On Predicting Roller Milling Performance V: Effect of Moisture Content on the Particle Size Distribution from First Break Milling of Wheat

Extended breakage functions incorporating both single kernel size and moisture content were determined for First Break milling of hard and soft wheats under a sharp-to-sharp disposition. A moisture correction function was constructed by milling narrow size fractions of wheat tempered to different moisture contents, and subtracting the breakage function at a base moisture content of 16% from that at other moisture contents. The effect of adding moisture was to change an initially inverted U-shaped distribution at low moisture contents to a linear distribution at 16% moisture, then to a U-shaped distribution at higher moisture contents, reminiscent of the particle size distributions produced by dull-to-dull milling. The extended breakage functions were used to predict milling of unseparated feed samples at different roll gaps and moisture contents. In addition, mixtures of hard wheat at 14% moisture and soft wheat at 20% moisture, mixed in different proportions, were milled and the resulting particle size distributions compared with predictions. Excellent predictions were obtained in all cases. This confirms the independent breakage of kernels during First Break milling, and demonstrates the potential of the breakage function approach for interpreting single kernel data in terms of predictions of milling performance.     

陕西关中小麦品种籽粒硬度及测定方法研究

采用四种测定小麦硬度的方法对陕西关中地区33个小麦品种（品系）的籽粒硬度进行了评价，结果表明，陕西关中小麦有9．1属于硬麦，78．8％属于中硬麦，12．1％属于软麦。提出颗粒指数法（PSI），研磨体积法，近红外法（NIR），角质率法测定小麦硬度的评价标准。结果认为：PSI法，研磨体积法和NIR法测定结果的分布对应性较高，NIR法与其它测定方法相关性较高，高角率法有一定局限性。     

Endosperm Texture in Wheat

One of the fundamental means of classifying wheat is through its endosperm texture. It impacts significantly on the milling process affecting among other things flour particle size and milling yield. Hardness in wheat is largely controlled by genetic factors but it can be affected by the environment and factors such as moisture, lipid, and pentosan content. The principal genetic locus controlling endosperm texture in wheat, Ha, is located on the chromosome 5D. At this locus several genes, notably the puroindolines, have been identified. Puroindolines are the major components of the 15 kDa protein band associated with starch granules that is more abundant in soft wheats than in hard. Recently the puroindolines have been shown to enhance grain hardness in rice. In this review we discuss the structure of hard and soft wheat endosperm with particular emphasis on when differences in endosperm texture can be detected in the developing seed. The role of the environment and other factors that may affect the endosperm texture is also examined together with the role of the puroindoline genes at theHa locus. Finally, we compare endosperm hardness in wheat and in barley.     

Analysis of the milling reduction of bread wheat farina: Physical and biochemical characterisation

The reduction of coarse farina during milling from five representative hard and soft French bread wheat cultivars was followed step by step. Particle size distribution of the milled products and energy required to dissociate wheat farina revealed large differences between cultivars. A grinding index (required energy to produce 1 kg of flour), K′, corresponding to the energy necessary to obtain a given amount of flour, was found to be related with both grain hardness and vitreousness. Analysis of particle size distribution suggested a major influence of hardness in the production of fine particles <50 μm during the reduction process. On the other hand, vitreousness appeared to impact on the extent of coarse particle size reduction. Differences in farina reduction behaviour of the wheats analysed were related to their endosperm mechanical properties as determined by compression tests and structural characteristics as measured by Hg intrusion porosity. Vitreousness appeared to affect the endosperm extensibility and degree of porosity. The profile of the different lipid and protein classes in the reduction products of two cultivars showing opposite behaviour as well as different PINA/PINB ratio were determined. The results suggest that the most resistant parts of the grain are enriched in glycolipids, whereas phospholipids appear associated with the most friable parts, at least in the soft wheat grains tested.     

