食品中色氨酸测定的简单方法

本文叙述了一个测定食品中色氨酸的非常简单而且灵敏的方法。食品蛋白质经木瓜酶部分水解后,被完全溶解,色氨酸用8M的尿素稀释,直接测量荧光。激发波长288nm,发射波长348nm,色氨酸用     

方格星虫氨基酸含量测定及其营养价值评定

将鲜方格星虫和干方格星虫用酸水解后使用全自动氨基酸分析仪对氨基酸种类及含量进行测定,并对其营养价值进行评定。结果表明,方格星虫样品中含有18种氨基酸,鲜方格星虫谷氨酸和天门冬氨酸含量较高,分别为3.48%和2.02%,胱氨酸(0.21%)和色氨酸(0.21%)含量较低;干方格星虫中谷氨酸(11.89%)和精氨酸(7.94%)含量较高,胱氨酸(0.45%)和色氨酸(1.07%)含量较低。根据FAO/WHO理想模式评定标准,方格星虫干样品中的氨基酸均达到优质蛋白源标准,鲜方格星虫样品中的氨基酸大部分达到优质蛋白源标准。     

加工淀粉后的玉米渣是丰富的蛋白源

苏联之所以能顺利实现食品生产纲要,与在很大程度上合理利用植物资源分不开的。特别注意植物原料加工废料和付产品的利用。生产玉米淀粉后的付产物——用压榨法制取玉米胚油后的胚渣、麸质、液态浸出物等都属于这一类。上述废料是很有潜力的蛋白质原料,但还没有用其制取食用蛋白质。所以,用其制取食品蛋白是大有可为的。因为从生物学效价看,玉米胚蛋白质可与牛肉和鸡蛋媲美;所以在研究食品生产纲要时,对玉米胚渣的研究与对胚加工品的研究同等对待。用韦尔赫涅德涅普罗夫斯克淀粉—糖密联合企业的经第一、二次压榨后的玉米胚渣作为研究样。测定其化学成分的常用方法是:用标准法测定含水量,凯氏法测定总氮,以系数6.25乘氮含有量的方法测定“粗”蛋白质,鲁什科夫斯基法测“粗”脂肪,艾维尔斯法测定淀粉;别尔特兰法测定糖——总糖和还原糖,丘什涅尔和卡涅克法测定纤维素,耶尔马科夫法测定灰分含有量,根据奥斯波尔恩采用А.И耶尔马科夫的诱变法测定蛋白质组分,以在110℃情况下,用6NHCl 使盛入外接管中的蛋白质酸水解24小时后,用捷克斯洛伐克产的AAA—881型氨基酸分析仪测氨基酸成分。单独准确称取一试样,经硷水解后,用带有 N—二甲胺基苯甲醛的显色反应法测定色氨酸。把必需氨基酸的氨基酸数值换算为联合国粮农卫生组织提出的理想蛋白质中氨基酸含有量的百分数。就某些指标看,玉米胚渣的化学成分与分离出胚制品中的大不相同。因此,在其“粗”蛋白质、淀粉、纤维素含量增加的同时。胚渣里的“粗”脂肪、总糖,灰分和水分含有量减少。特别是经第二次压榨后,胚渣里的化学     

4种植物油热氧化同步荧光光谱分析

以亚麻籽油、大豆油、菜籽油与葵花籽油为原料,在不同温度条件下氧化并测定其不同时间的同步荧光光谱,分析同步荧光光谱及荧光物质变化情况。结果表明,4种植物油不同温度下的同步荧光光谱峰变化主要集中在300~415 nm内,且随着加热时间的延长存在波动现象;在50℃和150℃加热氧化条件下,300,330,375,415 nm这4个峰都存在明显的波动现象;二维相关分析表明,这4个峰的荧光强度变化速率不同,不同油变化差异较大;同种油在不同温度下,4个峰的波动情况、相互关系、变化速率均有明显差异。这些峰的变化与油脂氧化过程中荧光物质和油脂氧化程度的变化有关,可以利用同步荧光光谱的变化特性作为监控油脂氧化的依据。     

