Amino acid analyses of cereal flour proteins

Amino acid analyses have been made on flours of wheat, rye, barley, oats and maize. The overall pattern is sufficiently similar (particularly between rye and barley) to indicate a common ancestor, but significant individual differences occur. Wheat protein differs from the other four in its higher capacity for polar and H-bonds and lower content of salt links. Other factors such as S.S interchange potential may be more important than the pattern of intermolecular forces since the latter does not change much from rye to barley in spite of their rheological differences. The factors for conversion of nitrogen to protein are, in the above order, 5.7, 5.8, 5.8, 5.7, 5.9.     

Use of scanning electron microscopy to indicate the similarities and differences in pseudocereal and cereal proteins

Isolated and separated protein fractions from cereal and pseudocereal grains were analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis and scanning electron microscopy. Prolamin, the main storage protein in cereal such as maize, showed a difference in electrophoretic patterns and fine structure in comparison with those from amaranth and soybean. In contrast glutelins from amaranth, soybean and maize showed some similarity in the distribution of protein bands and in microstructure. Amaranth and soybean were closely similar in distribution of protein fractions and their microscopic structure. As an addition to chemical analyses, microscopy helped to understand and visualize structural changes and textural differences in protein fractions. Pseudocereals can be used as a nutritive substitute of some cereals in functional foods.     

氨基酸分析仪测定玉米浆中17种游离氨基酸的不确定度评定

依据GB/T 18246-2000,应用氨基酸分析仪测定了玉米浆中17种游离氨基酸含量。在此基础上,应用\     

氨基酸自动分析仪法测定云南新鲜羊肚菌中16种氨基酸的含量

目的 建立氨基酸自动分析仪法测定和分析云南新鲜羊肚菌中16种氨基酸含量的方法。方法 样品匀浆后采用酸水解处理, 使用氨基酸自动分析仪法测定样品中的氨基酸含量。通过计算氨基酸总含量, 必需氨基酸比值, 呈鲜味氨基酸比值等对云南羊肚菌中的氨基酸进行分析。结果 16种氨基酸在10~150 nmol/mL的浓度范围内线性关系良好, 相关系数为0.9988~0.9999, 检出限为1.0~2.5 mg/100 g, 定量限为3.0~7.5 mg/100 g, 16种氨基酸的加标回收率为88.2%~105.2%, 相对标准偏差为3.95%~11.67%。云南新鲜羊肚菌中均含所测16种氨基酸, 平均含量为3.298 g/100 g, 必需氨基酸占总氨基酸总量的35.8%~38.0%。其中谷氨酸和天冬氨酸是含量最高, 占到氨基酸总量的21.8%~24.4%。结论 氨基酸自动分析仪法测定羊肚菌中氨基酸具有重现性好、结果可靠的优点; 云南羊肚菌中氨基酸含量丰富, 各州市间样品间氨基酸含量相对稳定。     

直接氨基酸法测定乳清粉中氨基酸

本文通过使用氨基酸直接分析法——离子交换色谱-积分脉冲安培法（HPIC—IPAD）对乳清中游离的氨基酸和水解后乳清粉中的氨基酸进行检测分析。结果表明，可以检测到孔清粉中含有游离氨基酸6种，水解以后可以检测到15种氨基酸．而且氨基酸的保留时间（Rt）相对标准偏差（RSD）平均为1．843％，峰面积RSD平均为2．6174％。     

