酸为缬氨酸。必需氨基酸指数高达81.905。25 种脂肪酸中含饱和脂肪酸8 种,饱和脂肪酸总量占太门哲罗鲑成熟卵子1.308%,占总脂肪酸为22.497%;不饱和脂肪酸17 种,其中单不饱和脂肪酸6 种、多不饱和脂肪酸11 种,不饱和脂肪酸总量占成熟卵子高达4.483%,占总脂肪酸比例高达77.503%。通过上述分析得出,太门哲罗鲑成熟卵子可作为理想的蛋白质、氨基酸和脂肪酸来源。     

Biochemical changes in developing wheat grains. Changes in nitrogen fractions,amino acids and nutritional quality

Two spring wheat cultivars (Triticum aestivum L. em Thell.), one tall (Chris) and the other semi-dwarf (Era), with different yields and grain protein potentials, were grown in controlled environment chambers to compare the nitrogen fractions, amino acids and nutritional quality in developing grains at 12, 22, 29 and 36 days after heading. The proportions of gliadin I, gliadin II and glutenin II increased and those of albumin and globulin decreased as the wheat cultivars matured. The amount of lysine, methionine, threonine, valine, tyrosine, alanine, aspartic acid and glycine was lower and that of glutamic acid and proline was higher with grain development in both cultivars. At 12 days after heading Era had a higher content of amino acids (16 g^?1 N) than Chris. Isoleucine was the first limiting amino acid in Era and Chris at the first collection period whereas at later stages lysine was the limiting amino acid in both cultivars. Chemical score, essential amino acid index, requirement index and calculated biological value all decreased as the grain matured and, except for the 12-days collection period, the data were almost similar for both the cultivars.     

不同产地藜麦籽氨基酸组成及其营养价值评价

采用氨基酸自动分析仪测定青海、云南、秘鲁、河北、玻利维亚等地产的15种藜麦籽的氨基酸组成,并对其氨基酸营养价值进行评价。结果表明:不同产地藜麦籽的总氨基酸含量为9.81%~12.68%,EAA/TAA的范围为34.5%~36.0%,EAA/NEAA范围为52.0%~56.0%,其中沽源县白色藜麦籽(Q13)EAA/TAA为36.0%,EAA/NEAA为56.0%,品质最佳,可作为藜麦籽蛋白产品开发与利用的理想资源。藜麦籽氨基酸比值系数分(SRC)均值为88.9,含硫氨基酸(甲硫氨酸、半胱氨酸)的氨基酸比值系数(RC)最小,为第一限制性氨基酸,与甲硫氨酸和胱氨酸含量较高的食品一起食用,可以提高食用价值。     

大麦在发芽过程中营养物质的变化及其营养评价

通过测定发芽大麦中的蛋白质、脂肪、淀粉、氨基酸、还原糖、β-葡聚糖、总膳食纤维、可溶性膳食纤维、不溶性膳食纤维、VB1和VB2的含量,研究发芽时间对大麦营养价值的影响。结果表明：发芽过程中,总干物质有一部分降解,蛋白质、淀粉和脂肪均呈下降趋势;但可溶性低分子糖类、含氮物质和维生素含量有很大提高,其中还原糖含量上升2.78%～14.36%,总氨基酸含量增加了8.15%,且7种必需氨基酸含量均逐渐增加,赖氨酸增幅最大（32%）。与未发芽大麦相比,VB2含量增长了17.8倍;VB1含量变化不大;β-葡聚糖呈下降趋势;可溶性膳食纤维增加。发芽过程中,必需氨基酸/总氨基酸值和必需氨基酸指数增加,必需氨基酸组成模式更加符合联合国粮食及农业组织/世界卫生组织联合食品标准计划,第一限制氨基酸由原来的赖氨酸转变为蛋氨酸+胱氨酸。结论：发芽在一定程度上提高了大麦的营养价值,但对其在利用β-葡聚糖相关功能特性方面有一定的限制。     

Amino acid composition and In Vitro digestibility of some protein fractions from three species of leaves of various ages