近红外光谱法快速测定海产品处理过程中牛磺酸含量的研究

利用近红外光谱分析技术,建立快速检测水产品下脚料提取过程中牛磺酸含量的方法。利用氨基酸分析仪测定样品中牛磺酸含量,采用一阶导数对原始光谱进行处理,采用偏最小二乘法建立校正模型,并预测样品中牛磺酸含量。所建模型回归系数(R2)为99.12%,交叉检验均方根为0.086;经验证,预测值与参考值的回归系数(R2)为99.9%,预测误差均方根为0.040,模型预测值与氨基酸分析仪测定值之间没有显著差异。因此,近红外光谱分析法可以检测水产品下脚料提取过程中牛磺酸含量。     

近红外光谱法测定大米中的淀粉含量

用化学方法测定64个大米样品中的淀粉含量,利用近红外谷物分析仪采集样品的近红外光谱,选择合适的光谱区间和光谱预处理方法。50个定标集样品的近红外光谱经二阶导数及标准多元离散校正(Standard MSC)预处理,结合偏最小二乘法(PLS)建立了大米中的淀粉含量测定的定标模型,其相关系数为0.8780。14个验证集样品用于外部检验,大米中的淀粉含量的模型预测值与化学值之间的相关系数为0.9498。     

茚三酮比色法测定牛肉中游离氨基酸的试验研究

制用茚三酮比色法测定出牛肉中游离氨基酸含量.对游离氨基酸的提取方法及测定体系的pH、最大吸收波长、反应时间、显色剂用量等进行了研究,并提出了最佳提取方法为蒸馏水煮制提取法,得出最佳的测定条件为pH值为6.8,沸水浴加热15 min并冷却15 min后加入KIO3稀释液,在最大吸收波长为568 nm处进行测定.     

用生理体液法测定茶叶中的游离氨基酸

本文采用了笔者改编的生理体液程序〔《氮基酸杂志》1987(4)〕和茶氨酸专用程序〔第六次全国色谱学术论文集(下)1987.10〕,对同一茶叶样品中的游离氨基酸进行了比较测定,同时对四个不同类型的茶鲜叶检测出28种氨基酸。茶叶中游离氨基酸含量占干重2—5％,由于它与茶叶的滋味,茶叶的药理作用及营养辅助作用密切相关,所以在茶叶品质鉴定以及茶树品种特性鉴别中乃是一个重要的理化指标。笔者采用生理体液改进程序,在日立835—50型氨基酸自动分析仪上对茶叶中的游离氨基酸进行了质量测定,效果良好。     

柴胡根部中氨基酸含量的测定及分析

旨在了解柴胡的营养价值与保健药用功效。以11种柴胡的干燥根为试验材料,利用L-8900型氨基酸分析仪测定其氨基酸的组成及含量并进行分析。结果表明,供试材料含有17种氨基酸,种类较齐全。其中包含人体必需氨基酸7种,儿童必需氨基酸2种,各类味觉氨基酸等,色氨酸由于在酸水解过程中被破坏,未进行测定。这11种柴胡的氨基酸的E/N值在0.291~0.510;E/T值在22.5%~33.8%,接近理想蛋白质的要求;RAA及RC的数值大都接近于1,SRC的数值都在80以上,接近100。根据FAO/WHO修订的人体必需氨基酸含量模式谱,这11种柴胡根部必须氨基酸占氨基酸的比例大部分符合该谱,只有亮氨酸、苯丙氨酸+酪氨酸中度缺乏。     

向日葵籽仁脂肪和脂肪酸含量近红外光谱模型的建立

为实现向日葵品质的快速无损检测,选取50份具有代表性的油用向日葵材料,采用偏最小二乘法（PLS）构建籽仁脂肪、亚油酸、油酸、硬脂酸和棕榈酸含量的近红外光谱（NIRS）模型。结果表明,脂肪、亚油酸、油酸含量模型校正和验证相关系数均大于0.96,且预测值与化学值相对误差均在10%以下,能够达到样品成分含量的快速测定。硬脂酸和棕榈酸含量模型校正相关系数分别为0.92和0.82,验证相关系数分别为0.83和0.74,预测值与化学值相对误差在4.66%~17.99%之间,可用于样品成分含量的初步预测。本研究构建的NIRS模型,有助于油用向日葵种质资源品质鉴定和快速筛选。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.