Effect of Gaseous Acetic Acid on Dough Rheological and Breadmaking Properties

Breads baked from wheat flours (protein contents 14.1–16.5% at 14.0% mb) that were pretreated with 2–3 mL of gaseous acetic acid per kg of wheat flour, showed maximum bread height and specific volume (cm³/g). Flour-water suspension and the crumb pH values were gradually decreased with increased amounts of acetic acid. Gas generation and dough expansion tests with bread dough showed that the addition of the same amount of acetic acid, which achieved maximum specific volume, also showed the highest rate of gas generation and dough expansion. However, increasing acetic acid decreased these values. Scanning electron microscope (Cryo-SEM) observation showed that the bread dough made from the same acetic acid-treated flour indicated continuum and no cracks in the dough matrix. Evaluation of mixograms showed the decrease of mixing stability with increased acetic acid levels. Viscosity and water binding capacity of flour-water suspensions were sharply increased by the addition of acetic acid at pH 5.0–3.5.     

Effect of Puroindolines on the Breadmaking Properties of Wheat Flour

The role of lipid-binding proteins from wheat seed (puroindolines) on the breadmaking properties of wheat flour was investigated by determining the relationship between breadmaking quality and puroindoline content in samples of 32 wheat cultivars. An inverse relationship was mainly explained by the link between hardness and puroindoline contents. This link is in agreement with previous results which have shown a close structural identity between basic friabilins and puroindolines. Next, the effect of puroindolines in breadmaking was investigated by performing reconstitution experiments with two puroindoline-free hard cultivars of opposite quality (Florence Aurore and Ecrin) as indicated in the screened wheat sample. Addition of 0.1% puroindolines to these flours drastically modified both the rheological properties of doughs and the structure of the bread crumb. Puroindolines are essential to the foaming properties of dough liquor, and a close relationship was found between the fine grain crumb provided by reconstituted flours with puroindolines and the fine structure of corresponding dough liquor foams. The effect of puroindolines on bread volume was mainly related to the rheological properties of wheat doughs.     

Effect of Capsicum Powder on Breadmaking Properties

Fruits of Capsicum species such as paprika (Capsicum annuum cv.), Tomapi (Capsicum annuum subsup. annuum var pomiferum), pimento (Capsicum annuum var. angulosum), and cayenne (Capsicum annuum L.) were blended with wheat flour for breadmaking. Breadmaking properties such as the bread height (mm) and specific volume (cm³/g) are improved by the addition (8%) of any mature fruit of Capsicum species. Among these species, paprika at different growth and maturity stages was used for breadmaking. Breadmaking was enhanced with increasing fruit maturity. Bread height and specific volume on baking with green paprika‐wheat flour were lower than those of controls. When green paprika was heated in an autoclave, the breadmaking properties matched those of controls, which suggested that the impaired breadmaking properties caused by green paprika were due to protease. Size‐exclusion high‐performance liquid chromatography (SE‐HPLC) of flour proteins extracted from wheat flour mixed with heated and unheated paprika also suggested the presence of protease in green paprika. When red paprika was heated under the same conditions, the color changed to brown, and the breadmaking properties did not decrease but increased only slightly. This suggested that carotenoids were not related to the breadmaking properties. A suspension of the heated red paprika was dialyzed against water; after dialysis, the water was concentrated to syrup. The concentrated syrup and dialyzed suspension in the dialysis tube were blended with wheat flour and breadmaking was performed. The results indicated that the improvement of breadmaking properties was due to the dialyzed outer solution, which was heat‐stable and contained LMW materials derived from red paprika.     

