Salt-Induced Disaggregation/Solubilization of Gliadin and Glutenin Proteins in Water

The effect of salt concentration used in preparing gluten, on the subsequent dissolution of gluten in water, was examined. Flour from a Canadian hard red spring wheat cultivar, Katepwa, was used to prepare glutens using three different solvents, i.e. distilled deionized water (DDW), 0·2% NaCl solution and 2% NaCl solution. The isolated wet glutens were extracted sequentially with DDW, providing four water soluble fractions and an insoluble residue. The amount of protein in each fraction was determined and respective compositions were assessed electrophoretically under reducing and non-reducing conditions. Surprisingly, DDW extracts of gluten prepared with 2% NaCl contained almost all the gliadins, except some ω-gliadin components, and most of the polymeric glutenin. For the gluten prepared with 0·2% NaCl, most of the gliadin, but only a small portion of glutenin, was extracted. For gluten prepared with DDW, only part of the gliadins and almost no glutenin was extractable with water. The DDW solubilities of gluten proteins prepared in DDW, 0·2% NaCl and 2% NaCl were 27, 52, and 85%, respectively, after four sequential extracts with DDW. The large increases in the solubility of gliadin and glutenin proteins in DDW when the gluten is prepared in salt solution (after removal of most of the salt) can be explained on the basis of a salt-induced conformational change of the proteins, which renders water a more effective solvent.     

离子束介导大豆DNA转入普通小麦后代的麦谷蛋白和醇溶蛋白分析

为了研究离子束介导大豆DNA转入普通小麦的效果,应用SDS-PAGE和A-PAGE电泳分析了离子注入介导大豆DNA转入普通小麦后代中高蛋白含量植株的麦谷蛋白和醇溶蛋白。SDS-PAGE电泳结果表明,与对照相比有8个高蛋白含量植株的HMW-GS谱带数目发生了变化或着色增强。A-PAGE电泳结果表明,与对照相比有9个高蛋白含量植株的醇溶蛋白谱带数目及着色强度发生了变化。说明离子束介导大豆DNA转入普通小麦后代中的高蛋白含量植株在醇溶蛋白和麦谷蛋白基因位点上可能出现了变异。     

利用近红外无损检测技术测定水稻土全氮含量的研究

探讨了利用近红外光谱法测定水稻土全氮含量的可行性,利用Nicolet公司生产的傅里叶变换近红外透射光谱仪测定129个水稻土样品的近红外光谱值,通过几种不同的光谱前处理,采用偏最小二乘回归(PLSR)法把测得的水稻土光谱值与实验室法测得的全氮数值拟合建立定标模型,经分析得出利用标准化处理的光谱数据与全氮含量之间建立的模型稳定性最好,模型相关参数为:预测标准差SEP=0.010 9,校正相关系数RCAL=0.98,内部交叉验证相关系数RVAL=0.86,校正标准差SEE=0.031 6。结果表明:近红外法测定结果与常规方法具有很好的相关性,可以快速、无损、准确地测定水稻土全氮含量。     

两种浊化剂在小麦谷蛋白大聚合体测定中的有效性

为比较两种浊化剂5-磺基水杨酸-无水硫酸钠（SSA-SS）和三氟乙酸（TCA）在比浊法测定小麦谷蛋白大聚合体（GMP）含量中的有效性,选用黄淮冬麦区有代表性的4个强筋小麦品种和4个中弱筋小麦品种组配的杂种F2代面粉为材料,采用1％DTT的50％正丙醇溶液提取GMP,分别用浊化剂SSA-SS和TCA浊化,再用酶标仪（波长540nm）连续（10～90min）测定不同基因型小麦的GMP提取液的吸光值。结果表明：（1）以SSA—SS为浊化剂时,牛血清蛋白浓度与吸光值的直线回归关系极其密切（r=0．9980）;以TCA为浊化剂时,牛血清蛋白浓度与吸光值的直线回归关系较差。（2）以SSA-SS为浊化荆时,各种基因型小麦GMP提取液的吸光值在30min内具有较好的稳定性;以TCA为浊化剂时,各种基因型小麦GMP提取液的吸光值随时间不断增加。说明比浊法测定小麦GMP含量时,以SSA-SS为浊化剂,加样振荡后10～30min内测定的结果最为稳定。     

