Rates of Shrinkage and Growth of Air Bubbles Entrained in Wheat Flour Dough

The rates of shrinkage at constant temperature, and growth under a temperature rise below 100°C, of bubbles entrained in wheat flour dough were analyzed and compared with those of a bubble in water. The rate of shrinkage of bubbles in flour dough was controlled by the diffusion of dissolved air from the surface of bubbles to the bulk of flour dough. The apparent diffusion coefficient of the dissolved air in wheat flour dough with the water fraction of 0.49 calculated from the shrinkage of bubbles, was (3.2 ± 1.5) × 10^1?1 m²/sec (19°C), and (6.4 ± 2.0) × 10^?11 m²/sec (42°C). However, the growth behavior of bubbles in flour dough under a temperature rise was very different from that predicted from the diffusion theory. The critical radius of bubbles to grow was larger than that estimated from the diffusion theory. The mechanism of growth of bubbles in wheat flour dough, which was different from that of a bubble in water, is a subject that needs to be clarified.     

A Novel Transformation to S-Methyl Phosphorodichloridothiolate and the Fungitoxicity of Diaryl S-Methyl Phosphorothiolates

Prior to an analysis of the shrinkage and growth of air bubbles entrained in wheat flour dough, the shrinkage and growth under a temperature rise of a small bubble in water was analysed for comparison. The rates of shrinkage and growth of the bubble were respectively controlled by the diffusion of under- and over-saturated dissolved air from and into the bubble. The diffusion coefficient of the dissolved air in water calculated from the shrinkage of the bubble was 2.10 × 10^_9m²/sec (17°C), which agrees with the literature value. On the other hand, at below 100°C, the effects on the bubble growth of the expansion of air due to the temperature rise and the increase in the saturation vapor pressure of water were negligibly small. The accompanying air entrained in flour particles suspended in water was much more stable than a free bubble in water. However, the growth under a temperature-rise of a bubble evolved from wheat flour particles was the same as the growth of a bubble in water, if many bubbles did not coexist.     

Analysis of Abscisic Acid in the Brains of Rodents and Ruminants

The surface tension (σ) of batter prepared with one or two of the major ingredients of wheat flour, egg and sucrose was measured by the maximum bubble pressure method. The surface tension of the soft- and hard-wheat flour suspension decreased as the solid content of wheat flour was increased, finally reaching 48.2 and 52.7 dyn/cm, respectively. The surface tension of the wheat flour suspension was lower than that of its supernatant, which suggests that the precipitate reduced the surface tension. Gelatinization of the wheat flour suspension lowered its surface tension. The surface tension of the whole egg dispersion decreased markedly to about 53 dyn/cm as the solid concentration was increased from 0 to 1%, and remained almost constant as the concentration was increased further. This tendency was almost the same as that of the egg yolk dispersion. The surface tension of mixtures of two ingredients such as egg and wheat flour, and egg and sucrose was almost equal to that of the ingredient with the lower surface tension at the same concentration as in the mixture.     

Effect of arabinogalactan isolated from Siberian larch on the baking value of soft wheat flour and bread quality

Using additives of arabinogalactan (AG) isolated from Siberian larch, we examined the soft wheat flour quality and quantity of gluten, physical properties of the dough, and quality of finished bread depending on the quantity of the added polysaccharide. In the case of the addition of 1–3% of AG to flour, its content decreases in the final product. An excess amount of AG inhibits yeast growth, which leads to a decrease in bread quality. The optimum addition of AG to flour is 1%, at which the technological properties of flour and dough do not change significantly, but the quality of bread becomes remarkably better; furthermore, arabinogalactan is fully consumed in the course of bread preparation. The use of AG is recommended in the optimum dose for increasing the quality of baked goods.     

A Spin-Label Study on Lipids in Dough Formed at Various Concentrations of Oxygen

The effect of oxygen on wheat flour lipids during dough mixing was investigated by analysis of the lipid composition and by an ESR technique with a fatty acid spin-label (4,4’-dimethyl-oxazolidine-N-oxyl derivative of 5-ketostearic acid). Dough was prepared in the presence of the spin-label under an atmosphere of air, nitrogen, 95% nitrogen—5% oxygen or oxygen, and the gluten was obtained by washing out the starch. ESR spectra of the spin-label incorporated into the gluten showed decreases in the order parameter, rotational correlation time and activation energy for rotational viscosity with increasing atmospheric oxygen concentration. During dough mixing in oxygen, oxidation of lipids proceeded and bound lipids slightly decreased. These data indicate that modification of lipids by incorporated oxygen leads to an increase in their fluidity and to a decrease in their hydrophobic interaction with protein in dough.     