Effect of Nitrogen Fertilization on Quantity of Flour Protein Components,Dough Properties,and Breadmaking Quality of Wheat

Three winter wheat varieties with differing breadmaking quality were grown at two locations in two years at 0 or 3 × 60 kg of nitrogen application. The effect of nitrogen on amount of different components of gluten proteins was determined by reverse-phase HPLC. A high amount of nitrogen led generally to a significant increase of total protein content. However, this increase was obvious only for the gluten proteins; albumins and globulins remained nearly unaffected. The effect of increased protein content on gliadin to glutenin (gli-glu) ratio was inconsistent. While increased protein content increased the gli-glu ratio in the variety Capo, the opposite was true for the variety Renan. Gli-glu ratio of the variety Lindos showed no discernible tendency. As total protein content increased, the ratio of low molecular weight (LMW) to high molecular weight (HMW) glutenins decreased consistently, i.e., in all varieties, in both years and locations. Change of LMW to HMW ratio showed a significant negative correlation to sedimentation value and bread volume. There was no consistent change in the ratio between x- and y-type HMW subunits due to fertilization, as could be shown by densitometric measurements on SDS-PAGE gels. This ratio appeared to be dependent on the genotype and has decreased with decreasing quality. The amount of x-type subunits correlated closely with sedimentation value and bread volume. These results suggest that ratio of HMW glutenins, especially x-type subunits, to total protein content could be the best early detectable parameter with high predictive value for breadmaking quality.     

Effect of Outer Bran Layers from Germinated Wheat Grains on Breadmaking Properties

Wheat grains were germinated in the dark at room temperature (24°C) for 1, 2, 3, 5, and 8 days. Germinated wheat grains were pearled in a Waring blender, and the outer bran layers were separated from the pearled grains. Breadmaking was performed with wheat flour and 10% of the outer bran layer. Breadmaking properties (bread height [mm] and specific volume [cm³/g]) were gradually enhanced by blending the germinated outer bran layers, and maximum specific volume was obtained after 5 days of germination. However, the improvement was lost after 8 days of germination. Rapid ViscoAnalyser (RVA) and Brabender Farinograph profiles of wheat flour and outer bran layers (10%) indicated that the maximum decrease of peak viscosity and increase of angle of tail were obtained after 3 and 5 days of germination, respectively. Those changes are presumed to be due to the action of enzymes found in the outer bran layers. Activities of α‐ and β‐amylase, lipase, protease, and xylanase in the outer bran layers were measured, and correlation coefficients (r) between breadmaking properties and peak viscosity (RVA), angle of tail (farinograph), and enzyme activities were calculated. These data suggest that xylanase and α‐amylase activities in the outer bran layers were highly related to the enhancement of the breadmaking properties.     

Effect of the Molecular Weight Distribution of Glutenin Protein from an Extra‐Strong Wheat Flour on Rheological and Breadmaking Properties Through Reconstitution Studies

Ten glutenin fractions were separated by sequential extraction of wheat gluten protein with dilute hydrochloric acid from defatted glutenin‐rich wheat gluten of the Canadian hard red spring wheat (HRSW) cultivar Glenlea. The molecular weight distribution (MWD) of 10 different soluble glutenin fractions was examined by multistacking SDS‐PAGE under nonreduced conditions. Also, the subunit composition of the different glutenin fractions was determined by SDS‐PAGE under reduced conditions. The MWD of the fractions (especially HMW glutenins) varied from fraction to fraction. From early to later fractions, the MWD shifted from low to high. The early extracted fractions contained more LMW glutenin subunits (LMW‐GS) and less HMW glutenin subunits (HMW‐GS). The later extracted fractions and the residue fraction contained much more HMW‐GS (2*, 5, and 7 subunits) than the early extracted fractions. The trend in the amounts of 2*, 5, and 7 subunits in each fraction from low to high matched the extraction solvent sequence containing from lower to higher levels of HCl. The influence of glutenin protein fractions from the extra‐strong mixing cultivar, Glenlea, on the breadmaking quality of the weak HRSW, McVey, was assessed by enriching (by 1%) the McVey base flour with isolated glutenin protein fractions from Glenlea. The mixograph peak development times and loaf volumes of enriched flour were measured in an optimized baking test. The results indicated that the higher content in Glenlea glutenin of HMW‐GS with higher molecular weight, such as 2*, 5, and 7, seem to be the critical factor responsible for the strong mixing properties of Glenlea. Our results confirmed that subunit 7 occurred in the highest quantity of all the HMW‐GS. Therefore, it seems that the greater the content of larger molecular weight glutenin subunits, the larger the glutenin polymers and the stronger the flour.     