ELISA法检测小麦粉中脱氧雪腐镰刀烯醇含量不确定度的分析

通过6种不同肥料在盆栽糯米香茶上的对比试验发现,在糯米香茶生长过程中,605高氮有机肥和配方601生物有机肥能较好地促进叶面积、叶绿素含量、光合作用和产量的提高,且随着收获次数的增加具有上升趋势。     

Depolymerisation and Re-polymerisation of Wheat Glutenin During Dough Processing. I. Relationships between Glutenin Macropolymer Content and Quality Parameters

The protein content and the content of protein-related parameters of both flour and dough were related to the maximum resistance (R_max) and extensibility (E) of dough, as determined in a Brabender Extensograph, and to loaf volume. The glutenin macropolymer (GMP) content of flour and dough was more strongly related toR_maxthan protein content or the content of the group of Osborne fractions (glutenin, gliadin, albumin/globulin). Within each group of protein-related parameters, the contents of the Osborne glutenin fractions explained the variation in all quality parameters better than the contents of the gliadin or albumin/globulin fraction. The GMP content of dough after 45 min rest was more strongly related toR_max, whereas the GMP content of flour was more strongly related toEand loaf volume. This demonstrates that, during mixing and resting of dough, changes occur in the GMP that are important forR_maxbut not forEor loaf volume. Although limited numbers of wheat cultivars (15), harvest years (2), flour blends (8) and resting times (3) were investigated, the relationship between the GMP content of dough andR_maxwas independent of these variables.     

小麦不溶性谷蛋白含量与HMW-GS及品质的关系

为了探索小麦不溶性谷蛋白(IG)含量与品质的关系,对176份不同筋力小麦材料的IG含量、HMW-GS组成类型和加工品质参数进行了检测及相关性分析。结果表明,供试材料的平均IG含量为2.44%,变化范围为1.25%～3.71%。共检测到10种HMW-GS亚基类型和16种亚基组合,其中,出现频率较高亚基类型是1(76.13%)、7+9(61.37%)、2+12(51.70%)和5+10(48.30%),出现频率较高亚基组合是1/7+9/2+12(25.57%)和1/7+9/5+10(22.16%)。亚基类型与IG含量显著相关,其中,优质亚基1、7+8和5+10比同位点的其他等位变异均显著增加IG含量,亚基组合1/7+8/5+10的IG含量最高,N/14+15/5+10的IG含量最低。IG含量与蛋白质含量、吸水率和稳定时间均呈显著正相关。IG含量可以作为小麦品质育种的快速有效检测指标。     

小麦谷蛋白大聚合体含量的影响因素

小麦籽籽谷蛋白大聚合体（ＧＭＰ）的含量反映了谷蛋白聚合体的粒度分布情况,其高低与其他烘烤品质性状有密切的关系。本文对其影响因素进行了研究。结果表明,ＧＭＰ含量受Ｇｌｕ－１位点等位基因变异、亚基相对含量和环境因素等的影响。其中,Ｇｌｕ－Ａ１ｂ和Ｇｌｕ－Ｄ１ｄ对ＧＭＰ含量有正效应,而Ｇｌｕ－Ａｌｃ和Ｇｌｕ－Ｄ１ａ对ＧＭＰ含量有负效应;Ａ组和Ｃ组亚基的相对含量分别与ＧＭＰ含量正相关和负相关。ＧＭＰ含量也     

应用RVA测定米粉淀粉成糊温度

淀粉的糊化温度是稻米淀粉品质的重要指标,决定淀粉在食品及工业上的用途,也与食用稻米的蒸煮品质密切相关。淀粉的糊化温度可以用淀粉谱仪（如快速淀粉黏滞性测定仪,Rapid Visco analyser,RVA）间接测定,但用淀粉谱仪测定的是淀粉的成糊温度（pasting temperature,PT）,它是指淀粉黏度刚开始升高时的温度。在许多情况下,从RVA配套软件 Thermocline for Windows中测定的PT是过高的。提出了两种能够用RVA较准确测定成糊温度的方法。一种是改变参数设置来“筛选”出能反映真正成糊温度的点;另一种是手工记录下淀粉黏度刚开始升高时的时间,利用公式(45/3.8)×(T1-1)+50 计算出稻米的成糊温度。利用手工计算出的成糊温度与通过差示扫描量热仪测定的最高糊化温度呈极显著正相关(r=0.97)。     