Comparison of Polyphenol Oxidase Activities in Wheats and Flours from Australian and U.S. Cultivars

Polyphenol oxidase (PPO) activities of wheats from various classes and cultivars (grown both in the U.S.A. and in Australia), of some U.S. and Australian wheats, of wheat flours at various extraction rates and of kernels separated by size from various cultivars were measured by the oxygen electrode method. PPO activity of wheats was affected by both cultivar and growing location. Wheat flour contained on the average 3% of the PPO of the wheat grain. PPO activities of the flours increased as the flour extraction rates increased. Contrary to expectation, for a single cultivar, small kernels contained less PPO (on a weight basis and especially on a kernel basis) than did large kernels. Differences among kernels of various sizes for a single cultivar were smaller than differences in PPO among kernels of comparable sizes among various cultivars.     

Field emission scanning electron and atomic force microscopy,and Raman and X-ray photoelectron spectroscopy characterization of near-isogenic soft and hard wheat kernels and corresponding flours

Secondary field emission scanning electron microscopy (FE SEM), atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate native near-isogenic soft and hard wheat kernels and their roller milled flours. FE SEM images of flat-polished interior endosperm indicated distinct differences between soft and hard wheats with less internal continuity in the soft wheat, whereas individual starch granules were much less evident in the hard kernel due to a more continuous matrix. AFM images revealed two different microstructures. The interior of the hard kernel had a granular texture with distinct individual spheroid features of 10–50 nm while the images obtained for the soft kernel revealed less distinct small grains and more larger features, possibly micro-structural features of starch granules. Raman spectra resolved identical distinct frequencies for both kernel types with slightly different intensities between types. Finally, the chemical surface compositions of flour for these two types of kernels obtained by XPS provided subtle insight into the differences between soft and hard wheat kernels. These combined advanced microscopic and spectroscopic analyses provide additional insight into the differences between the soft and hard wheat kernels.     

Genetic and environmental factors affecting grain texture in common wheat

Thirteen wheat cultivars grown in six locations were compared for kernel weight, protein content and grain texture, as determined by the Single Kernel Characterization System (SKCS). Moreover, puroindolines a (Pin-A) and b (Pin-B) bound to starch were quantified by densitometric scanning of A-PAGE fractionations. All cultivars shared allele Pina-D1a coding for wild-type Pin-A, and differed from each other in allele composition at Pinb-D1 coding for Pin-B. Cultivars with Pinb-D1a exhibited soft grain and high amounts of Pin-A and Pin-B compared to cultivars with Pinb-D1b or Pinb-D1d. Significant genetic variation for grain hardness and Pin-A level was detected in soft cultivars. The ratio between Pin-A and Pin-B levels in soft cultivars was approximately 6:5, whereas it varied between 9:5 and 10:1 in hard cultivars. Protein content was significantly correlated with Pin-B content (r=0.34) and SKCS value (r=0.36) in soft wheats. Significant correlations (0.68 and 0.73 for soft and hard wheats, respectively) were observed between Pin-A and Pin-B levels. Grain hardness was not correlated with puroindoline levels and Pin-A/Pin-B ratio in both textural classes. By contrast, kernel weight was found to act as a major environmental factor affecting grain texture in both soft and hard wheats.     

Low molecular phytochemicals of Indian dwarf (Triticum sphaerococcum Percival) and Persian wheat (T. carthlicum Nevski) grain

Ancient wheat grain is considered by consumers to be more natural, pro-healthy and better tolerated, so these genotypes are being steadily reintroduced to cultivation. This study presents the content and composition of phenolic acids, alkylresorcinols, sterols, tocols and carotenoids in the grain of Indian dwarf and Persian wheats, extended by characteristics of their kernels (weight, dimensions and colour). To compare these features, four other wheat species (bread, spelt, durum and einkorn wheats) were used. It was found that the grain of Indian dwarf and Persian wheat is similar in weight and dimensions to grain of einkorn wheat, while in colour to bread wheat. Among the tested samples, grain of both new genotypes was the richest source of total low molecular phytochemicals, especially phenolic acids and alkylresorcinols, while being the weakest source of carotenoids. For these wheats, an enhanced share of ferulic acid (93–95%) was found, accompanied by higher quantitative and qualitative variability of homologues within sterols, tocols and carotenoids. In turn, the alkylresorcinol composition was related to wheat ploidy level.     