Effects of Lactic Acid,Acetic Acid,and Table Salt on Fundamental Rheological Properties of Wheat Dough

The effects of the main metabolites, lactic and acetic acids, from the sourdough process on wheat doughs were tested with a dynamic sinusoidal oscillation test. Tests were done with a controlled stress rheometer. Dough treatment included four mixing times and four rest times before measurement. Phase angle, complex modulus, and viscosity were measured for all doughs at selected rest and mixing times, at frequencies ranging from 0.01–10 Hz. Results for all combinations of mixing and rest times were compared at 10 Hz. Effects of mixing time were most visible immediately after mixing and disappeared partially during rest time. Doughs that contained acid but no salt showed the clearest characteristics of overmixing, expressed by an increase in phase angle and decrease in complex modulus.     

Baking Performance of Durum and Soft Wheat Flour in a Sponge-Dough Breadmaking Procedure

Breadmaking properties were determined for formulations that included durum, soft, and spring wheat flour, using a pound-loaf sponge-dough baking procedure. Up to 60% durum or soft wheat flour plus 10% spring wheat flour could be incorporated at the sponge stage for optimum dough-handling properties. At remix, the dough stage required 30% spring wheat flour. Bread made with 100% spring wheat flour was used as a standard for comparison. Bread made with 60% durum flour exhibited internal crumb color that was slightly yellow. When storing pound bread loaves for 72 hr, crumb moisture content remained unchanged. Crumb firmness and enthalpy increased the most in bread made with 60% soft wheat flour. Crumb firmness increased the least in bread made with 100% spring wheat flour. Enthalpy changed the least in bread made with 60% durum flour. Crumb moisture content was significantly correlated with crumb firmness (r = -0.82) and enthalpy (r = -0.65). However, crumb moisture content was specific for each type of flour and a function of flour water absorption; therefore, these correlations should be interpreted with caution. Crumb firmness and enthalpy were significantly correlated (r = 0.65). Ball-milling flour resulted in an increase in water absorption of ≈2% and in crumb moisture content of ≈0.5% but had no effect on either crumb firmness or enthalpy.     

Effect of Different Wheat Classes and Their Flour Milling Streams on Textural Properties of Flour Tortillas

Wheat flour tortillas were made from flour streams of three wheat cultivars: Jagger hard red winter wheat, 4AT-9900 hard white winter wheat, and Ernie soft red winter wheat. Wheat samples were milled on a Miag experimental mill. Twelve flour streams and one straight-grade flour were obtained. Tortillas were made from each flour stream and the straightgrade flour by the hot-press method. Tortilla stretchability and foldability were evaluated by a texture analyzer and six panelists, respectively. Flour protein and water absorption affected tortilla texture. The foldability evaluated by panelists was positively correlated with flour protein content, farinograph water absorption, and damaged starch (P < 0.05). The 2BK and 3BK streams of hard wheat produced tortillas with strong stretchability and good foldability. Middling streams of hard wheat yielded tortillas with lighter color and less stretchability. Under the conditions tested in this study, soft wheat flours were not good for producing flour tortillas.     

Solvent Retention Capacity Values in Relation to Hard Winter Wheat and Flour Properties and Straight‐Dough Breadmaking Quality

Solvent retention capacity (SRC) was investigated in assessing the end use quality of hard winter wheat (HWW). The four SRC values of 116 HWW flours were determined using 5% lactic acid, 50% sucrose, 5% sodium carbonate, and distilled water. The SRC values were greatly affected by wheat and flour protein contents, and showed significant linear correlations with 1,000‐kernel weight and single kernel weight, size, and hardness. The 5% lactic acid SRC value showed the highest correlation (r = 0.83, P < 0.0001) with straight‐dough bread volume, followed by 50% sucrose, and least by distilled water. We found that the 5% lactic acid SRC value differentiated the quality of protein relating to loaf volume. When we selected a set of flours that had a narrow range of protein content of 12–13% (n = 37) from the 116 flours, flour protein content was not significantly correlated with loaf volume. The 5% lactic acid SRC value, however, showed a significant correlation (r = 0.84, P < 0.0001) with loaf volume. The 5% lactic acid SRC value was significantly correlated with SDS‐sedimentation volume (r = 0.83, P < 0.0001). The SDS‐sedimentation test showed a similar capability to 5% lactic acid SRC, correlating significantly with loaf volume for flours with similar protein content (r = 0.72, P < 0.0001). Prediction models for loaf volume were derived from a series of wheat and flour quality parameters. The inclusion of 5% lactic acid SRC values in the prediction model improved R² = 0.778 and root mean square error (RMSE) of 57.2 from R² = 0.609 and RMSE = 75.6, respectively, from the prediction model developed with the single kernel characterization system (SKCS) and near‐infrared reflectance (NIR) spectroscopy data. The prediction models were tested with three validation sets with different protein ranges and confirmed that the 5% lactic acid SRC test is valuable in predicting the loaf volume of bread from a HWW flour, especially for flours with similar protein contents.     