Two phases of seasonal stem radius variations of Sabina przewalskii Kom. in northwestern China inferred from sub-diurnal shrinkage and expansion patterns

In the National Natural Reserve of the Qilian Mountains, northwest China, automated dendrometers were installed on Qilian juniper (Sabina przewalskii Kom.) in 2010. Here, we present a complete 1-year data series of dendrometer measurements and synchronous meteorological records. The mean daily radius change index curve obtained by first-difference standardization was analyzed. The results indicate strong similarities of stem radius variations among the studied trees. By graphical inspection of sub-diurnal shrinkage and expansion patterns, seasonal stem radius variations could be divided into two general phases. During early winter to spring, daily amplitudes show strong fluctuations, and meteorological data indicate that both air and soil temperatures are positively related to stem radius swelling. From late March to early November 2011, stem radius expansion is negatively related to both air and soil temperatures, as well as to vapor pressure deficit, and positively related to precipitation and soil moisture. We found that the dividing lines between the two phases were strongly linked to the occurrence of a 0?°C daily mean air temperature, indicating that air temperature played an important effect on stem radius variations in this cold and arid environment. During the growing season in 2011, May and June are the most productive months.     

Analysis of dough functionality of flours from transgenic wheat

The rheological properties of flours from five different lines of transgenic wheat that either express or over-express subunits 1Ax1 and 1Dx5 were analyzed by mixograph assays and SDS sedimentation tests. In one case, the over-expression of subunit 1Dx5 resulted in a ca. 2-fold increase in mixing time, associated with a significant improvement in dough strength, and a lower resistance breakdown, suggesting an important increase in dough stability. However, the flour failed to develop properly without mixing with control flour because the rate of mixing was insufficient to develop the dough, i.e., the flour was overstrong. In two wheat transgenic lines, the expression of 1Ax1 and 1Dx5 transgenes, associated with silencing of all the endogenous high-molecular-weight glutenin subunits, resulted in flours with lower mixing time, peak resistance and sedimentation volumes, suggesting a lower gluten strength.     

Fungi in flour and refrigerated dough products

Summary Fungal counts of 19 flour samples and 11 wheat samples from 11 flour mills of the Kansas-Nebraska and Pacific Northwest wheat-growing areas were made over a period of 2 years. In addition, 50 spoiled and 22 fresh samples of refrigerated dough products were examined for their fungal content. Methods for obtaining counts of fungi from flour and refrigerated dough were improved through the use of tetracycline as a bacterial inhibitor. Fungal counts ranged from 85 to 8,100 per gram in flour and from 90 to 1,400 in wheat. Generally, mold counts were higher in the flour than in the wheat. Judging from earlier reports, improved handling of wheat and better milling practices are effecting a gradual reduction in fungal counts in commercial flours. More than 500 fungi were isolated from the flours and doughs and were identified. Except for a few Fungi Imperfecti and Mucorales, the majority of the species from the flours belong in the generaAspergillus andPenicillium. Not only do they belong to these genera, but to specific groups in each. In the genusAspergillus, representatives of theA. candidus, A. glaucus, A. flavus-oryzae, andA. versicolor groups were the only ones present. InPenicillium the series commonly found wereP. cyclopium, P. citrinum, andP. urticae, and the remaining species were scattered among various series. Fungal counts of both fresh and spoiled dough samples were comparatively low. Essentially, the fungal flora of the doughs was a reflection of the flour microflora. Spoilage of the dough products did not appear to be of fungal origin.This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

花后灌水次数对强筋小麦籽粒产量和品质的影响

在防雨池栽培条件下,以2个优质强筋小麦品种（济麦20和藁城8901）为试验材料,研究了花后不同水分供应状况对籽粒产量、籽粒品质（粉质仪参数和面包体积）及其蛋白质组分的影响.结果表明：2个品种的籽粒产量、面粉的面团形成时间、面团稳定时间和制成面包体积均随花后灌水次数的增加呈先升高后降低的趋势;其中,花后灌1水（花后7 d）时藁城8901的籽粒产量最高,花后灌2水（花后7 d+花后14 d）时济麦20的籽粒产量最高;2个品种面粉的面团形成时间、面团稳定时间和制成面包体积均以花后灌1水时最优.单体蛋白含量、不溶性谷蛋白含量、谷蛋白总含量、蛋白质含量以及湿面筋含量也呈现类似的变化趋势.逐步回归分析表明,花后不同水分供应状况下,不溶性谷蛋白含量是影响面团稳定时间的关键因素,谷蛋白总含量与面包体积的变化密切相关.因此,为了保持优质强筋小麦品质的稳定性,水分管理应以改善籽粒蛋白质特别是谷蛋白组分的构成为目标.     

