Fractionation and reconstitution experiments provide insight into the role of starch gelatinization and pasting properties in pasta quality

Commercial durum wheat semolina was fractionated into protein, starch, water-extractable, and sludge fractions. The starch fraction was hydroxypropylated, annealed, or cross-linked to change its gelatinization and pasting properties. Spaghettis were made by reconstitution of the fractions, and their quality was assessed. Hydroxypropylated starches were detrimental for cooked pasta quality. Cross-linked starches made the reconstituted pasta firmer and even brittle when the degree of cross-linking was too high. These results indicate that starch properties play a role in pasta quality, although the gluten remains very important as an ultrastructure agent. It was concluded that, given a certain gluten ultrastructure, starch water uptake and gel properties and/or its interference with or breakdown of the continuous gluten network during cooking determine pasta quality.     

Fractionation-reconstitution experiments provide insight into the role of endoxylanases in bread-making.

The impact mechanism of endoxylanases in straight dough bread-making was investigated in fractionation-reconstitution experiments. To this end, two European flours with different bread-making characteristics were separated in gluten, prime starch, a squeegee fraction (SQF), and a water-extractable fraction. Whereas the former fractions contained negligible levels of arabinoxylan (AX), the latter contained, respectively, most of the water-unextractable AX (WU-AX) and all of the water-extractable AX (WE-AX). In vitro modification with a Bacillus subtilis endoxylanase allowed controlled solubilization of WU-AX from SQF and controlled degradation of solubilized AX and WE-AX from the water-extractables. It followed from bread-making tests with the reconstituted flours that endoxylanases exert positive loaf volume effects in bread-making by lowering the concentration of WU-AX and increasing that of total soluble AX. Limited degradation of WE-AX and significant breakdown of solubilized AX by endoxylanases, on the other hand, resulted in volume losses when compared to their nondegraded counterparts. The volume increasing effects of endoxylanases are therefore related to their ratio of solubilizing to degrading activity and thus to their substrate specificity.     

氮磷互作对弱筋小麦氮素利用与籽粒淀粉品质的影响

为了解氮磷对弱筋小麦品种氮素利用效率及籽粒淀粉品质的影响,以宁麦13为材料,在施氮120kg/hm2(N1)、180 kg/hm2(N2)水平下,分别设置3个磷素水平(施P2O5水平为P1:60 kg/hm2,P2:120 kg/hm2,P3:180 kg/hm2),分析氮磷素对弱筋小麦植株氮素吸收利用、籽粒淀粉粒度分...     

Durum wheat (Triticum durum Desf.) Mediterranean landraces as sources of variability for allelic combinations at Glu-1/Glu-3 loci affecting gluten strength and pasta cooking quality

With the aim of identifying durum wheat landraces (LR) with a potential use in breeding programs for gluten strength enhancement, the allelic combinations present at five glutenin loci were determined in a collection of 155 LR from 21 Mediterranean countries. A set of 18 modern cultivars (MC) was used for comparison. Gluten strength was determined by SDS-sedimentation test on grain samples from field experiments conducted during 3 years. A total number of 131 different allelic/banding pattern combinations were found. Taking together high (HMW-) and low (LMW-) molecular weight glutenin subunit loci resulted in 126 combinations in LR, but only nine in MC, which are characterized for having strong gluten. Two LMW-2 type models were identified in the collection and LMW-1 types were absent. LMW-2 was present in 78 % of MC, including the only three with outstanding gluten strength (Ocotillo, Claudio and Meridiano), while 14 % of the LR had LMW-2 and 6 % LMW-2^?. In the LR a known combination LMW-2 (aaa) and three new ones had a positive effect on the gluten strength. LMW-2 models were found in high frequency in LR from Italy and the three Maghreb countries; from medium to low frequencies in genotypes from Turkey, Jordan, Lebanon, Portugal and Spain, and were absent in the remaining countries. The large variability found in LR proved their potential value in breeding to broaden the genetic basis of gluten quality improvement. Genotypes interesting for breeding purposes are identified.     