Investigation of the effect of conditioning on the fracture of hard and soft wheat grain by the single-kernel characterization system: A comparison with roller milling

A study has been carried out on selected hard and soft Australian wheats to determine the effect of conditioning on the crush-response profiles (CRPs) measured using the single-kernel characterization system (SKCS 4100). In addition, the fragmentation patterns that resulted from crushing in the SKCS have been compared with those that resulted from the first break stage of roller milling. It was found that the CRPs were changed significantly (P<0.05) as a result of conditioning. In particular, the rheological parameters shell stiffness and strength and endosperm strength all decreased following conditioning. The fragmentation patterns, assessed using low-resolution microscopy and particle size analysis, that resulted from the crushing of unconditioned wheat in the SKCS were the closest match with those that resulted from first break milling of conditioned wheat. These results show how the SKCS may be used to monitor the progress of wheat conditioning prior to milling. They also provide support for the use of SKCS measurements on unconditioned wheat for the prediction of milling performance.     

陕西小麦籽粒硬度及其基因型分析

籽粒硬度与小麦市场分级定价、磨粉品质和食品加工品质密切相关。为给小麦品种选育和品种推广提供参考依据,用单籽粒谷物硬度测试仪测定了169份陕西小麦品种（系）的籽粒硬度,并利用分子标记检测和基因序列分析确定了硬质麦的基因组成。硬度测定结果表明,陕西参试小麦品种（系）存在硬质麦、混合麦和软质麦3种类型,分别为121、11和37份,依次占71.6%、6.5%和21.9%。陕西不同地区3种籽粒硬度类型所占比例明显不同。基因型分析结果表明,陕西硬质麦存在4种基因型,即PinaD1b、PinbD1b、PinbD1d和PinbD1p,分别有14、97、2和8份材料,占硬质麦比例依次为11.6%、80.2%、1.6%和6.6%。总体而言,陕西小麦以硬质麦为主,硬质麦主要由PinbD1b基因型组成。     

Structure,chemical composition and enzymatic activities of pearlings and bran obtained from pearled wheat (Triticum aestivum L.) by roller milling

While abrasive pearling (also referred to as debranning) of wheat kernels prior to milling increases the quality of the resultant flour for producing bread, the potential applications of the co-products of pearling is largely unknown. We studied the impact of different degrees of pearling (0, 3, 6, 9 and 12% by weight) on the composition of pearlings and bran obtained when subsequently roller milling pearled wheat kernels. Pearling does not remove the kernel outer tissues homogeneously as abrasion affects especially the accessible parts of the kernels. Nevertheless, the first 3% removed consisted of mainly pericarp. With 6% or more removed, a significant amount of starchy endosperm ended up in the pearlings. The starting bran material and bran obtained by subsequent roller milling of pearled wheat kernels had similar compositions but the latter had a lower average particle size. Moreover, removal of the outermost kernel layers substantially decreased the enzyme activity levels in the bran.     

江苏淮北地区小麦品种资源籽粒硬度基因等位变异的KASP检测

为了解江苏淮北地区小麦品种资源的籽粒硬度概况及硬度基因型分布规律,以74份近年来江苏淮北地区所育品种(系)和38份来自黄淮其他麦区的常用亲本为材料,采用单籽粒谷物硬度测试仪、KASP标记检测技术和基因扩增及测序技术对其SKCS硬度值及硬度基因型进行鉴定。硬度检测结果表明,供试小麦品种(系)硬度变化范围较大,但硬质麦的比例最大,为70.5%。与常用亲本相比,江苏淮北地区育成品种中软质麦比例较高,为34.3%,但在高代品系中软质麦比例下降到20.5%。基因型检测结果表明,在Puroindoline-D1位点,供试品种(系)中共检测到4种基因型,即野生型(Pina-D1a/Pinb-D1a)、Pina-D1b、Pinb-D1b和Pinb-D1p,其频率依次为25.0%、2.7%、67.9%和4.5%。其中,野生型和Pinb-D1p主要分布在江苏淮北地区。不同硬度基因型的硬度值也存在差异,其中以Pina-D1b基因型的硬度值最高,野生型(Pina-D1a/Pinb-D1a)硬度值最低,Pinb-D1b和Pinb-D1p两硬质类型的籽粒硬度没有显著性差异。在Pinb-2位点,供试品种(系)中共检测到25份材料为Pinb-B2b基因型,包含21份硬质麦、2份混合麦和2份软质麦,其平均硬度值为63.8。     