Significance of Aegilops tauschii Glutenin Genes on Breadmaking Properties of Wheat

The contribution of the diploid wild wheat species Aegilops tauschii (DD) to breadmaking quality was studied using synthetic hexaploid wheats (AABBDD) derived from a common Triticum turgidum var. durum (AABB) and three A. tauschii parental lines. Prolamin alleles of the T. durum and A. tauschii parents are additively expressed in the synthetic hexaploids. Bread loaf volumes (BV) assessed by micro-rapid-mix-test (MRMT) and rheological parameters: gluten index (GI), maximum resistance (RE), SDS-sedimentation (SDSS), dough surface, and other quality characteristics clearly indicate that BV and other breadmaking properties in hexaploids are significantly influenced by glutenin genes of the A. tauschii species.     

Effect of Added Fat on the Rheological Properties of Wheat Flour Doughs

The effect of added fat content on the rheological properties of wheat flour doughs was determined for three different added fat contents (2.5, 5.0, and 7.5%) at 25°C using dynamic mechanical analysis (DMA) and stress relaxation (SR) tests. Frequency sweeps indicated that added fat had a plasticizing effect on G′ and G″ in the rubbery region. SR results were parameterized using a Maxwell model and a Williams-Watts (WW) model. The WW model indicated that each dough could be characterized by just two major relaxation modes, while four elements were needed for the Maxwell model. The average relaxation time for the shorter process was <1 sec and was not affected by added fat. However, the average relaxation time for the longer WW process actually increased from 107 to 261 sec with added fat up to 5%, and then decreased again. Taken together, these results suggest that added fat actually delayed the onset of viscous flow, while simultaneously attenuating the short-time elastic properties of the gluten fraction of the dough. Furthermore, rheological testing over a wide time (frequency) scale was needed to observe the effect of added fat on both the short-time elastic and longer-time viscous behavior of these doughs.     

Quantitative Glutenin Composition from Gel Electrophoresis of Flour Mill Streams and Relationship to Breadmaking Quality

Three samples of Nekota (hard red winter wheat) were milled, and six mill streams were collected from each sample. The 18 mill streams were analyzed separately as well as recombined to form three patent flours. The methods of multistacking (MS)‐SDS‐PAGE and SDS‐PAGE were used to separate the unreduced SDS‐soluble glutenins and the total reduced proteins, respectively. The separated proteins were quantified by densitometry. The quantity of unreduced SDS‐soluble proteins was significantly different among the mill streams at the 4% (largest molecular weight polymeric glutenins) and at the 10 and 12% (smaller molecular weight polymeric glutenins) origins of the MS‐SDS‐PAGE gels. The quantities of total HMW‐GS, LMW‐GS, 2*, 7+9, and 5+10 subunits and the ratio of HMW‐GS to LMW‐GS in polymeric protein samples isolated using preparative MS‐SDS‐PAGE and in total reduced protein extracts were significantly different among mill streams. The quantities of HMW‐GS, LMW‐GS, 2*, 7+9, and 5+10 subunits from total reduced proteins were positively and significantly correlated with loaf volume. The quantities of glutenin subunits (both HMW‐GS and LMW‐GS) from unreduced SDS‐soluble proteins were positively or negatively correlated with loaf volume at the various MS‐SDS‐PAGE gel origins but the levels of correlation were not significant. These results showed that the glutenin protein composition was different among the various mill streams and demonstrated that electrophoretic analysis of the proteins in these fractions is a useful tool for studying the variation in functional properties of flour mill streams.     