The Determination of Wheat Breadmaking Performance and Bread Dough Mixing Time by NIR Spectroscopy for High Speed Mixers

A non-invasive near infrared (NIR) technique has been used to identify changes in the development of bread dough during mixing. A Perten DA-7000 Diode Array NIR instrument with a fibre optic probe attachment was used. Both breadmaking and biscuit making varieties of wheat were examined. Doughs were mixed using a laboratory scale Chorleywood Bread Process (CBP) mixer and NIR spectra were gathered (one every 2 s). Flour quality data were used to determine the relationship between NIR and breadmaking quality attributes and to study varietal differences in breadmaking performance. Instrumental and sensory techniques were used to establish the important quality attributes of commercially and laboratory produced bread. NIR spectra and mixer torque were measured at different mixing times to obtain an overall picture of the mixing process from the initial hydration of the flour particles through optimum dough development until overmixing had occurred. Loaves were produced and assessed for volume by seed displacement and crumb structure using an image analysis technique. The dough elastic modulus was measured at a range of mixing times using a Bohlin VOR Rheometer. Comparison of results from the NIR spectra, dough properties and bread quality was carried out. Results revealed a relationship between the rheological properties of dough and the final quality parameters of bread. NIR was shown to have considerable merit in following dough changes during mixing which were related to final bread quality and thus has the potential to be used as an on-line method for controlling breadmaking mixers.     

Protein Content of Single Kernels of Wheat by Near-Infrared Reflectance Spectroscopy

Protein content is well known to affect the functional properties of processed wheat products. Traditionally performed on aliquots (0·25–2·2 g) from samples ranging in size from 30–40 g (for combustion and Kjeldahl analyses) to several hundred grams (for whole-grain near-infrared analysis), these methods inherently do not provide information on single-kernel protein variability. Inspection procedures by the United States Department of Agriculture for grading and classification of wheat are undergoing change to provide the processor or end user with information on the variability of several single-kernel properties including hardness, moisture, weight, and wheat class. The present study has focused on demonstrating the feasibility of measuring crude protein content of single wheat kernels by near-infrared reflectance. More than 300 commercial wheat samples from the 1992 U.S. harvest, representing five (hard red winter, hard red spring, soft red winter, hard white, and soft white) of the six (durum excluded) market classes were chosen, from which 10 kernels were randomly selected and handled on a single-kernel basis. Handling consisted of reflectance scanning (1100–2498 nm), drying (for moisture compensation), and combustion (for reference protein-content determination). Partial least squares and multiple linear regression models, when applied to samples excluded from calibration, demonstrated standard errors of performance ranging from 0·462 to 0·720% protein depending on the modeling technique, number of classes used to develop the model, and the wheat class tested. The pooling of wheat classes to produce a general model did not diminish model accuracy. Best results were achieved with an 1100–1400-nm region. Model performance worsened as the wavelength region widened or as the minimum wavelength shifted from 1100 nm to higher values.     

利用近红外透射光谱技术测定小麦品质性状的研究

为了研究小麦品质性状的快速测试方法，本试验以2002年来自全国各地的426个小麦品种为材料，利用近红外光谱透射仪(NITS)分析了小麦籽粒水分、蛋白质含量、硬度和面粉的干、湿面筋含量、灰分含量、SDS及Zeleny沉淀值等8项指标，根据定标集样品化学分析数据和吸收光谱建立了定标模型，并获得了较高的预测集决定系数(O．70～O．97)和较低的标准误差(O.05～11．18)。同时，选用了一批有代表性的预测集样品对模型进行了预测，结果表明，近红外光谱技术用于测试小麦品质是可行的，能够用于育种的早代选择。     

Folate Content and Chemical Composition of Commercially Available Gluten-Free Flour Alternatives

Plant Foods for Human Nutrition - Concerns about the nutritional and sensory qualities of gluten-free (GF) products has generated interest in the evaluation of novel gluten-free ingredients. Folate...     