腰果蛋白的功能特性研究及其氨基酸组成分析

采用碱提法最优条件提取并酸沉得到腰果蛋白,研究了p H和温度对腰果蛋白的溶解性、起泡性及起泡稳定性、乳化性及乳化稳定性、持油性等功能特性的影响,并分析了腰果蛋白的氨基酸组成。结果表明:腰果蛋白的溶解性随p H的增加呈先降低后升高的趋势,在p H4附近溶解度最低,仅为15.90%。起泡性和乳化性随p H的变化曲线与溶解度曲线一致,在p H10时起泡性和乳化性最好,分别为13.92%、24.70 m2/g。腰果蛋白的起泡稳定性随p H的增加而逐渐增加,在p H8时达到最大为9.42%,而后趋于稳定。在碱性环境中,腰果蛋白会表现出较好的乳化稳定性,并且在80℃时其持油性最佳,为2.84 g/g。氨基酸分析表明,腰果蛋白中含有17种氨基酸,其中7种是人体必需氨基酸,含量皆高于FAO/WHO/UNO成人推荐标准,赖氨酸为第一限制性氨基酸,谷氨酸和精氨酸含量最高,分别为22.46%和9.02%。      

Gross and true ileal digestible amino acid contents of several animal body proteins and their hydrolysates

Amino acid compositions of ovine muscle, ovine myofibrillar protein, ovine spleen, ovine liver, bovine blood plasma, bovine blood globulins and bovine serum albumin and the amino acid compositions and in vivo (laboratory rat) true ileal amino acid digestibilities of hydrolysates (sequential hydrolysis with Neutrase, Alcalase and Flavourzyme) of these protein sources were determined. True ileal amino acid digestibility differed (P < 0.05) among the seven protein hydrolysates. The ovine myofibrillar protein and liver hydrolysates were the most digestible, with a mean true ileal digestibility across all amino acids of 99%. The least digestible protein hydrolysate was bovine serum albumin with a comparable mean true ileal digestibility of 93%. When the digestible amino acid contents were expressed as proportions relative to lysine, considerable differences, across the diverse protein sources, were found in the pattern of predicted absorbed amino acids.     

Milk protein response to abomasal or mesenteric vein essential amino acid infusion in lactating dairy cows

Previous experiments performed at our location suggested that the milk protein response to infusions of mixed essential amino acids (EAA) was greater when these were supplied via intravenous rather than abomasal or duodenal routes. However, as far as we are aware there have been no direct comparisons of the milk protein response to site of EAA provision in the same animals. Our objective was to directly compare the milk protein responses when cows were given mixtures of EAA provided via abomasal or mesenteric vein infusions. Four multiparous, ruminally cannulated, multicatheterized Holstein x Friesian cows averaging 18 wk postpartum were fed dehydrated alfalfa, grass silage, and low protein (11.9% CP, DM basis) concentrates at 30, 20, and 50%, respectively, of dry matter (DM) offered. Total mixed rations (14% crude protein, DM basis) were fed daily as 3 equal meals at 8-h intervals and 95% of ad libitum DM intake. The experimental design was a single reversal with two 10-d infusion periods separated by a 10-d rest period. Each infusion period consisted of 4-d control infusions into the mesenteric vein (saline at 2 ml/min) and abomasum (water at 9 L/d) followed by 6-d infusion of a mixture of EAA equal to 400 g of milk protein/d into the abomasum or mesenteric vein. Control infusions continued into the site not receiving EAA. Intake of DM (20.3 kg/d), milk yield (28.9 kg/d), and milk fat concentration (41.2 g/kg) were not affected by EAA infusions. Milk protein concentration (33.4 vs 34.6 g/kg) and output (938 vs. 982 g/d) were increased and milk lactose concentration was decreased (46.6 vs. 46.1 g/kg) by EAA, but the responses were not affected by infusion site. Recovery of EAA as increased milk protein output (10.9%) was similar for intravascular and abomasally infused EAA in these cows, but these responses were low compared with published effects of postruminal casein infusion.     