Distribution of Protein Composition in Bread Wheat Flour Mill Streams and Relationship to Breadmaking Quality

Wheat protein quantity and composition are important parameters for wheat baking quality. The objective of this study was to use fractionation techniques to separate the proteins of flour mill streams into various protein fractions, to examine the distribution of these protein fractions, and to establish a relationship between protein composition and breadmaking quality. Nine break streams, nine reduction streams, and three patent flours obtained from three samples of Nekota (a hard red winter wheat) were used in this study. A solution of 0.3M NaI + 7.5% 1-propanol was used to separate flour protein into monomeric and polymeric proteins. The protein fractions, including gliadin, albumin+globulin, HMW-GS, and LMW-GS, were precipitated with 0.1M NH₄Ac-MeOH or acetone. The fractions were statistically analyzed for their distribution in the mill streams. The quantities of total flour protein and protein fractions in flour were significantly different among mill streams. The ratio of polymeric to monomeric proteins in break streams was significantly greater than in the reduction streams. The relationship between protein composition and breadmaking quality showed that the quantities of total flour protein, albumin+ globulin, HMW-GS, and LMW-GS in flour were significantly and positively correlated with loaf volume. The ratio of HMW-GS to LMW-GS had little association with loaf volume. The gliadin content in total flour protein was negatively and significantly correlated with loaf volume. These results indicated that the quantity and composition of protein among the mill streams was different, and this resulted in differences in breadmaking quality.     

Effect of Saline Organic Acid Solutions Applied During Wheat Tempering on Flour Functionality

Previously, we showed that tempering with saline organic acid solutions can reduce the aerobic plate count of wheat by as much as 4.3 log CFU/g. The purpose of this study was to evaluate the impact of these tempering solutions on the functional properties of resulting whole grain (WGF) and straight‐grade (SGF) flours. Wheat was tempered to 15.5% moisture by tempering with sterile distilled water (control) or solutions containing NaCl (26% [w/v]) together with organic acid (acetic or lactic 2.5 and 5.0% [v/v]). After milling, fractions were collected and recombined as needed to obtain WGF or SGF. The acid content in WGF was higher than in SGF, indicating limited penetration of the organic acids into the endosperm of the grain. In WGF, the saline organic acid treatments caused a decrease in paste viscosity and bread crumb cell sizes in breads. In SGF, the saline organic acid treatments caused significant changes in paste viscosity and some Mixograph parameters; however, principal components analysis indicated that the treatments did not substantially affect SGF functionality. Thus, WGF was altered by the saline organic acid solutions, whereas SGF functionality was minimally affected by tempering treatments, perhaps because of acids only partially penetrating into the endosperm.     

Calcium Effects on Acetic Acid Toxicity in Rice

Recent soil‐management practices such as no‐tillage and minimal tillage, when applied to the irrigated rice crop, promote changes in soil composition as a result of anaerobic degradation of organic matter. Several short‐chain organic acids are formed, such as acetic acid. The objective of this work was to determine the effect of calcium (Ca) on plant development under stress by acetic acid toxicity. The experiment was conducted in hydroponics by testing different Ca (0.2, 1.0, and 5.0 mmol L^?1) and acetic acid (0 and 2.5 mmol L^?1) concentrations. The variables evaluated were the root system morphological parameters (total length, radius, area, dry‐matter weight, and main root growth), shoot parameters (shoot dry matter, plant height), and concentration and total accumulated nitrogen (N), phosphorus (P), potassium (K), Ca, and magnesium (Mg) in the plants. The growth of the root system and the shoots of rice plants were not affected by the addition of Ca to the treatments containing acetic acid.     

