Xylanase Induced Changes to Water- and Alkali-Extractable Arabinoxylans in Wheat Flour: Their Role in Lowering Batter Viscosity

The effect on the viscosity of wheat flour batter following treatments with a crude pentosanase-containing enzyme preparation and an endo-xylanase purified from the same preparation, was studied in relation to changes to the chemical features of the water- and Ba(OH)₂-extractable arabinoxylan fractions. Addition to batter of the crude enzyme or the pure xylanase caused a consistent and identical decrease in batter viscosity, demonstrating that the viscosity change was caused by the selective action of the xylanase in the crude enzyme preparation. The lowering of batter viscosity upon addition of enzyme was attributed to partial hydrolysis of the arabinoxylans in the water-extractable fraction which lead to an increase in the proportion of lower molecular weight water-extractable arabinoxylans possessing an increased xylose/arabinose ratio. There was no detectable change in the monosaccharide composition of either the water- or Ba(OH)₂-extractable arabinoxylan fraction after enzyme treatment and no indication of any increase in the amount of the water-extractable arabinoxylan fraction at the expense of the Ba(OH)₂-extractable fraction. It is concluded that the xylanase can extensively degrade arabinoxylan to small oligosaccharides in vitro. However, such degradation does not take place in situ, in the enzyme treated batters, where only a very small shift in the molecular weight profile of the water-extractable arabinoxylans was necessary to effect major changes to batter viscosity.     

Physicochemical, Structural and Textural Properties of Tortillas from Extruded Instant Corn Flour Supplemented with Various Types of Corn Lipids

The chemical composition and the components of corn grain affect the quality of tortillas produced from extruded instant corn flour (EICF). We have studied the effects of various types of corn lipids added at several concentrations to the regular raw corn flour before processing. The structural properties of flour, the effective moisture diffusion coefficient and the weight loss during cooking of fresh masa, as well as the textural characteristics of tortillas were analysed as a function of concentration and type of corn lipid added. The concentration of added lipid ranged from 0·5 to 2% (w/w). Each type and concentration of lipid was observed to have a different effect in the quality of masas and tortillas. Commercially it is desired to have tortillas with good properties and a high yield, that is, optimum weight transformation from corn to tortilla. From our analysis, the lowest dehydration rate (lowest effective moisture diffusion coefficient) and the best physicochemical and textural characteristics of fresh masas and tortillas were obtained from flour supplemented with 0·5% (w/w) of the nonpolar lipid fraction III. The loss in starch crystallinity due to the cooking process of masa into tortilla was similar in all treatments.     

Effect of High-Energy Milling on Bioactive Compounds and Antioxidant Capacity in Nixtamalized Creole Corn Flours

Plant Foods for Human Nutrition - This study aimed at evaluating the effect of high-energy milling (HEM) and traditional nixtamalization (TN) on bioactive compounds and antioxidant capacity in...     

小麦不同生育时期木聚糖酶活性及木聚糖酶抑制蛋白活性的变化

为给小麦抑制蛋白的分离纯化以及表达研究提供信息,以小麦品种兰考矮早八和豫麦49为材料,检测和分析了小麦在不同生育时期叶片和籽粒木聚糖酶活性及木聚糖酶抑制蛋白活性的动态变化.结果表明,木聚糖酶活性及木聚糖酶抑制蛋白活性在两个品种间没有差异,不同生育时期小麦叶片及籽粒木聚糖酶活性没有显著变化,可能以基础水平存在.叶片中的木聚糖酶抑制蛋白活性自苗期开始,经拔节期到抽穗期,总体呈现增加趋势,但进入灌浆～成熟期则显著下降,而籽粒中的木聚糖酶抑制蛋白活性则随籽粒的成熟持续升高.     