Identification of the taste enhancer alapyridaine in beef broth and evaluation of its sensory impact by taste reconstitution experiments

An essential compound imparting the sweet taste to beef broth was investigated. Taste activity-guided fractionation of beef broth by ultrafiltration, gel permeation chromatography, and HPLC in combination with the recently developed comparative taste dilution analysis enabled the localization of a fraction possessing sweetness-enhancing activity upon degustation. Comparison of the chromatographic, spectroscopic, and sensory data with those of the synthetic reference compound led to the identification of the sweetness-enhancing N-(1-carboxyethyl)-6-(hydroxymethyl)pyridinium-3-ol inner salt, named alapyridaine, which was recently isolated from heated aqueous solutions of hexoses and l-alanine. After quantification of alapyridaine in beef broth, sensory analysis of synthetic beef taste recombinates spiked with synthetic alapyridaine in its "natural" concentration of 419 mug/L and comparison to the taste quality of a tastant recombinate lacking the alapyridaine revealed a significant increase in sweetness and umami character only when the alapyridaine was present in the recombinate. These data demonstrate for the first time that, in "natural" concentrations, the alapyridaine exhibited a pronounced effect on the overall taste quality of beef broth, in particular, on the sweet and umami character.     

钾对强筋小麦产量和品质的调控效应

采用盆栽试验方法研究了钾对强筋小麦产量和品质的影响。结果表明，施用钾肥能增加小麦株高、穗长、千粒重及穗粒数，因而显著提高小麦产量，小麦增产10．2％～24．8％。施用钾肥能提高小麦籽粒蛋白质含量和湿面筋含量，但对籽粒沉降值的影响不大。     

Assignments of proton populations in dough and bread using NMR relaxometry of starch, gluten, and flour model systems

Starch-water, gluten-water, and flour-water model systems as well as straight-dough bread were investigated with (1)H NMR relaxometry using free induction decay and Carr-Purcell-Meiboom-Gill pulse sequences. Depending on the degree of interaction between polymers and water, different proton populations could be distinguished. The starch protons in the starch-water model gain mobility owing to amylopectin crystal melting, granule swelling, and amylose leaching, whereas water protons lose mobility due to increased interaction with starch polymers. Heating of the gluten-water sample induces no pronounced changes in proton distributions. Heating changes the proton distributions of the flour-water and starch-water models in a similar way, implying that the changes are primarily attributable to starch gelatinization. Proton distributions of the heated flour-water model system and those of fresh bread crumb are very similar. This allows identifying the different proton populations in bread on the basis of the results from the model systems.     

肥密互作对强筋春小麦品质的影响

针对某些地区小麦生产中存在的加大种植密度和增加施肥量问题,以优质春小麦品种“龙麦26”为材料,设置施肥量与密度互作试验,分析其对高寒地区强筋春小麦品质形成的影响。结果表明,种植密度和施肥量对小麦子粒品质和面粉品质的影响不具交互效应,但施肥量和种植密度对小麦千粒重和子粒容重的影响显著。稀植可提高千粒重,但降低了子粒容重,较高的施肥量降低了子粒容重和千粒重;适宜的施肥量可提高子粒中蛋白质的百分含量和湿面筋含量,同时获得较高的沉淀值和降落值。研究认为,在600～750万株/hm2的种植密度基础上400 kg/hm2左右的施肥量是高产优质的合理组合。     

An insight into the grain auger injury problem in Queensland, Australia

Grain auger-related injuries were studied by examining the injury data obtained from the Queensland worker's compensation database. Close to 60% of 52 claimants were male employees in the 20 to 34 age group. Fingers, hands, and arms were affected in 65% of all cases, and the auger flighting was involved in 60% of claims. The severity of auger-related injuries is reflected in the high average cost of claims and number of working days lost, which were more than double the all-industries values. Injuries involving the auger flighting are three times more costly (in time and money) than the all-industries values. More claims were made during winter and towards the end of summer, with the majority of injuries occurring in the animal industries. Most incidents occurred in the early or middle periods of a working shift. In addition, two focus group meetings were held to gain a broader perspective of the grain auger injury picture in Queensland, Australia. Focus group participants suggested that the operator's state of mind and attitude to safety are important, while the auger's age, type, and shielding were cited as important risk factors. They suggested that older augers are less likely to be adequately shielded, and mobile augers are most likely to be involved in injury events. The information gained from this study is being used to develop strategies to help farmers minimize injuries associated with the use of grain augers.     

