A new lean no time test baking method with improved discriminating power

In response to customer concerns related to gluten strength in commercial baking, the Canadian Grain Commission assessed whether the Canadian Short Process (CSP) test bake method was generating useful data related to intrinsic strength of wheat varieties. Assessment of CSP loaf volume data for Canadian variety trials spanning 2003 to 2013 showed very little correlation with dough strength parameters as measured by farinograph and extensigraph. A lean no time (LNT) test baking method was developed that can better discriminate genotypes and provide objective indicators of the effect of intrinsic dough strength on baking quality. From early method development, through method validation and verification using diverse sets of samples targeting different Canadian wheat classes and grown in three different crop years, results showed the LNT method to be more discriminating and easily adopted by other laboratories. In 2015, the LNT method was adopted as the method of choice in future Canadian variety registration trials. The LNT method is fast, simple and well-suited to high throughput test baking conditions encountered in the evaluation of large numbers of breeder lines. A new objective parameter, loaf top ratio, was also introduced and found to correlate well with dough strength and dough handling properties.     

小麦鲜面片色泽的影响因素研究

为了探讨小麦多酚氧化酶(PPO)活性对鲜面片色泽的影响程度,测定了52个小麦样品的鲜面片色泽、面粉色泽、蛋白质含量、硬度、黄色素含量以及PPO活性的差异.相关分析结果表明,鲜面片色泽主要与蛋白质含量、黄色素含量以及PPO活性有关.蛋白质含量是影响面片色泽L*值的重要因素,与面片放置0 h和24 h的亮度L*值呈极显著负相关,相关系数分别为-0.85和-0.64;黄色素含量与面片放置0 h和24 h的黄蓝度b*值呈极显著正相关,r分别为0.88和0.71,与放置0 h、24 h的红绿度a*值极显著负相关,r分别为-0.58和-0.44,而与L*值相关不显著;PPO活性与0 h鲜面片的L*值没有明显相关,但与24 h面片的L*值呈极显著负相关(相关系数为-0.44～-0.47),与面片放置24 h后L*值的下降值呈极显著正相关(相关系数为-0.45～-0.55).因此,鲜面片的初始亮度L*值与PPO活性无关,主要取决于蛋白质含量,放置24 h后的面片L*值既取决于蛋白质含量,也取决于PPO活性.     

Modification of protein structure and dough rheological properties of wheat flour through superheated steam treatment

Native (NF, 13.5% w.b) and moistened (MF, 27% w.b) wheat flours were treated with superheated steam (SS) at 170 °C for 1, 2 and 4 min, and their protein structure as well as dough rheological properties were analyzed. Confocal laser scanning microscopy (CLSM) and SDS-PAGE patterns indicated the formation of protein aggregates with reduced SDS extractability after treatment. Farinograph and dynamic rheometry measurements showed that the strength as well as elastic and viscous moduli of the dough made from SS-treated flours progressively increased with SS treatment time. And both the improvements were more pronounced for superheated steam-treated moistened flours (SS-MF) than for superheated steam-treated native flours (SS-NF). Size-exclusion high performance liquid chromatography (SE-HPLC) analysis demonstrated that dough rheological parameters have positive correlations with SDS unextractable polymeric proteins (UPP) contents. SS treatment on flours led to a transition of protein secondary structures to more ordered form (α-helix and β-sheet). Additionally, free sulfhydryl (SH) contents decreased after treatment, which implied that disulfide bonds accounted for protein extractability loss and dough rheological properties improvement. Elevated moisture level promoted the modification of both protein structure and dough behaviors of flours during SS treatment.     

Changes in the physical and the sensorial properties of wheat bread caused by interruption and slowing of the fermentation of yeast-based leaven

Here we propose an original study on the effect of an interruption and slowing of the fermentation of yeast-based leaven on the physical properties of bread.     

A simple approach to predicting dough sheeting thickness

The prediction of final sheet thickness after rolling of wheat flour dough is studied using an approximate method that concentrates on the initial, intermediate and final material configurations. A newly proposed viscoelastic constitutive model containing a damage function is used. Compressibility and sideways spreading are ignored. Predictions of final sheet thickness given roll speed and diameter, gap and initial thickness data, show excellent agreement with available experiments on unyeasted dough, in contrast to many previous attempts.     