New enzyme-based method for analysis of water-soluble wheat arabinoxylans

Arabinoxylans (AX) are the predominant cell-wall polysaccharides in wheat flour. Water-extractable AX are essential for dough and bread properties and performance. However, there is no specific and accurate way of determining the content and structure of AX. An enzyme-assisted method employing an efficient enzyme mixture for the total hydrolysis of AX was developed in the present work. Enzymatic hydrolysis (EH) is a gentle method during which no unwanted sugar destruction occurs. Following EH, liberated monosaccharides were analysed by gas chromatography (GC) and liquid chromatography using HPAEC-PAD. The results were compared with acid methanolysis (AM) and acid hydrolysis (AH). EH performed better on commercially isolated AX samples than the reference method AM. Its action in the water extract from wheat flour was also more efficient than that of AM and comparable to the efficiency of AH. HPAEC-PAD revealed a significant amount of fructose in the water extract following EH, originating from fructans in wheat flour not detected in the GC analysis. The wheat flour examined contained 0.29% water-extractable AX. The arabinose/xylose ratio was 0.32. The enzyme-based method developed is applicable for comparison of different wheat flours and can be used in evaluating the effect of processing on the content and structure of water-extractable AX.     

Transformation of common wheat (Triticum aestivum L.) with avenin-like b gene improves flour mixing properties

Avenin-like b proteins may contribute to the viscoelastic properties of wheat dough via inter-chain disulphide bonds, due to their rich cysteine residues. In order to clarify the effect of the avenin-like b proteins on the functional properties of wheat flour, the functional and biochemical properties of wheat flour were analyzed in three transgenic wheat lines overexpressing the avenin-like b gene using the sodium dodecyl sulfate sedimentation (SDSS) test, Mixograph and size exclusion-high performance liquid chromatography (SE-HPLC) analysis. The results of the SDSS test and Mixograph analysis demonstrated that the overexpression of avenin-like b proteins in transgenic lines led to significantly increased SDSS volume and improved flour mixing properties. The results of SE-HPLC analysis of the gluten proteins in wheat flour demonstrated that the improvement in transgenic line flour properties was associated with the increased proportion of large polymeric proteins due to the incorporation of overexpressed avenin-like b proteins into the glutenin polymers. These results could help to understand the influence and mechanism of avenin-like b proteins on the functional properties of wheat flour.     

Transformation of wheat straw polysaccharides under dynamic conditions of subcritical autohydrolysis

Transformation of wheat straw polysaccharides under dynamic conditions of subcritical autohydrolysis has been examined at a pressure of 30 MPa in a temperature range of 150—290°C. The dependence of the yield of gaseous, liquid, and solid products on the process temperature has been studied. The formation of liquid products occurs mainly due to the hydrolysis of pentosans and partially of cellulose in a range of 150–200°C. The main components of liquid products are oligo- and monosaccharides. Xylose and arabinose comprise more than 65% of monosaccharides. A temperature rise in a range of 200–290°C is accompanied by a decrease in medium pH, cellulose hydrolysis, and intensive gasification. Glucose predominates in monosaccharides of liquid products isolated at 270°C; a portion of pentoses does not exceed 25% of the total of monosaccharides. The maximal yield of sugars is observed at 200°C and then decreases from 29.6 to 5.3% per straw oven-dry weight at 270°C. A decrease in reactivity of straw cellulose treated at 200°C to enzymatic hydrolysis has been found.     

Overexpression of Avenin-Like b Proteins in Bread Wheat (Triticum aestivum L.) Improves Dough Mixing Properties by Their Incorporation into Glutenin Polymers

Avenin-like b proteins are a small family of wheat storage proteins, each containing 18 or 19 cysteine residues. The role of these proteins, with high numbers of cysteine residues, in determining the functional properties of wheat flour is unclear. In the present study, two transgenic lines of the bread wheat overexpressing avenin-like b gene were generated to investigate the effects of Avenin-like b proteins on dough mixing properties. Sodium dodecyl sulfate sedimentation (SDSS) test and Mixograph analysis of these lines demonstrated that overexpression of Avenin-like b proteins in both transgenic wheat lines significantly increased SDSS volume and improved dough elasticity, mixing tolerance and resistance to extension. These changes were associated with the increased proportion of polymeric proteins due to the incorporation of overexpressed Avenin-like b proteins into the glutenin polymers. The results of this study were critical to confirm the hypothesis that Avenin-like b proteins could be integrated into glutenin polymers by inter-chain disulphide bonds, which could help understand the mechanism behind strengthening wheat dough strength.     