Use of psychrophilic xylanases provides insight into the xylanase functionality in bread making

The bread-improving potential of three psychrophilic xylanases from Pseudoalteromonas haloplanktis TAH3A (XPH), Flavobacterium sp. MSY-2 (rXFH), and unknown bacterial origin (rXyn8) was compared to that of the mesophilic xylanases from Bacillus subtilis (XBS) and Aspergillus aculeatus (XAA). XPH, rXFH, and rXyn8 increased specific bread volumes up to 28%, 18%, and 18%, respectively, while XBS and XAA gave increases of 23% and 12%, respectively. This could be related to their substrate hydrolysis behavior. Xylanases with a high capacity to solubilize water-unextractable arabinoxylan (WU-AX) during mixing, such as XBS and XPH, increased bread volume more than xylanases that mainly solubilized WU-AX during fermentation, such as rXFH, rXyn8, and XAA. Irrespective of their intrinsic bread-improving potential, the dosages needed to increase bread volume to a similar extent were much lower for psychrophilic than for mesophilic xylanases. The xylanase efficiency mainly depended on the enzyme's temperature activity profile and its inhibition sensitivity.     

Proteomic analysis by two-dimensional gel electrophoresis and starch characterization of Triticum turgidum L. var. durum cultivars for pasta making

Criteria for durum wheat quality are continuously evolving in response to market pressure and consumer's preference. Specific attributes of durum wheat for different end products require more rapid and objective means to grade and classify wheat parcels based on processing potential. A total of 10 durum wheat cultivars were compared for compositional, protein, and starch characteristics. Mean values for the gross composition differed for total protein, gluten, and starch. Two-dimensional electrophoresis (2DE) analysis showed the proteome diversity among the cultivars. As shown by the principal component analysis (PCA) applied to 2DE data of gliadin and glutenin fractions, cultivars differed mainly from the number of proteins and levels of protein expression. As determined by the rapid viscoanalyzer (RVA), swelling power, starch damage, amylose content, and starch pasting properties of 10 cultivars differed significantly. 2DE fingerprinting and amylose content seemed to distinguish specific cultivars being useful tools for selecting suitable durum wheat cultivars for pasta making.     

Analysis of protein structures and interactions in complex food by near-infrared spectroscopy. 2. Hydrated gluten

Hydrated gluten, treated with various salts, was analyzed by near-infrared (NIR) spectroscopy to assess the ability of this method to reveal protein structure and interaction changes in perturbed food systems. The spectra were pretreated with second-derivative transformation and extended multiplicative signal correction for improving the band resolution and removing physical and quantitative spectral variations. Principal component analysis of the preprocessed spectra showed spectral effects that depended on salt type and concentration. Although both gluten texture and the NIR spectra were little influenced by treatment with salt solutions of low concentrations (0.1-0.2 M), they were significantly and diversely affected by treatment with 1.0 M salt solutions. Compared to hydration in water, hydration in 1.0 M sulfate salts caused spectral effects similar to a drying-out effect, which could be explained by salting-out.     

氮素形态对强筋和中筋小麦产量和品质的影响

[目的]研究不同氮素形态对强筋和中筋小麦植株生长、籽粒蛋白质含量及产量的影响,为选择适宜氮肥种类、提高氮素利用率提供科学依据.[方法]选用强筋小麦'藁优2018'和中筋小麦'济麦22'在河北邢台进行田间试验.在相同施氮量下,设置5个氮源处理:不施氮肥(CK)、酰胺态氮肥(Urea)、铵态氮肥(NH4+-N)、硝态氮肥(...     

