Genetic implications of kernel NIR hardness on milling and flour quality in bread wheat

While quantitative measurements of wheat (Triticum aestivum L) kernel hardness are important for market classification of cultivars, their genetic relationship to end-use quality in breeding populations is not well established. After verifying that divergent selection for hardness score (HS) based on near- infrared reflectance (NIR) spectroscopy was effective, the objective was to determine correlated selection responses in milling and flour quality of two hard red winter populations differing widely in parental origin. Selection was applied in the F₃ generation using replicated field plots at two locations. Selection response was evaluated in the F₄ generation at the same locations the following year. Selection for high HS (harder kernels) increased kernel protein concentration in both populations, while low HS selection decreased it. Selection for HS had no consistent and detectable impact on flour yield or physical dough properties (mixograph absorption, mixing time, and mixograph rating or tolerance). Selection for high HS decreased SDS sedimentation volume adjusted for flour protein concentration in both populations, but the magnitude of the response was small (?1.7 ml in actual units; ?0.3 ml after adjustment). Because correlative effects of NIR hardness were primarily expressed in protein quantity and not protein quality, milling and flour quality must be considered independently of NIR hardness if genetic improvement in those traits is desired.     

添加青麦仁粉对小麦粉特性的影响研究

将青麦仁制成全粉添加在小麦粉中,并对它的理化性质、糊化特性及流变学特性进行研究。结果表明:随着青麦仁粉添加量的增大,混合粉的水分、淀粉、湿面筋含量以及面筋指数下降,灰分、蛋白质、膳食纤维、叶绿素、脂肪含量明显升高;粉质特性表现为面团的稳定时间和粉质质量指数下降,吸水率升高,弱化度升高;拉伸特性显示面团的延伸性、能量以及拉伸阻力显著下降;糊化特性呈现出高峰黏度、最终黏度、低谷黏度、回生值以及衰减值整体都呈下降趋势。     

浅谈小麦不完善粒对面粉加工的影响

笔者在实践中认为,小麦不完善粒对面粉加工有着重要影响,如果能把好原粮检验这一关 ,将会对后续的生产过程得到基本有效的保障。1 小麦不完善粒的界定在国家标准GB1351—1999中,对小麦不完善粒有明确的定义。即：受到损伤但尚有食用价 值的颗粒。包括：虫蚀粒、病斑粒（含赤霉病粒和黑胚粒）破损粒、生芽粒和霉变粒。2 各种小麦不完善粒对面粉加工的影响小麦的胚部是籽粒生命活动最旺盛的部位,含有大量的蛋白质、较多的脂肪和活性强的酶 。被害虫蛀蚀后,胚乳比例减少,麦皮的比例增大,势必造成出粉率降低,面粉灰分高,面 筋质量差…     

不同粉路中的小麦粉及其淀粉性质测定

研究了1T下、3M下、1Sf小麦粉及其淀粉的性质,测定了其淀粉、蛋白质、灰分、水分以及直链淀粉的含量,并对淀粉的粒径分布、溶解度和膨润力以及淀粉糊的透明度、冻融稳定性等特性进行了分析。实验结果表明:在小麦胚乳结构中,越接近麦心的部位,淀粉和直链淀粉含量越高,水分和蛋白质含量越低,灰分的差异不大;淀粉颗粒的大小顺序为3M下>1Sf>1T下,粒径呈正态分布;小麦淀粉随温度的升高,溶解度增大,膨润力上升;小麦淀粉糊的透明度较高,冻融稳定性较差。     

Changes in flour lipids during the storage of wheat flour

High- and low-grade spring and winter wheat flours of ～13% moisture were stored at 15, 25 and 37 °C and the lipids were then extracted with water-saturated n-butanol. In the original (control) flours there were more neutral lipids and glycolipids in low-grade winter than in high-grade winter and in low-grade spring than in high-grade spring flours, but there were no corresponding differences in the amounts of phospholipids. The total extractable lipid contents of the flours remained constant in the samples stored at 15 °C, but there were slight losses in the samples stored at 25 and 37 °C. Total lipid contents determined by acid hydrolysis remained constant in all cases indicating that no loss of fatty acids had occurred on storage. There was sufficient hydrolysis of all glycerides to account for the increased amounts of free fatty acids in the stored flours. Some complete deacylation of lipids to free fatty acids and water-soluble products was indicated. The fatty acid composition of all lipids remained constant, and there was no evidence of any lipoxygenase or other enzymic degradation of fatty acids. Stereoanalysis of the principal glycerides indicated that phosphatidylcholine (and probably also phosphatidylethanolamine) was specifically hydrolysed at the 2-position, presumably by phospholipase-A₂. Hydrolysis of triglycerides, diglycerides and monoglycerides was attributed to the action of wheat and microbial lipases of unknown specificity. Stereoanalysis of N-acylphosphatidylethanolamine and the galactosyldiglycerides was not attempted, but it was deduced that they were randomly hydrolysed at the 1- and 2-positions. The changes found in the flour lipids differed from those reported to occur in germinating wheat and in stored damp wheat flour which had been damaged by moulds.     