Analysis of free amino acids in cereal products

Free amino acids were extracted from cereal products using 50% ethanol to prevent solubilization of polysaccharides and other viscous polymers and to avoid starch gelatinization. The extracts were analyzed by GC after ion-exchange solid phase extraction and chloroformate derivatization using Ez-Faast technology (Phenomenex). Free amino acids in cereal products could be analyzed within 1 h of extraction and determination, with good separation between peaks and repeatable retention times. Relative correction factor for each amino acid was established. The matrix did not affect the results and the method was repeatable for most of the amino acids (coefficient of variation was in the order of 10%). Different fractions and products of wheat, rye, oats and barely were analyzed. The bran contained more free amino acids than did the other analysed fractions of cereals. Fermentation seemed to consume free asparagine and aspartic acid and to use or release other amino acids.     

全自动氨基酸分析仪测定酱油中游离氨基酸的不确定度评定

该实验评定了全自动氨基酸分析仪测定酱油中游离氨基酸的不确定度。参考 CNAS-GL 006—2019《化学分析中不确定度的评估指南》和JJF 1059.1—2012《测量不确定度评定与表示》中的规定与要求,分析游离氨基酸在测定过程中的各种不确定度来源。在包含因子k=2时,酱油中游离氨基酸的扩展不确定度范围为0.02～0.60 g/100 g。结果表明,影响不确定度的主要因素是仪器本身的不确定度和酱油重复性测量的不确定度。     

Fatty acid and free amino acid content of some mushrooms

Free amino acids and fatty acids of seven Basidiomycetes belonging to the families Hygrophoraceae and Russulaceae were determined. Pro, Glu, Ser and Val are the main free amino acids. Linoleic, oleic and palmitic acids are essentially the only fatty acids.     

Ileal amino acid digestibility of some novel dietary protein sources for growing chickens

The apparent ileal digestibility coefficients of amino acids in five high‐protein ingredients (casein, isolated soyprotein, maize gluten meal, spray‐dried bovine plasma (SBP) and spray‐dried porcine plasma (SPP)) and soybean meal were determined using 3‐week‐old broiler chickens. The amino acids in casein were highly digestible. Isolated soyprotein was also well digested by the birds, but the digestibility coefficients of all amino acids in isolated soyprotein were lower (P < 0.05) than those in casein. The amino acid digestibility coefficients in isolated soyprotein were greater (P < 0.05) than those in soybean meal, which may be reflective of reduced concentrations of anti‐nutritive factors, particularly indigestible oligosaccharides. The digestibilities of amino acids in maize gluten meal were higher (P < 0.05) than those in soybean meal, except for the digestibilities of arginine, histidine, threonine and aspartic acid, which were similar (P > 0.05) between the two protein sources. The ileal digestibilities of all indispensable amino acids in SBP and SPP were lower (P < 0.05) than those in casein and isolated soybean meal but higher (P < 0.05) than those in soybean meal. No differences (P > 0.05) were observed in the digestibility of amino acids between SBP and SPP. The overall mean amino acid digestibility coefficients of casein, isolated soyprotein, soybean meal, maize gluten meal, SBP and SPP were 0.955, 0.888, 0.823, 0.849, 0.860 and 0.856 respectively. Copyright © 2006 Society of Chemical Industry     

氨基酸折算法计算婴幼儿配方粉中乳清蛋白含量方法的评估

目的评价以氨基酸折算法计算婴幼儿配方粉中乳清蛋白含量的方法。方法本实验使用自配的流动相,采用酸水解氨基酸自动分析仪测定婴幼儿配方粉中氨基酸含量,再根据乳清蛋白中天冬氨酸/天冬酰胺、丙氨酸、苯丙氨酸和脯氨酸4种特征氨基酸含量的经验公式折算出婴幼儿配方粉中乳清蛋白占总蛋白的百分比。结果对我国市售多种品牌的婴幼儿配方粉中的水解氨基酸进行了检测,再计算出乳清蛋白含量,发现仅1阶段乳基婴儿配方粉基本符合大于60%的国标规定。结论该氨基酸折算法对婴幼儿配方粉中乳清蛋白含量的定量研究具有参考价值,但对掺有大豆蛋白的产品无法进行准确测定。     

Comparison of composition and antioxidant capacity of some cereals and pseudocereals