Changes in bread-making quality attributes of bread wheat varieties cultivated in Spain during the 20th century

Genetic gains in quality traits were assessed in grain samples from 4 field experiments involving 16 bread wheat varieties representative of those most widely cultivated in Spain during the 20th century. The allelic composition at three glutenin loci (Glu-A1, Glu-B1, and Glu-D1) was obtained by PCR-based DNA markers and published references. From 1930 to 2000 grain protein content decreased by −0.030% y⁻¹, or in relative terms by −0.21% y⁻¹, but the protein produced per hectare increased by 0.39% y⁻¹. Alveographic tests revealed significant changes in dough rheological properties. Dough strength (W) and tenacity (P) increased at relative rates of 1.38% y⁻¹ and 0.99% y⁻¹, respectively, while dough extensibility (L) decreased by −0.46% y⁻¹, resulting in an increase of 1.45% y⁻¹in dough equilibrium (P/L). The rise in protein quality could be related to the replacement of the null allele by subunits 1 or 2* at Glu-A1 and the prevalence of subunits 7 + 8 and 5 + 10 at Glu-B1 and Glu-D1 loci, respectively, in the most recent varieties. Dough extensibility was affected by water input during the crop cycle, this relationship being partially explained by the presence of the 5 + 10 HMW glutenin subunit. Fermentation tolerance was improved in the most modern varieties. Collapse during fermentation was avoided only in doughs with a W ≥ 159 J × 10⁻⁴ and a P/L ≥ 0.56 mm H₂O mm⁻¹, levels achieved by most of the modern varieties. The over-strong and unbalanced rheological properties of some modern varieties resulted in highly porous doughs, and no clear advances in dough maximum height during fermentation were attained.     

农药悬乳体系流变学特性研究

研究了两种悬浮稳定剂对40%乙草胺+莠去津+氰草津悬乳剂的流变学特性的影响,发现在该悬乳体系中结合使用无机膨润土和有机黄原胶能增加体系的触变性能和稳定性能,能显著增加体系的粘度、屈服值和稳定度。     

Responses of wheat yield,quality and bread-making properties on the sulphur fertilization

This study presents a versatile influence of sulphur (S) application on winter wheat – beginning with the influence on the grain yield and primary quality indices, followed by the one on the bread-making properties of flour and dough, and ending with the one on the quality indices of baked products. Field experiments were conducted at two locations on haplic Luvisol and calcaric Cambisol during five years. S was given as NS-fertilizers on the background of N100 during wheat tillering. Flour and dough properties for bread-making were determined by using a farinograph Brabender. The baking tests were carried out in laboratory conditions. The influence of S on the grain yield and quality, and bread-making properties of wheat depended on the year and location. As the average of field experiments conducted at two locations, the application of S significantly increased the grain yield (r?=?0.960). The increasing yields were accompanied by decreasing contents of wet gluten (r?=?0.825). However, the significant positive (r?=?0.938) effect of the S application on the Gluten index was revealed, which is a good predictor of the baking quality of wheat flour. The S addition by nitrogen fertilization resulted also in a positive shift of the N:S ratio in grains, which is better for the bread-making quality. The significant positive effects of the S application on the dough stability time (r?=?0.898) and on the farinograph quality number (r?=?0.917) were demonstrated. The loaf volume was significantly (r?=?0.842) increasing under the influence of S. Thus, the application of S in parallel with increasing yields improved several bread-making parameters of wheat.     

Improving the mechanical characteristics of faecal waste in rainbow trout: the influence of fish size and treatment with a non-starch polysaccharide (guar gum)

This study (3 × 2 randomized factorial design) describes differences in the mechanical properties of faeces from rainbow trout of three size classes (small ≈40 g, mid-size ≈150 g, large ≈650 g) and assesses the effects of a non-starch polysaccharide binder (guar gum). Observations made at the macroscopic level were reinforced by rheological measurements of viscosity and elastic modulus. Mid-sized fish excreted mechanically the most stable faeces, roughly twice as stable as those of small fish and three times more stable than faeces from large fish. The addition of 3 g kg⁻¹ of guar gum saw some mechanical characteristics improve by about 700%. Faeces from large- and mid-sized fish were more easily stabilized than those of small fish. Mechanical recovery potential for faecal samples disrupted by water turbulence was determined. Stability differences observed for different fish size had no significant effect but the improvements imparted by guar gum reduced postfiltration effluent load to about 35% for large fish, about 24% for mid-size and about 22% for small fish. Faecal leaching decreased significantly with increasing stability. Guar gum was shown to have significant potential for improving the treatability of fish faecal waste.     

小麦粉面团稳定时间的变化及其稳定性分析

 小麦的面团稳定时间是判别小麦品种类别及其用途的重要指标。本研究针对生产上小麦面团稳定时间变化很大的问题，选用山东省主要推广的12个优质小麦品种（系）为材料，在9个不同的试点上，连续3年进行了面团稳定时间变异及其稳定性分析试验。结果表明，不同品种、不同年份和地点间面团稳定时间的变异系数为24.29～49.60。利用主效可加互作可乘模型（AMMI）对面团稳定时间进行稳定性分析得知，面团稳定时间存在显著的品种和地点间的互作效应，其中品种的固定效应导致的变异最大，品种和地点互作次之，地点（含重复）效应较小。但不同品种与不同试点的交互作用不同，每个品种（系）对试点都有其特殊的适应性。因此，在优质专用小麦产业化种植时，要获得面团稳定时间达到标准的商品粮食，即要选准适宜的品种又要注意适宜的种植区域。