Bubble stimulation efficiency of dinoflagellate bioluminescence

Dinoflagellate bioluminescence , a common source of bioluminescence in coastal waters , is stimulated by flow agitation . Although bubbles are anecdotally known to be stimulatory , the process has never been experimentally investigated . This study quantified the flash response of the bioluminescent dinoflagellate Lingulodinium polyedrum to stimulation by bubbles rising through still seawater . Cells were stimulated by isolated bubbles of 0 . 3–3 mm radii rising at their terminal velocity , and also by bubble clouds containing bubbles of 0 . 06–10 mm radii for different air flow rates . Stimulation efficiency , the proportion of cells producing a flash within the volume of water swept out by a rising bubble , decreased with decreasing bubble radius for radii less than approximately 1 mm . Bubbles smaller than a critical radius in the range 0 . 275–0 . 325 mm did not stimulate a flash response . The fraction of cells stimulated by bubble clouds was proportional to the volume of air in the bubble cloud , with lower stimulation levels observed for clouds with smaller bubbles . An empirical model for bubble cloud stimulation based on the isolated bubble observations successfully reproduced the observed stimulation by bubble clouds for low air flow rates . High air flow rates stimulated more light emission than expected , presumably because of additional fluid shear stress associated with collective buoyancy effects generated by the high air fraction bubble cloud . These results are relevant to bioluminescence stimulation by bubbles in two‐phase flows , such as in ship wakes , breaking waves , and sparged bioreactors . Copyright © 2015 John Wiley & Sons, Ltd.     

Role of cytokinins in the regulation of stomatal conductance of wheat seedlings under conditions of rapidly changing local temperature

The influence of an air temperature increase by 4°C and nutrient solution cooling down to 5 ± 1°C on stomatal conductance and hormone level of seven-day-old wheat (Triticum durum L., cv. Bezenchukskaya 139) seedlings was studied. An elevated air temperature resulted in a rapid rise of stomatal conductance preceded by the increase in the level of cytokinins in leaves. Cooling of the nutrient solution induced gradual stomatal closure along with a decreasing cytokinin level in leaves. Hormone concentration in the xylem sap of wheat seedlings was determined, and the rate of hormone transport from the roots to shoots was calculated. The role of cytokinins in the regulation of stomatal conductance under conditions of local thermal treatments is discussed.     

Use of selected enterococci and Rhizopus oryzae proteases to hydrolyse wheat proteins responsible for celiac disease

Aims:  This work aimed at using a pool of selected enterococci and fungal proteases to hydrolyse wheat gluten during long-time fermentation.
Methods and Results:  A liquid dough made with wheat flour (20% w/w) was fermented with three Enterococcus strains (dough A) or with the combination of enterococci and Rhizopus oryzae proteases (dough B). After 48 h of fermentation, dough A and B had a concentration of water-soluble peptides approximately threefold higher than the chemically acidified dough (CAD), used as the control. The same was found for the concentration of free amino acids, being higher in dough B with respect to dough A. SDS-PAGE analysis showed that albumin and glutenin fractions were partially hydrolysed, while gliadins almost disappeared in dough A and B, as confirmed by two-dimensional electrophoresis, RP-HPLC and R5-ELISA analyses.
Conclusions:  The combined use of enterococci and fungal proteases showed a decrease of the gluten concentration of more than 98% during long-time fermentation.
Significance and Impact of the Study:  The use of the mixture of selected enterococci and R. oryzae proteases should be considered as a potential tool to decrease gluten concentration in foods.     