Polyphenols, phenolic acids, fibres and antioxidant capacity were determined in water, acetone and methanol extracts of buckwheat, rice, soybean, quinoa and 3 amaranth cultivars. Their antioxidant activities were comparatively assessed by total radical‐trapping antioxidative potential (TRAP), ferric ion‐reducing antioxidant power (FRAP), cupric‐reducing antioxidant capacity (CUPRAC) and nitric oxide (NO^?) assays, which comprised of contributions from polyphenols and phenolic acids (especially from the most abundant ferulic acid). The correlation coefficients between polyphenols and antioxidant activities of cereal and pseudocereal methanol extracts with FRAP, NO^?, CUPRAC and TRAP were 0.99, 0.97, 0.96 and 0.77, respectively. The weakest correlation was with dietary fibres, an average one exhibited with tannins and marked correlation was shown with the phenolics. All the applied methods have shown that pseudocereals have higher antioxidant activity than some cereals (rice and buckwheat) and can be successfully replaced by cereals in case of allergy.     

Protein and amino acids contents of Libyan dates at three stages of development

The protein and amino acid contents of three Libyan date varieties (Taasfirt, Bikrari and Khadhrai) at different stages of fruit development were determined. The protein concentration in all three varieties was highest at the green stage. Seventeen amino acids were detected and quantified; their concentrations (dry weight basis) were higher in Khadhrai and Bikrari than in Taasfirt. At the green stage the concentrations of glutamic acid, aspartic acid, lysine, leucine, alanine and serine were highest. At the yellow and ripe stages, glutamic acid, aspartic acid, lysine, leucine, proline and glycine were present in high concentrations. For most amino acids the concentrations were higher at the yellow stage than at the ripe stage. Copyright © 2004 Society of Chemical Industry     

不同产地桃胶中蛋白质和氨基酸的含量测定与营养价值评价

目的 建立桃胶中蛋白质和氨基酸的定量分析方法,并对不同产地桃胶的氨基酸营养价值进行评价。方法 利用凯氏定氮仪和氨基酸分析仪对不同产地桃胶的蛋白质和氨基酸进行定量检测,通过对氨基酸测定的前处理过程的优化,最终确定为:称取0.5 g桃胶、2 mL水进行除酸;对桃胶中的氨基酸进行含量、成分及组成比例的分析,并通过氨基酸比值系数法评价不同产地桃胶的营养价值。结果 5个产地桃胶的蛋白质含量为0.34～0.46 g/100 g,均包含15种氨基酸,总氨基酸(total amino acid, TAA)含量为0.22～0.29 g/100 g;必需氨基酸(essentialaminoacid,EAA)/TAA比值范围为31.9%～34.7%,EAA/非必需氨基酸(nonessential aminoacids,NEAA)比值范围为48.0%～53.1%,与世界卫生组织/联合国粮食及农业组织(WorldHealth Organization/Food and Agriculture Organization, WHO/FAO)提出的氨基酸理想模式较接近;氨基酸比值系数分(scoreofratiocoe...     

15种坚果果仁氨基酸组成及含量差异分析

目的分析15种市售坚果中氨基酸组成,比较不同品种坚果间必需氨基酸、非必需氨基酸含量的差异。方法使用氨基酸分析仪对样品中氨基酸的组成及含量进行分析,用最小显著性差异法(least-significant difference,LSD)进行多重比较。结果纸皮核桃中的必需氨基酸含量最高,为6.264 g/100 g,花生中总氨基酸含量最高,为22.622 g/100 g。使用模糊辨识法对贴近度进行计算得出,FAO/WHO模式蛋白质贴近度为0.840-0.933。结论坚果中必需氨基酸和总氨基酸含量的差异显著。限制氨基酸均为蛋氨酸和胱氨酸。东北松子的FAO/WHO模式蛋白质贴近度最高,最贴近人体所需蛋白质的模式。