Microbiology of wheat and flour milling in Australia

A survey was undertaken to determine the microbiological status of Australian wheat and the distribution of microorganisms in the flour milling fractions and end products. A total of 650 milling process and end product samples was obtained from nine flour mills located in New South Wales (4), Queensland (2), Victoria (2) and Western Australia (1) during the 1997-1998 and 1998-1999 wheat seasons. Most frequent (modal) counts in wheat and flour were, respectively, as follows: aerobic mesophilic plate count, 10(5) and 10(2) colony forming units/gram (cfu/g); coliforms, 10 and 1 most probable number/gram (MPN/g); Bacillus spp., 10(4) and 10(2) cfu/g; B. cereus, 1 and 0.1 MPN/g; mesophilic aerobic spores, 10 and 1 cfu/g; aerobic thermophiles, both 10 cfu/g; yeasts, 10(3) and 10(2) cfu/g, and moulds, 10(3) and 10(2) cfu/g. Bacillus spp., coliforms, yeasts and moulds were the most frequently detected microorganisms throughout the survey. The most common moulds isolated were Aspergillus, Penicillium, Cladosporium and Eurotium spp. Environmental serovars of Salmonella were isolated from two samples. Escherichia coli and B. cereus were present at very low levels, a majority of positive samples being at the minimum level of detection (3 and 0.3 MPN/g, respectively). As wheat grain layers are separated, surface-adhering contaminants are concentrated in end product bran, wheat germ and pollard, which comprise the outer layers of the grain. Consequently, the inner endosperm fraction contains lower microbial counts, and flour is the cleanest end product of the milling process. Higher microbiological counts midstream in the milling process indicate that equipment contamination may contribute to microbiological contamination; however, the microbiological quality of incoming wheat has a strong influence on the ultimate quality of milling end products.     

Distribution of deoxynivalenol and nivalenol in milling fractions from fusarium-infected Japanese wheat cultivars

The fate of the Fusarium mycotoxins deoxynivalenol and nivalenol during the milling of Japanese wheat cultivars artificially infected with Fusarium was investigated. Grain samples with different mycotoxin concentrations were milled using a laboratory-scale test mill to produce eight fractions: three breaking flours (1B, 2B, and 3B), three reduction flours (1M, 2M, and 3M), wheat bran, and wheat shorts. Patent flour for human consumption was made from the 1B, 2B, 1M, and 2M flours, and low-grade flour was made from 3B and 3M flours. The four resulting samples (patent flour, low-grade flour, bran, and shorts) were analyzed for deoxynivalenol and/or nivalenol with an in-house validated analytical method using high-performance liquid chromatography with UV absorbance detection. In samples with different mycotoxin concentrations, the distribution of those toxins differed among the milling fractions. Grains with a lower level of contamination produced bran and shorts samples with a high relative concentration of nivalenol. A high percentage of nivalenol was found in patent flour, followed by bran. Contrary to the less-contaminated sample, the concentration of nivalenol in moderately contaminated grain was high only in the shorts sample. The highest percentage of deoxynivalenol and nivalenol was observed in the patent flour. The results of this study indicate that the distribution of deoxynivalenol and nivalenol in milled Japanese wheat could be influenced by the contamination level of the original grain, and the milling process is not always effective for removal of toxins from wheat grains.     

Distribution of T-2 and HT-2 toxins in milling fractions of durum wheat

The effect of processing on mycotoxin content in milling fractions has been investigated in 10 samples of durum wheat contaminated with T-2 and HT-2 toxins at levels ranging from 97 to 5,954 μg/kg (sum of T-2 and HT-2 toxins). Either naturally contaminated samples or samples artificially inoculated with Fusarium sporotrichioides under field conditions were used. A method based on liquid chromatography-tandem mass spectrometry coupled with immunoaffinity column cleanup was validated in-house for the simultaneous analysis of both toxins in a variety of matrices, including uncleaned wheat, cleaned wheat, screenings, bran, red dog, fine middlings, and semolina. Mean recoveries from samples spiked with T-2 and HT-2 toxins at levels of 100 μg/kg ranged from 85 to 107%, with relative standard deviations (RSDs) lower than 14%. The milling process led to an increase of T-2 and HT-2 toxin contents up to 13- and 5-fold in screenings and bran, respectively, compared with occurrence in the uncleaned wheat; however, an overall reduction of T-2 and HT-2 toxins by 54% (RSD, 20%) and 89% (RSD, 3%) was observed in cleaned wheat and in semolina, respectively.     