纳米材料处理水对糯玉米生长及其生理变化的影响

用纳米材料处理水浸种和浇灌糯玉米,研究对糯玉米发芽势和生长及生理变化的影响。结果表明,纳米材料处理水浸种后在2 d内显著地提高了糯玉米种子的发芽势;处理水浇灌糯玉米,促进了作物对水分的吸收,增加了植株的生物量,提高了叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活性,降低了丙二醛(MDA)的含量,增强了糯玉米的抗性。     

小麦粉贮存过程中HMW-GS变化研究初报

为了了解小麦粉贮藏过程中高分子量麦谷蛋白亚基(HMW-GS)变化情况，本文作者利用含优质亚基1，5，7，9，10的小麦品种烟97L181研究其后熟过程中HMW-GS的变化。结果表明，同一时间所提样品中各亚基在灌浆成熟过程中所占比例没有明显变化，贮存前5亚基含量最高，占HMW-GS总含量的35％左右，其次为10亚基，约占24％；贮存后亚基10、亚基7含量较高，分别占到总量的29％、28％。贮存前后亚基比例有明显变化，5亚基在总亚基中比例下降约15个百分点，分子量较高的7亚基占总亚基比例上升了约12个百分点。     

Effects of Starch Gelatinisation on the Thermal,Dielectric and Rheological Properties of Extruded Corn Masa

The effects of processing on starch gelatinisation of corn masa prepared by extrusion were monitored by observing the changes in thermal diffusivity, starch crystallinity, peak viscosity and the differential dissipation factor (DDF). The results show that there is a threshold processing temperature (Tc), about 80 °C, above and below which different behaviour patterns for the measured properties are observed. The thermal diffusivity, starch crystallinity and the position of a peak in the DDF have a maximum at approximately Tc=80 °C. The peak viscosity decreases monotonically for Tc up to 80 °C and then remains constant. On the bases of textural characteristics of masa and tortilla, this work indicates that the degree of starch gelatinisation in the extruded masa is optimum at temperatures at approximately 80 °C where the room temperature thermal diffusivity and differential dissipation factors have maximum values. Textural analysis made in tortillas with masas prepared at various temperatures support the above conclusions.     

不同品质类型小麦阿拉伯木聚糖流变性质的研究

为了解阿拉伯木聚糖流变性质及其与小麦品质的关系,对不同品质类型的小麦（强筋、弱筋）阿拉伯木聚糖(简称WEAX)的零剪切黏度（η0）及酶促氧化胶凝能力等指标进行了研究。结果表明,不同品质类型小麦间WEAX溶液的黏度特性存在一定差异,零剪切黏度值（η0）变幅为0.20～56.50 Pa·s,大部分集中在0.20～2.43 Pa·s,个别品种（中优206、烟农19）数值偏差较大。在过氧化物酶体系(POX/H2O2)作用下,WEAX凝胶特性（G′、G″值）差异显著,强筋与弱筋小麦中均存在胶凝能力或强或弱的品种,说明WEAX的上述流变特性与小麦筋力（或硬度）无直接关系。     

由2015年美国玉米高产竞赛结果探讨美国玉米育种

从产量、品种等方面介绍2015年美国玉米高产竞赛结果,深入解析取得优胜的玉米品种,探讨近5年来美国玉米高产品种的变化及10年间美国玉米高产竞赛与玉米单产水平的变化趋势,强调品种选育在玉米增产中的关键作用。     

硬质小麦籽粒阿拉伯木聚糖含量的遗传变异研究

为了更好地理解环境和基因型对小麦阿拉伯木聚糖含量的影响,为小麦品质改良提供科学依据,采用比色法测定了美国西部51个硬质小麦品种的阿拉伯木聚糖组分含量,这些小麦品种包括冬小麦和春小麦,分别被种植在3个不同的地点.结果表明,参试冬小麦品种水溶性和总阿拉伯木聚糖含量的变异范围分别为0.39%～0.81%和3.09%～4.04%,春小麦品种这两种木聚糖含量范围分别为0.48%～0.92%和3.94%～4.70%.小麦籽粒阿拉伯木聚糖含量的变异同时受品种、环境及其互作效应的显著影响,环境效应太于品种效应.小麦品种间阿拉伯木聚糖含量的变异主要表现在水溶性组分上.就不同组分而言,基因型对水溶性阿拉伯木聚糖组分的影响相对较大,环境则分别对冬小麦水不溶性、春小麦水溶性阿拉伯木聚糖组分有较大的影响.品种间和环境间阿拉伯木聚糖含量的变异,冬小麦大于春小麦;水溶性阿拉伯木聚糖含量的遗传型方差春小麦大于冬小麦.冬、春小麦的水溶性阿拉伯木聚糖含量的广义遗传力均大于95%,通过遗传育种的方法改良小麦阿拉伯木聚糖含量是可行的.冬小麦与春小麦阿拉伯木聚糖含量的平均值之间无明显差异.     