不同干燥方法对栗粉的理化性质与功能特性的影响

以毛板红板栗品种为原料，研究了4种不同干燥方法加工所得栗粉的理化与功能特性，结果表明自然干燥与热风干燥加工成的栗粉在理化和功能特性上差异较小，但自然干燥粉比热风干燥粉具有更好的起泡能力和泡沫稳定性；微波干燥粉比热风干燥有较多的淀粉发生糊化，表现在具有较低的峰粘度、崩解值和回复值，其吸水能力较热风干燥粉大，但起泡能力、泡沫稳定性和复水成泥后的一些质地特征值较热风干燥粉低。高温蒸后热风干燥粉的理化与功能特性与微波干燥粉类似，但有较高的崩解值和较低的回复值。从色泽来看，自然干燥和热风干燥粉比微波干燥和高温蒸后热风干燥的要白，而且有光泽。     

Effect of l‐Cysteine on the Rheological Properties of Wheat Flour

Extrudate expansion of cereal‐based products is largely dependent on the molecular interactions and structural transformations that proteins undergo during extrusion processing. Such changes strongly influence the characteristic rheological properties of the melt. It is possible to modify rheological properties of wheat flour during extrusion processing, in particular shear viscosity, with cysteine. The objective of this work was to further develop an understanding of the molecular interactions and structural transformations of wheat flour from dynamic oscillatory rheological measurements. Temperature and frequency sweeps were conducted in the linear viscoelastic range of the material. Changes in the storage modulus (G′), the loss modulus (G″) and the loss tangent (tan δ) of 25% moisture wheat flour disks as a function of cysteine concentration (0–0.75%) were monitored. Molecular weight between cross‐links (M_c) and the number of cross‐links (N_c) per glutenin molecule were determined from frequency sweep data. Increasing cysteine concentration broke cross‐links by decreasing G′ maximum and increasing tan δ values. Molecular weight between cross‐links increased and the number of cross‐links decreased. G′ values from temperature sweeps showed a similar trend. This information leads to a better understanding of the viscoelastic behavior of wheat flour doughs during extrusion cooking and elucidation of protein‐protein reaction mechanisms and other interactions in extruded cereal‐based snack foods.     

Physicochemical Properties of Oat Varieties and Their Potential for Breadmaking

The breadmaking potential of six oat varieties was compared with and related to their physicochemical properties. The most significant differences in the bread characteristics were found in the crumb structure. The varieties Buggy, Energie, and Zorro resulted in good bread quality with an even gas‐cell distribution characterized by a high number of relatively small pores. In contrast, Typhon, Ivory, and Nord 08/311 each had a large hole in the center of the crumb and accordingly poor quality. Breads differed little in specific volume, bake loss, and density. Rheological analysis revealed positive effects of low batter resistance to deformation on oat bread quality. On the basis of the physicochemical characterization, protein and fat contents were identified as key factors responsible for differences observed in bread quality, provided that starch damage and water‐hydration capacity were low. Additionally, high setback and final viscosity, as determined by Rapid Visco Analyser (RVA) analysis, positively affected oat bread quality. High α‐amylase activity was found to influence negatively the breadmaking performance of oats. Overall, protein, fat, dietary fiber content, starch pasting properties, and α‐amylase activity were responsible for the breadmaking properties of oat varieties.     

Use of Two Endoxylanases with Different Substrate Selectivity for Understanding Arabinoxylan Functionality in Wheat Flour Breadmaking

A Bacillus subtilis endoxylanase (XBS) with a strong selectivity for hydrolysis of water‐unextractable arabinoxylan (WU‐AX) and an Aspergillus aculeatus endoxylanase (XAA) with a strong selectivity for hydrolysis of water‐extractable arabinoxylan (WE‐AX) were used in straight‐dough breadmaking with two European wheat flours. Dough, fermented dough, and bread characteristics with different levels of enzyme addition were evaluated with a strong emphasis on the arabinoxylan (AX) population. The WU‐AX solubilized by XBS during breadmaking were mainly released during mixing and had higher molecular weight, in contrast to their counterparts solubilized by XAA, which were mainly released during fermentation and had lower molecular weight. This coincided with increased loaf volume with XBS and a negative to positive loaf volume response with XAA. Bread firmness and dough extract viscosity also were affected by endoxylanase addition. Results confirmed that WU‐AX are detrimental for breadmaking, while WE‐AX and solubilized AX with medium to high molecular weight have a positive impact on loaf volume.