The effect of seaweed composite flour on the textural properties of dough and bread

Seaweeds as food and seaweed-derived food flavors, colors, and nutrients are attracting considerable commercial attention. In the baking industries, hydrocolloids are of increasing importance as bread making improvers, where their use aims to improve dough handling properties, increase the quality of fresh bread, and extend the shelf life of stored bread. Seaweeds contain a significant amount of soluble polysaccharides and have the potential function as a source of dietary fiber. In this study, red seaweed (Kappaphycus alvarezii) powder was incorporated (2–8 %) with wheat flour and used to produce bread. The effect of seaweed composite flour on dough rheological properties and the quality of bread was investigated using various techniques. Farinograph tests were applied to determine the effect of seaweed powder on the rheological properties of wheat flour dough, while texture profile analysis (TPA) was used to measure the textural properties of dough as well as the final product. The results showed that the additions of seaweed powder (2–8 %) increased the water absorption of the dough. TPA results showed that the addition of seaweed powder decreased stickiness properties. Bread produced with seaweed composite flour showed higher values of firmness.     

Probing structural features of water-insoluble proteins by front-face fluorescence

Front-face fluorescence was used to assess some structural features of proteins in wheat flours, taking advantage of the fact that this technique allowed a direct approach to a number of systems in which most proteins cannot be solubilized without using conditions that strongly modify the structure of proteins in the original material. In this study, we addressed structural changes ensuing from solvation and from mechanical deformation of proteins in wheat flour. Solvation of proteins in the systems under investigation was monitored by taking fluorescence emission spectra of the protein tryptophans (or of protein-bound 1,8-anilino-naphthalene-sulfonate added in appropriate amounts) in mixtures of increasing water content. In separate experiments, changes in overall protein surface hydrophobicity were estimated by titrating flours-mixed with appropriate amounts of water to a dough-like consistency-with increasing concentrations of the fluorescent hydrophobic probe, 1,8-anilino-naphthalene-sulfonate. This approach allowed concomitant determination of the overall binding capacity and of the apparent affinity for the probe of proteins. To test the usefulness of the structural information obtained from these approaches, they were also applied to characterize dough at different levels of mechanical stress, prepared from either wheat flour or semolina.     

Characterisation of a Talaromyces emersonii thermostable enzyme cocktail with applications in wheat dough rheology

In this paper, we report new sequence data for secreted thermostable fungal enzymes from the un-sequenced xylanolytic filamentous fungus Talaromyces emersonii and reveal novel insights on the potential role of enzymes relevant as wheat dough improvers. The presence of known and de novo enzyme sequences were confirmed through NanoLC-ESI-MS/MS and resultant peptide sequences were identified using SWISS PROT databases. The de novo protein sequences were assigned identity based on homology to known fungal proteins. Other proteins were assigned function based on the limited T. emersonii genome coverage. This approach allowed the identification of enzymes with relevance as wheat dough improvers. Rheological examination of wheat dough and wheat flour components treated with the thermostable fungal enzyme cocktail revealed structural alterations that can be extrapolated to the baking process.Thermoactive amylolytic, xylanolytic, glucanolytic, proteolytic and lipolytic enzyme activities were observed. Previously characterized T. emersonii enzymes present included; β-glucosidase, xylan-1,4-β-xyloxidase, acetylxylan esterase, acid trehalase, avenacinase, cellobiohydrolase and endo-glucanase. De novo sequence analysis confirmed peptides as being; α-glucosidase, endo-1,4-β-xylanase, endo-arabinase, endo-glucanase, exo-β-1,3-glucanase, glucanase/cellulase, endopeptidase and lipase/acylhydrolase. Rheology tests using wheat dough and fractioned wheat flour components in conjunction with T. emersonii enzymes show the role of these novel biocatalysts in altering properties of wheat substrates. Enzyme treated wheat flour fractions showed the effects of particular enzymes on appropriate substrates. This proteomic approach combined with rheological characterization is the first such report to the authors’ knowledge.     

Effect of temperature change and aeration on the production of the antifungal peptide antibiotic iturin by Bacillus subtilis NB22 in liquid cultivation

The effects of temperature and air supply on the production of the antifungal lipopeptide antibiotic, iturin by Bacillus subtilis NB22 in a 5-d course of liquid cultivation were investigated on a flask scale. Changing the temperature from 30°C to 25, 37, 42, or 48°C for one day during the 5-d cultivation reduced the amount of iturin producted in comparison with cultivation at a constant 30°C. The temperature on the first day was notably critical. When the air supply was varied by changing the plugs of the shaking flasks, the air supply was also critical on the first day. When cells spent the first day with an inappropriate temperature or air supply, the decrease in iturin production could not be compensated for during the subsequent 4-d cultivation at an adequate temperature and air supply. Although iturin production was significant on the second and third days when the growth of the bacterium had leveled off, the initial conditions severely affected the yield of the product.