软质小麦专用粉加工品质控制

介绍了软质小麦及软质小麦专用粉加工特点、操作要点,以及软质小麦粉的主要控制指标和内在品质。     

小麦制粉清理工段的新工艺

论述了制粉工业的发展趋势,介绍了制粉工业近年来清理工段的新工艺,采用最新清理工艺,满足了洁净化生产的要求,降低了成品微生物指标.     

Distribution of toxigenic Fusarium spp. and mycotoxin production in milling fractions of durum wheat

A reliable and sensitive PCR assay to specifically detect trichothecene-producing Fusarium spp. in milling fractions and kernel tissue of naturally infected durum wheat is reported. Assays were based on a combination of primers derived from the trichodiene synthase and the β-tubulin genes. The occurrence of toxigenic Fusarium spp. in semolina and wheat tissue (grain ends, crease, pericarp, aleurone layer, germ and albumen) was detected, even for a weakly contaminated wheat sample. Penetration of toxigenic Fusarium spp. into the interior of durum wheat kernel was demonstrated for the Nefer variety, indicating that none of the tissue structures within the wheat kernel acted as an effective barrier to fungal invasion. Moreover, after inoculation by toxigenic Fusarium strains, semolina was shown to allow high yields of trichothecenes, while bran was demonstrated to contain biochemical inhibitors able to significantly reduce trichothecene production. These results will be useful in improving breeding strategies to control trichothecene contamination of durum wheat kernels.     

Thermal and dynamic rheological properties of wheat flour fractions

A commercial high gluten flour (HGF) was fractionated into prime starch (PS), tailing starch (TS), and gluten (G). Fractions were examined alone or in various combinations. Dynamic rheological properties of samples were measured in an oscillatory rheometer (strain 0.02; frequency 0.1 Hz) during heating at 1°C/min. Thermal characteristics of samples were determined by differential scanning calorimetry (DSC) at a heating rate of 10°C/min. The loss (G″) and storage (G′) moduli of PS and mixed G/PS, G/TS, and G/PS/TS increased after 60°C, reaching peak values (e.g. 81, 301, 313, and 3000 Pa in G′, respectively) around 75°C after which the moduli decreased. HGF showed a steady increase in G′ from 32 to 2490 Pa as temperature increased from 65 to 90°C, indicating continuous formation of elastic networks. Cooling increased G′ for G/PS/TS, decreased G′ for HGF, and produced no rheological transitions for all samples. TS and G alone did not exhibit appreciable viscoelastic responses to the heating and cooling temperatures. DSC measurements revealed a major endothermic transition in HGF. This transition, with a peak around 60°C, was due to starch gelatinization. The presence of G or TS resulted in reduced melting enthalpies of starch in the PS fraction. Gluten or TS fractions alone or in combination did not exhibit any endothermic transitions.     

糯小麦实验制粉及其在面条中的应用研究

报告了糯小麦的实验制粉,测定了糯小麦粉的理化特性,并对糯小麦粉在面条中的应用进行了研究,结果表明:与普通小麦相比,糯小麦的体积质量大;与普通小麦粉相比,糯小麦粉湿面筋含量高但面筋指数低,吸水率较高,延展性较差,降落数值极低;糯小麦粉能显著增强面条的适口性、光滑性和粘性,其最佳添加比例在30%左右。     

Impact of endogenous constituents from different flour milling streams on dough rheology and semi-sweet biscuit making potential by partial substitution of a commercial soft wheat flour

A flour fractionation-reconstitution procedure was used to study the substitution of a commercial soft wheat flour with gluten, water extractables, prime starch and starch tailing fractions isolated from patent and clear flour streams on dough rheology and semi-sweet biscuit characteristics. Substitution of soft wheat flour with increasing levels of the native patent and clear flour streams raised the dough consistency, hardness and elastic properties as well as the biscuit textural attributes (density, hardness). The dough stickiness of the base flour was also reduced and the biscuits were free of cracks. Gluten isolated from the patent flour had a greater impact on dough consistency, hardness and elastic properties than gluten obtained from the clear flour, likely due to the superior protein quality of the former. Additionally, with increasing gluten levels in the fortified flour there were moderate increases in biscuit density, hardness, and lower crunchiness. The addition of starch tailings produced the largest impact on consistency and hardness of the dough. This fraction also exerted a pronounced effect on biscuit density and hardness, while it lowered crunchiness, presumably due to its higher pentosan content. Overall, the dough rheological properties and biscuit characteristics were controlled by the amount-nature of the fractions added; i.e., besides gluten (amount and quality), other constituents such as pentosans and the overall composition of the flour blends can largely affect the quality of the semi-sweet biscuits.     