Biochemical and Molecular Study of the Influence of Amaranthus hypochondriacus Flour on Serum and Liver Lipids in Rats Treated with Ethanol

Hyperlipidemia and hepatic steatosis are frequent alterations due to alcohol abuse. Amaranth is a pseudocereal with hypolipidemic potential among other nutraceutical actions. Here we study the effect of Amaranthus hypochondriacus (Ah) seeds on serum and liver lipids, and the expression of genes associated to lipid metabolism and liver histology in male Wistar rats intoxicated with ethanol. The animals were divided into four groups; two groups were fed the American Institute of Nutrition 1993 for maintenance diet (AIN-93M), and the other two with AIN-93M containing Ah as protein source. One of each protein group received 20 % ethanol in the drinking water, thus obtaining: CC (control casein), EC (ethanol casein), CAh (control Ah) and EAh (ethanol Ah). When comparing EAh vs. EC, we found a positive effect of Ah on lipids, preventing the increment of serum cholesterol (p?<?0.001), through the higher expression of the LDL receptor (p?<?0.001); and it also decreased free (p?<?0.05) and esterified cholesterol (p?<?0.01) in liver, probably via the reduction of the 3-hydroxy-3-methylglutaryl coenzyme A reductase expression (p?<?0.001). We also observed that amaranth contributed to the decrease of fat deposits in liver, probably through the decrease in acetyl-CoA carboxylase alpha (p?<?0.01), glycerol-3-phosphate acyltransferase 1 (p?<?0.01) and diacylglycerol O-acyltransferase 2 (p?<?0.05) expression. The histological study showed a decrease in the fat deposits in the amaranth group when compared to casein; this is consistent with the biochemical and molecular parameters studied in this work. In conclusion, amaranth could be recommended to avoid the alterations in the lipid metabolism induced by alcohol and other harmful agents.     

Oil Oxidation in Corn Flour from Grains Processed with Alkaline Cooking by Use of Peroxide Value, UV and FTIR

The objective of this work was to evaluate the effect of alkaline cooking on the oxidative stability of oil in corn flour. A central composite design was used to study the combined effect of lime concentration (%) and steep time (h) on peroxide value (PV); specific extinction coefficients at 232 and 270 nm (K₂₃₂ and K₂₇₀); and FTIR absorbance at 3009 cm^?1, 3444 cm^?1, and 3530 cm^?1 in oils from corn flour obtained by alkaline cooking. The results indicate that lime concentration and steep time affected the PV, K₂₃₂, and K₂₇₀. A decrease of 2.56 % was observed in the IR absorption bands, corresponding to the polyunsaturated fatty acids. The FTIR spectra also showed absorption bands related to the secondary oil oxidation products.     

Identification of Dynamic Changes in Proteins Associated with the Cellular Cytoskeleton after Exposure to Okadaic Acid

Exposure of cells to the diarrhetic shellfish poison, okadaic acid, leads to a dramatic reorganization of cytoskeletal architecture and loss of cell-cell contact. When cells are exposed to high concentrations of okadaic acid (100–500 nM), the morphological rearrangement is followed by apoptotic cell death. Okadaic acid inhibits the broad acting Ser/Thr protein phosphatases 1 and 2A, which results in hyperphosphorylation of a large number of proteins. Some of these hyperphosphorylated proteins are most likely key players in the reorganization of the cell morphology induced by okadaic acid. We wanted to identify these phosphoproteins and searched for them in the cellular lipid rafts, which have been found to contain proteins that regulate cytoskeletal dynamics and cell adhesion. By using stable isotope labeling by amino acids in cell culture cells treated with okadaic acid (400 nM) could be combined with control cells before the isolation of lipid rafts. Protein phosphorylation events and translocations induced by okadaic acid were identified by mass spectrometry. Okadaic acid was shown to regulate the phosphorylation status and location of proteins associated with the actin cytoskeleton, microtubules and cell adhesion structures. A large number of these okadaic acid-regulated proteins have previously also been shown to be similarly regulated prior to cell proliferation and migration. Our results suggest that okadaic acid activates general cell signaling pathways that induce breakdown of the cortical actin cytoskeleton and cell detachment.     