施钾量对强筋小麦产量和品质的影响

以强筋面包小麦“临优145”为试验材料,研究了不同施K量对强筋小麦籽粒产量和品质的影响。结果表明,在施K(K2O)37.5~112.5kg/hm2范围内,随施K量增加,小麦产量逐渐提高,可增产793.5~1672.5kg/hm2,净增收益981.0~1878.0元/hm2,且处理间差异显著,但当施K量增加到150kg/hm2时,小麦产量却降低,中产条件下施用K肥以112.5kg/hm2左右为宜。施K处理对清蛋白影响小,对球蛋白、醇溶蛋白和谷蛋白影响大。施K可显著提高小麦的贮藏蛋白、总蛋白及各种氨基酸含量,进而改善小麦品质。在一定范围内小麦的主要加工品质性状随施K量的增加而改善,与对照相比,湿面筋、沉降值、稳定时间、面包体积和延伸性等重要烘焙品质指标均有改善。本试验条件下,N(N)、P(P2O5)、K(K2O)最佳比例以2∶1∶1、施K量(K2O)103.0~112.5kg/hm2范围内,有利于强筋小麦产量和品质同步提高,实现高产、优质、高效。     

喷灌促进小麦籽粒淀粉积累提高其品质

为研究喷灌和地面灌溉对小麦籽粒淀粉积累及其品质性状的影响,该文以中筋小麦百农矮抗58为试验材料,通过2012-2014年2个生长季的大田试验,以地面灌溉为对照,分析了喷灌对小麦籽粒淀粉及其组分积累过程、淀粉糊化特性等的影响。结果表明:1)与地面灌溉相比,喷灌显著提高了小麦总淀粉和支链淀粉的含量,降低了直链淀粉含量,进而降低了淀粉的直/支比;2)喷灌条件下小麦总淀粉和支链淀粉的积累量较地面灌溉分别显著提高了7.8%~8.0%和12.2%~12.5%(P0.05);3)喷灌条件下小麦直链淀粉的积累量较地面灌溉显著降低了8.3%~11.4%(P0.05);4)Logistics方程模拟淀粉积累过程表明,与地面灌溉相比,喷灌提高了小麦总淀粉和支链淀粉的最大积累速率、平均积累速率,但降低了直链淀粉的最大积累速率、平均积累速率;5)喷灌与地面灌溉条件下淀粉糊化特性表现出明显的不同:除糊化温度和糊化时间差异不显著外,喷灌小麦淀粉的高峰黏度、低谷黏度、稀懈值和最终黏度分别较地面灌溉提高了0.169~0.186、0.053~0.062、0.116~0.124和0.155~0.171 Pa·s(P0.05)。综上,与地面灌溉相比,喷灌有利于中筋小麦成熟期籽粒淀粉积累,并在一定程度上提高了中筋小麦淀粉品质。该研究可为小麦高产优质栽培提供理论依据。     

The role of laboratory, glasshouse and field scale experiments in understanding the interactions between genetically modified crops and soil ecosystems: A review of the ECOGEN project

The interactions of genetically modified (GM) crops with soil species and ecosystems is complex, requiring both specific and broad spectrum assessments. In the ECOGEN project we undertook experiments at three scales of increasing complexity, using Bt maize expressing the Cry1Ab protein from Bacillus thuringiensis as an example. Test species were selected for laboratory-scale experiments to represent taxonomic groups that we could also monitor at glasshouse and field scales (e.g., nematodes, protozoa, micro-arthropods, earthworms, and snails). In the laboratory, single species were exposed to purified Cry1Ab protein or to Bt maize leaf powder incorporated into simplified diets under controlled conditions. In the glasshouse, multiple test species and soil microbial communities taken from ECOGEN's field sites were exposed to Bt maize plants growing under glasshouse or mesocosm conditions. In the field, evaluations were conducted on our selected indicator groups over multiple sites and growing seasons. Field evaluation included assessment of effects due to the local environment, crop type, seasonal variation and conventional crop management practice (tillage and pesticide use), which cannot be assessed in the glasshouse. No direct effects of Cry1Ab protein or Bt leaf residues were detected on our laboratory test organisms, but some significant effects were detected in the glasshouse. Total nematode and protozoan numbers increased in field soil under Bt maize relative to conventional maize, whilst microbial community structure and activity were unaffected. Field results for the abundance of nematodes and protozoa showed some negative effects of Bt maize, thus contradicting the glasshouse results. However, these negative results were specific to particular field sites and sampling times and therefore were transient. Taking the overall variation found in maize ecosystems at different sites into account, any negative effects of Bt maize at field scale were judged to be indirect and no greater than the impacts of crop type, tillage and pesticide use. Although the ECOGEN results were not predictive between the three experimental scales, we propose that they have value when used with feedback loops between the scales. This holistic approach can used to address questions raised by results from any level of experimentation and also for putting GM crop risk:benefit into context with current agricultural practices in regionally differing agro-ecosystems.     