研磨方式对小麦粉粉体特性的影响

以扬麦20、新麦26籽粒为原料制备胚乳颗粒粉,再用撞击磨、锤式磨、高速粉碎机进行不同程度的粉碎得到不同粒度的小麦粉,测定水分、灰分等基本理化指标,经激光粒度仪和粉体综合特性测试仪测定粉体的流动性相关指标,并用Carr指数法对小麦粉流动性进行综合评价分析。结果表明:3种研磨方式中,经撞击磨研磨所得小麦粉流动性最好,而经锤式磨及粉碎机研磨所得小麦粉的流动性之间无显著性差异(P≥0.05),但锤式磨所得小麦粉水分较低。     

脱皮制粉清理工艺的改进

简要介绍了脱皮制粉工艺中，清理脱皮工艺的改进和调整，主要设备选用和布置，分析了工艺效果，介绍了工艺操作技术。     

Effect of different milling methods on chemical composition of whole wheat flour

In order to assess the effect of different types of milling methods on protein and lipid composition of whole wheat flour, two types of wheat varieties belonging to strong and weak wheat type were selected and milled in different mills such as plate, hammer, stone and roller mills. The temperatures generated during grinding of wheat in stone, plate, hammer and roller mills were 90, 85, 55 and 35 °C respectively. The studies on SDS-PAGE indicated degradation in proteins of whole wheat flour obtained from stone and plate mills, especially in the high molecular glutenin regions. Greater loss of total amino acids was also observed in the above milled flours when compared with that of hammer and roller milled samples. Free lipid content was lower in flours milled in stone and plate mills when compared with that of flours milled in other mills. Unsaturated fatty acid content, particularly linolenic acid, was lower in stone milled flour (1.3%) followed by plate mill (2.2%), hammer mill (2.8%) and roller flour mill (3.8%). The trends in the above values as influenced by different milling methods remained similar both in the weak and strong wheat types.     

发芽时间对不同系统小麦粉品质的影响

将豫农035小麦按不同时间梯度发芽后,进行常规水分调节并研磨制粉,探讨小麦发芽程度对不同系统小麦粉品质的影响。实验结果表明,虽然发芽6h后各系统小麦粉的降落数值均明显下降,并随发芽时间的增加而逐渐下降,不同系统小麦粉品质指标的变化有相近的规律,却也不尽相同。随着发芽时间的增加,不同系统小麦粉的出粉率、湿面筋含量、面筋指数、峰值黏度、回生值、衰减值、最终黏度均呈现不同程度的下降,而当发芽时间为24~48h时,降幅显著;不同系统小麦粉的水溶物、灰分、损伤淀粉含量有所增加,但不同系统及发芽时间段的变幅不同,其中1M、2M粉的水溶物增幅较大;而发芽48h后,各系统小麦粉损伤淀粉含量均显著增加。     

面粉中添加过氧化苯甲酰的安全性

对过氧化苯甲酰给面粉品质带来的影响及其使用中的安全性进行了探讨,并对我国使用过氧化苯甲酰的现状进行了分析.     

Use of durum residue flour,a lower value product of durum milling,by incorporation into wheat flour dough without deterioration in baking quality

BACKGROUND: During the milling of durum wheat to semolina, about 10–15% of total products produced is residue flour, a lower value product than the semolina. This study investigated the potential for using the durum residue flour as an additive in bread‐making to improve its potential commercial value. RESULTS: Incorporation of residue durum flour from 102 breeding lines into a low protein flour and standard bakers' flour at 20% incorporation improved the bake loaf volume with minimal change in Mixograph dough mixing time and peak resistance in many of the lines tested. Loaf yellow b was always increased even with only a 10% incorporation. Baking flours can tolerate 20% incorporation with no deleterious affects on loaf volume and bake score. CONCLUSION: The results show a potential for using the lower value durum residue flour for baking bread of acceptable quality with a slightly higher yellow colour. This would improve the profitability for the miller and provide alternative ingredients to the baker for preparing specialty breads. Copyright © 2008 Crown in the Right of the State of New South Wales and Society of Chemical Industry