微胚乳超高油玉米种子萌发过程中子粒脂类化合物含量变化研究

对微胚乳超高油玉米种子萌发过程中子粒脂类化合物含量的生理生化及显微化学变化进行了研究。结果表明,微胚乳超高油玉米种子在萌发过程中,子粒质量在第1天没有变化,从第2天开始减小。子粒含油率在前3天变化不大,第4天开始减少,但每克种子绝对含油量在第3天开始下降,油分消耗速率最快的是第6天。种子酸价在种子萌发前4天均比干种子低,第5天开始上升,上升速率最快的是第7天。子粒油分的显微化学变化表明,种子油分消耗是在第3天开始的,到第7天时油分基本消耗殆尽。     

种子包衣对微胚乳玉米种子发芽过程中生理生化变化的影响

研究了种子包衣对微胚乳玉米种子萌发时生理生化变化的影响。结果表明：微胚乳玉米种衣剂(MESC)包衣可提高种子萌动时赤霉素(GA₃)与脱落酸(ABA)含量的比例,提高种子生长素(IAA)和可溶性总糖的含量,促进蛋白质的形成和油脂的降解,加速氨基酸的利用。适乐时种衣剂(FDXN)包衣提高了ABA的含量,降低可溶性总糖含量,减缓油脂的降解和氨基酸的利用,最终抑制种子的发芽。微胚乳玉米种衣剂包衣可促进微胚乳玉米种子发芽过程中的生化变化过程,从而促进种子发芽。     

玉米灌溉田土壤水分变化及其耗水规律研究

以辽宁省主要旱地作物玉米为研究对象,研究了其灌溉田土壤水分变化及其耗水规律。在试验条件下,0～20 cm土层水分含量最低,整个玉米生育期内水分变化幅度最大;30～50 cm土层由于受长期耕作习惯等因素的影响土壤的黏滞度较高,保持较明显的水分梯度,并使50～90 cm土层水分变化与0～20 cm土层相比滞后1～3 d;90～120 cm土层土壤水分受根系影响较小,变化不大。玉米生育前期农田实际蒸散量和参考蒸散量均趋于不断增大,生育中期个别时段内由于受阴雨气候影响蒸散量有所减弱;参考蒸散量最大值出现在玉米播种后第46天左右,农田实际蒸散量最大值出现在玉米出苗后第96天左右,玉米生育后期两者逐渐减弱。玉米生育前期表层土壤棵间蒸发量占实际蒸散量的比重较大,生育中期棵间蒸发量受降雨和灌溉等因素影响,变化幅度较大,生育后期相对较小。随着玉米叶面积增加,作物系数不断增加,在播种后第81天左右作物系数达最大值,之后作物系数逐渐下降。     

稻瘟病菌Rab5蛋白的表达及互作蛋白的初步筛选

Rab5是Rab蛋白家族成员之一,它主要负责调控胞吞作用中囊泡与早期内含体的融合。通过构建MoRab5的原核表达载体,成功诱导了pET-28a-MoRab5融合蛋白的表达,并获得了纯化蛋白,通过His Pulldown检测到一些可能与Rab5互作的蛋白。     

Kinetic Approach to the Influence of Chia Flour on Glucose Bioaccessibility from Hydrothermally Treated Maize and Quinoa Starch

Plant Foods for Human Nutrition - Starch structure and bioactive ingredients play an implicit role in the control of glucose release at intestinal level reducing the risk of inadequate metabolic...