Size Characterisation of Glutenin Polymers by HPSEC-MALLS

The use of an on-line coupling of a new high-performance size exclusion chromatography (HPSEC) phase characterised by a very high exclusion limit and a multiangle laser light scattering detection (MALLS) for the size characterisation of wheat glutenin polymer was examined. Flour glutenin polymers which were extracted and purified by differential solubility in aqueous 50 and 70% propan-1-ol were solubilised with or without sonication in combination with a surfactant, 2% SDS. The glutenin polymers of the two genotypes studied, Soissons (5+10, Glu-1D) and Thésée (2+12, Glu-1D), were characterised by large polydispersity and by significant differences of size distribution of total polymers. The molecular size distribution of the total polymers, which can be used to differentiate the two genotypes, was highly correlated with the percentage of high-molecular glutenin subunits (HMW-GS) in glutenins. Furthermore, the results obtained for both the SDS-soluble and SDS-insoluble glutenin polymers from the two varieties revealed significant differences in size distribution, and also in molecular conformation (dependence of size upon mass). The molecular dimensions of SDS-insoluble polymers increased more slowly with the molecular weight than SDS-soluble polymers, which suggested a more compact structure. To conclude, the method appears to be a viable procedure to obtain rapid size characterisation of unreduced glutenin.     

玉米子粒颜色对近红外模型预测其淀粉含量的影响

以我国黑龙江、吉林、辽宁、内蒙古、山西、广西等省区368份玉米样品为材料,分别采用近红外透射光谱(NITS)和实验室常规分析(LAB)测定其淀粉含量,通过校正样品集建立样品吸收光谱与化学成分间的关系模型,校正并优化原有神经网络模型。经检验,校正模型Ⅰ(黄色样品)、校正模型Ⅱ(橙红色样品)和校正模型Ⅲ(总样品)的预测平均残差(Bias)依次为0.15、0.05和1.04;均方误差(RMSE)依次为1.06、1.07和1.12。预测效果相比较,模型Ⅰ和模型Ⅱ预测值与常规分析值的残差和均方误差均低于模型Ⅲ,因此对玉米整子粒淀粉近红外分析,按样品外观颜色分类定标(校正)更有利于提高模型的预测性能。     

利用近红外反射光谱技术测定稻米中脂肪含量的研究初报

利用精米粉脂肪含量化学分析值及其近红外反射光谱以建立分析精米中脂肪含量数学模型。选取3段谱区（6100～4250 cm-1;6100～5450 cm-1并4600～4250 cm-1;7500～5450 cm-1并4600～4250 cm-1）分别采用4种不同的预处理方法（直线扣除、乘性散射校正、矢量归一、一阶导数）,对其结果进行比较,发现选择不同谱区和不同光谱预处理方法对所建模型有很大的影响,同时证明了利用近红外光谱技术测定稻米脂肪含量的可行性。还阐述了如何对模型进行评价,并讨论了它在遗传育种中的应用。     

近红外光谱法快速测定苎麻果胶含量的研究与探讨

本文旨在探讨应用近红外光谱法快速测定苎麻中果胶含量的可行性.对62个苎麻样品进行近红外光谱扫描及果胶含量的测定,采用偏最小二乘法(PLS)建立近红外光谱信息与果胶含量的校正模型,该模型的相关系数为0.904.利用该模型对16个验证集样品进行果胶含量的预测,预测标准差为0.21.结果表明,该方法用于快速测定苎麻果胶含量是可行的.     

一对HMW-GS近等基因系面粉品质、 面团流变学和烘烤品质的研究

对龙麦15(1,7+8,2+12)和新龙麦15(1,7+8,5+10)这对高分子量(HMW)麦谷蛋白亚基近等基因系进行了品质分析。结果表明含5+10 亚基的新龙麦15在蛋白质含量、干面筋、粉质仪测得的吸水率和拉伸仪测得的延伸性方面与含2+12亚基的龙麦15是相同的。在两者的籽粒蛋白质含量均为13.5%（干基）时,含5+10亚基的新龙麦15比含2+12亚基的龙麦15在Zeleny沉降值、稳定时间、最大抗延阻力和面包体积上分别高10%、60%、50%和50 ml;在湿面筋和形成时间上含5+10亚基的龙麦15略低于含2+12 亚基的龙麦15。