Extracts from leaves of barley (Hordeum vulgare), lupin (Lupinus albus) and Chinese cabbage (Brassica chinensis) of different ages were fractionated. As the leaves age, chloroplasts are increasingly disrupted during extraction and the chlorophyll-containing protein becomes increasingly difficult to sediment. The amount of protein unassociated with chlorophyll varies with species, but not with leaf age. Analyses are given of selected chloroplastic fractions (sedimented and coagulated) and of the protein precipitated from the whole extracts and the various supernatant fluids. Amino acid composition of unfractionated protein is independent of species, except perhaps for methionine; leaf age has no affect on composition. The method of protein precipitation may influence the amount of lysine determined. Contrary to previous reports, chloroplastic and cytoplasmic protein do not have the same composition. Nutritional properties of the preparations are discussed in relation to their amino acid composition and to their known in vivo and in vitro behaviour. Comparison with the F.A.O. reference protein shows that sufficient lysine, both total and nutritionally ‘available’, is present in unfractionated and cytoplasmic protein, though it may be marginal in some chloroplastic fractions. The first limiting essential amino acid in all leaf protein preparations is methionine, and there is an adequate amount ‘available’ in cytoplasmic but not in unfractionated or chloroplastic protein. Reasons are suggested for the unavailability of methionine, and possibly cyst(e)ine, in the latter preparations.     

不同规格胭脂鱼的营养成分分析和安全性评价

目的 为了比较分析不同规格胭脂鱼的营养价值和安全性。方法 以小、中、大3种规格的胭脂鱼为研究对象,测定基本营养成分、氨基酸组成、重金属含量和兽药残留量。结果 胭脂鱼规格越小,水分、粗蛋白含量越高,粗脂肪、粗灰分含量越低。不同规格胭脂鱼中均检出17种氨基酸,总量分别为20.70、17.90、20.18 g/100g,其中谷氨酸平均含量(2.88 g/100g)最高,其次是天冬氨酸,为1.95 g/100g,是鲜味氨基酸的主要组成部分,胭脂鱼中富含7种必需氨基酸,含量最高的为赖氨酸,必需氨基酸与非必需氨基酸百分比为64.01%～65.45%,均符合(Food and Agriculture Organization of the United Nations/World Health Organization)FAO/WHO推荐的理想蛋白模式;根据氨基酸评分和化学评分结果可知,胭脂鱼第一限制性氨基酸均为甲硫氨酸和胱氨酸;3种规格胭脂鱼的必需氨基酸指数分别为101.99、90.16和98.51。胭脂鱼中Pb、Cd、Cr、无机As和甲基Hg等5种重金属均符合食品安全国家标准,且未检出氯霉素、硝基呋喃等兽药残留。结论 综上表明胭脂鱼一种高蛋白低脂肪、氨基酸组成理想、食用安全的高价值鱼类;小规格的胭脂鱼粗蛋白、氨基酸总量和必需氨基酸指数最高,营养价值相对更高。     

菜籽蛋白氨基酸组成分析及与功能特性的相关性研究

选用长江上游、中游和下游的30个菜籽品种的饼提取蛋白质,对蛋白质进行氨基酸组成和功能特性的研究.结果表明:菜籽蛋白中总氨基酸含量为68.67％～84.90％,其中中双11号(湖南)氨基酸总量最高,而丰油730号最低;30个菜籽蛋白中的氨基酸种类齐全,必需氨基酸占氨基酸总量的37％～38％,绝大部分样品的第一限制氨基酸是蛋氨酸,氨基酸比值系数分(SRC)为77.66～91.53.在营养分析的基础上,建立氨基酸组成与功能特性的相关性分析,分析结果为:亲水性氨基酸含量与乳化稳定性呈显著负相关,乳化性与乳化稳定性呈极显著负相关,可溶性蛋白含量与吸油性、吸水性、起泡性呈正相关.菜籽蛋白是营养价值很高的植物蛋白,可广泛应用于食品工业.