不同硬度小麦品质差异的分析

为了解不同硬度级别小麦的品质差异,并为新国标<小麦硬度测定硬度指数法>在中国小麦硬度测定中的推广和应用提供参考依据.选取硬质小麦、中硬小麦和软质小麦各6个品种,分别对其品质性状进行测试.结果表明,小麦耔粒硬度与沉淀值、湿面筋含量、破损淀粉含量、面包评分等小麦品质特性和加工特性达极显著相关关系.容重、出粉率和破损淀粉含量随着硬度指数值的升高逐渐增加,但其差异仅在软质小麦与硬质小麦之间达显著水平.硬质小麦与中硬小麦之间未达显著水平.随着硬度指数的升高,面粉蛋白质含量逐渐升高,粗淀粉含量逐渐降低,且在不同硬度小麦级别之间都迭显著水平;直链淀粉占样品的比重逐渐降低,支链淀粉含量升高;面包、面条的加工品质逐步得到了改善,其中面包品质的改善较面条品质更为显著.     

黄淮冬麦区区试小麦品种（系）的品质性状分析及评价

采用国际标准分析方法，对1998－1999年度黄淮冬麦区区试18个参试小麦品种（系）的籽粒品质、蛋白质品质、磨粉品质、粉质参数等品质性状进行了系统的测定和分析。结果表明，参试品种的籽粒硬度、蛋白质含量、湿面筋含量总体水平较高，沉淀值多数属于中、中低类型、稳定时间多数属于中、低类型、大多数参试品种的软化度过高，评价值偏低。     

Simple ELISA Detection of a New Polymorphic Ha Locus Encoded Protein

A rapid two-site sandwich ELISA was developed for detection of a previously uncharacterised protein encoded at the Ha locus on chromosome 5DS of wheat (Triticum aestivum). The assay used the combined specificity of two antibodies to detect a protein that was soluble in aqueous alcohol, salt solutions and water. It was expressed in the endosperm of all soft wheats and Triticum tauschii accessions tested. The ELISA was highly specific, with no signal obtained with varieties that did not express the protein. The presence of the 5DS-encoded protein correlated with a significant change in both water absorption and average hardness and particle size indices in a doubled haploid population derived from a cross between cvs. Cranbrook×Halberd. Only some hard varieties expressed this protein indicating that the protein is not predictive for hardness. However, it may be a new factor, or a marker for a new factor, affecting kernel texture. A polypeptide ofM_r 66 000 was purified from an extract of Halberd flour by immunoaffinity chromatography. Its N-terminal amino acid sequence identified it as an albumin with high homology to both mammalian serum albumins and sucrose synthase from a range of cereals. The assay may be valuable in wheat breeding programmes for assessing kernel texture where the parents are of different ELISA phenotype, or for varietal identification, as the expression of the polypeptide is variable in hard wheat varieties.     

利用研磨法测试玉米子粒耐破碎性的初步研究

利用PX-MFC90D数字式超细研磨仪测定玉米子粒破碎率,评价玉米子粒耐破碎性,探寻快速准确的测定方法及其影响因素,并以此表征不同品种耐破碎性。结果表明,测试子粒样本质量、转速、碾磨时间均对子粒破碎率有显著影响。随子粒样本质量的增加,破碎率呈下降趋势,两者符合二次曲线关系;随着转速和碾磨时间的增加,破碎率呈线性增加。可以用子粒破碎率达50%和100%需要的碾磨时间、转速作为评价玉米品种耐破碎性的指标。研究认为,PX-MFC90D数字式超细研磨仪可用于测定和表征玉米品种的耐破碎性。     