不同追氮时期对两种筋型小麦产量和品质的影响

选用强筋小麦临优145和中筋小麦临优2018,在田间条件下研究追氮时期对其产量和品质的影响。结果表明,在氮肥用量一定时,以拔节期追氮两个品种的产量最高;随着追氮时期的后延,其蛋白质含量、湿面筋含量、干面筋含量、沉降值成上升趋势。不同筋型小麦的粉质参数变化不同,高筋小麦临优145随追氮后延逐渐变优,中筋小麦临优2018冬追较好。     

Molecular definition of black tea taste by means of quantitative studies, taste reconstitution, and omission experiments

Recently, bioresponse-guided fractionation of black tea infusions indicated that neither the high molecular weight thearubigens nor the theaflavins, but a series of 14 flavon-3-ol glycopyranosides besides some catechins, might be important contributors to black tea taste. To further bridge the gap between pure structural chemistry and human taste perception, in the present investigation 51 putative taste compounds have been quantified in a black tea infusion, and their dose-over-threshold (Dot) factors have been calculated on the basis of a dose/threshold relationship. To confirm these quantitative results, an aqueous taste model was prepared by blending aqueous solutions of 15 amino acids, 14 flavonol-glycosides, 8 flavan-3-ols, 5 theaflavins, 5 organic acids, 3 sugars, and caffeine in their "natural" concentrations. Sensory analyses revealed that the taste profile of this artificial cocktail did not differ significantly from the taste profile of the authentic tea infusion. To further narrow the number of key taste compounds, finally, taste omission experiments have been performed, on the basis of which a reduced recombinate was prepared containing the bitter-tasting caffeine, nine velvety astringent flavonol-3-glycosides, and the puckering astringent catechin as well as the astringent and bitter epigallocatechin-3-gallate. The taste profile of this reduced recombinate differed not significantly from that of the complete taste recombinate, thus confirming these 12 compounds as the key taste compounds of the tea infusion. Additional sensory studies demonstrated for the first time that the flavanol-3-glycosides not only impart a velvety astringent taste sensation to the oral cavity but also contribute to the bitter taste of tea infusions by amplifying the bitterness of caffeine.     

施氮量对强筋和中筋小麦产量和品质及养分吸收的影响

以强筋小麦皖麦38和中筋小麦皖麦44为材料,研究了施氮量对子粒产量、品质及植株养分吸收的影响,分析了植株体内N、P、K素含量与子粒品质性状的相关性。结果表明,施氮量在0-300kg／hm2范围内,氮素与两种类型小麦的子粒产量和蛋白质产量均呈二次曲线关系,增施氮素不仅能显著提高蛋白质、湿面筋含量和沉降值,降低弱化度,延长面团的形成时间和稳定时间,有利于植株对氮的吸收,而且还能提高P、K的营养水平。植株体内N的含量除与吸水率和弱化度相关不显著外与其它主要品质性状的相关系数都达到极显著水平,只有容重为负相关;皖麦38和皖麦44达到最高子粒产量的施氮量分别为224.6.kg／hm2和207.5.kg／hm2,达到最高蛋白质产量的施氮量分别为288.5.kg／hm2和221.0.kg／hm2。