小麦单籽粒性状与品质的关系

目前测定小麦单籽粒品质的方法有单籽粒谷物品质测定法和谷蛋白溶涨指数法(SIG)。为了揭示单籽粒品质检测的作用,选用16个小麦品种(系)进行单籽粒性状的研究,结果表明,品种内单籽粒硬度、籽粒直径、单籽粒重量及SIG的变异较大,水分含量变异不大。单籽粒品质指标硬度、粒重、粒径及SIG与磨粉品质、面团流变学特性、蛋白质品质、籽粒品质部分指标呈显著或极显著相关,这些指标对于预测磨粉品质、早代株系品质筛选及食品品质具有快速、方法简单及预测能力强的优点。将单籽粒谷物品质测定参数及SIG相结合,可以有效地进行小麦育种后代筛选及品质预测。     

小麦粉溶剂保持力与籽粒硬度及蛋白质含量的关系

为了探讨小麦粉溶剂保持力(SRC)与籽粒硬度及蛋白质含量之间的相关性,选用19份小麦品种为试验材料,分别对不同生态地点下的小麦粉SRC、籽粒硬度和蛋白质含量进行了测定.结果表明,籽粒硬度与小麦粉水SRC、碳酸钠SRC和乳酸SRC间相关达1%显著水平,相关系数分别为0.8518、0.7453和0.8523,与蔗糖SRC间相关不显著;蛋白质含量与蔗糖SRC、乳酸SRC间相关达5%显著水平,相关系数为0.5545和0.5206,与水SRC及碳酸钠SRC间相关不显著.多元逐步回归分析表明,在小麦粉4种SRC中,籽粒硬度能够解释乳酸SRC变异的72.6%,蛋白质含量能够解释蔗糖SRC变异的30.7%,回归方程分别为Y(Hardness)=1.814X(LASRC)-120.242和Y(Protein content)=0.081X(SSRC)+3.363.参试材料在不同地点的品质指标与所有地点品质指标平均值间极显著正相关,其中合肥点与品质指标平均值之间总体相关程度较高;不同地点间小麦粉4种SRC极显著正相关,差异表现存在一致性.     

Mapping kernel texture in a soft durum (Triticum turgidum subsp. durum) wheat population

Kernel texture (”hardness”) is one of the major determinants of wheat quality and is primarily controlled by the Puroindoline (Pin) genes, located at the Hardness (Ha) locus. The absence of the Ha locus is responsible for the extremely hard kernels of durum wheat (T. turgidum subsp. durum). Recently, the Pin genes from a soft common wheat variety were introgressed into durum wheat through homoeologous recombination. The objective of this study was to map kernel hardness in a soft durum wheat population derived from the cross between the varieties “Creso” and “Langdon 1–678“. In all, 428 F₆ lines were evaluated for kernel hardness through the Single Kernel Characterization System; Hardness Index (HI) values ranged from −2 to 44. The same lines were genotyped using genotyping-by-sequencing, targeted amplicon sequencing, and sequence-tagged-site markers. A total of 8537 markers were used to conduct single marker-trait association analysis and two major significant regions were identified on chromosomes 3AL and 6AS each responsible for an additive effect of ∼6 HI units. Kompetitive allele specific markers targeting these regions were selected and tested in the whole population. To date, this is the first study to investigate the genetic factors behind hardness variation in durum wheat.     

Milling efficiency of triticale grain for commercial flour production

Triticale is a high yielding cereal grain, however low milling yields have discouraged its utilisation as a wheat alternative in processed flour products. This research investigated the role of hardness, grain size and tempering moisture on milling yields in modern triticale genotypes which do not exhibit shrivelled grain morphology. Replicate samples of three triticale varieties grown in two environments with a bread wheat standard were milled at five moisture contents. Both milling yield and ash content increased with decreasing tempering moisture in all genotypes. Triticale milling yield was between 7.1% and 10.1% less than wheat when tempered between 11% and 15% moisture respectively. The very hard textured triticale exhibited extremely low milling yield, similar to durum wheat. The ratio of ash in flour compared to bran was greater in triticale and the ash content of triticale flour could not be reduced to the level of wheat by alteration of tempering moisture. Surface area of larger triticale grain may also influence ideal tempering moisture, however further investigation is required. Milling yields and flour protein content in triticale can be improved by tempering triticale to lower moisture content, provided high ash content is not considered unfavourable in the final product.