Reduced Gelatinization,Hydrolysis, and Digestibility in Whole Wheat Bread in Comparison to White Bread

Wheat, an important crop in North Dakota and the United States, is often used for bread. Health concerns related to chronic diseases have caused a shift toward consumption of whole wheat bread. There has been some indication that the rate and amount of starch digestibility of whole wheat breads may be lower than for their refined flour counterparts. This research investigated the components of whole wheat bread that may reduce starch digestibility and impact nutritional quality. Six formulations of flour were used, which included two refined flours, two whole wheat flours, and two whole wheat flours with added starch. The starch was added to whole wheat flours to increase the starch level to that of the refined flour so that we can determine whether or not the dilution of the starch in whole wheat bread was a factor in lowering the estimated glycemic index (eGI) of whole wheat bread. White and whole wheat flours and breads were evaluated for chemical composition, baking quality by 1 , and eGI by the Englyst assay. Whole wheat breads had significantly (P < 0.05) higher mineral, protein, arabinoxylan, and phenolic acid contents, as well as significantly (P < 0.05) lower eGI. The starch molecular weight was also significantly (P < 0.05) higher for whole wheat and whole wheat + starch breads compared with white breads. The eGIs of refined flour breads were 93.1 and 92.7, whereas the eGIs of whole wheat and whole wheat + starch breads ranged from 83.5 to 85.1. Overall, several factors in the whole wheat bread composition can be found to affect the quality and starch hydrolysis.     

Factors Controlling Gas Cell Failure in Bread Dough

Stress relaxation in the wall of a gas bubble, as measured by the alveograph, was used to study surface tension at the gas-dough interface of doughs from flours producing differing bread crumb grains. The surface tensions in the various wheat flour doughs were not different. Dough rheological properties, as measured by both dynamic oscillatory rheometry and lubricated uniaxial compression, were not different for doughs made from wheat flours that gave breads with different crumb grains. However, when the effect of starch granule size on gas cell wall stability was tested, the presence of a greater proportion of large starch granules in wheat flour dough was sufficient to result in gas cell coalescence and open crumb grain in the final baked product. This suggests that starch granule size is at least one of the factors that affects the crumb grain of bread.     

Evaluation of Various Baking Methods for Polished Wheat Flours

Flour qualities of polished wheat flours of three fractions, C‐1 (100–90%), C‐5 (60–50%), and C‐8 (30–0%), obtained from hard‐type wheat grain were used for the evaluation of four kinds of baking methods: optimized straight (OSM), long fermentation (LFM), sponge‐dough (SDM) and no‐time (NTM) methods. The dough stability of C‐5 in farinograph mixing was excellent and the maturity of polished flour doughs during storage in extensigraph was more improved than those of the commercial wheat flour (CW). There were no significant differences in the viscoelastic properties of CW dough after mixing, regardless of the baking method, while those of polished flour doughs were changed by the baking method; this tendency became clear after fermentation. The polished flours could make a better gluten structure in the dough samples after mixing or fermentation using LFM and SDM, as compared with other baking methods. Baking qualities such as specific volume and storage properties of breads from all polished flours made with SDM increased more than with other methods. In addition, viscoelastic properties of C‐5 and C‐8 doughs fermented by SDM were similar to those of CW, and the C‐5 breadcrumb showed softness similar to that of the CW. Also, SDM could make C‐5 bread with significantly higher elasticity and cohesiveness after storage for five days when compared with CW bread. Therefore, SDM with long fermentation, as compared with other baking methods, was considered suitable for use with polished flours to give better effects on dough properties during fermentation, resulting in more favorable bread qualities.     

Creep‐Recovery of Wheat Flour Doughs and Relationship to Other Physical Dough Tests and Breadmaking Performance

Measurements of creep‐recovery of flour‐water doughs were made using a dynamic mechanical analyzer (DMA) in a compression mode with an applied probe force of 50 mN. A series of wheat flour and blend samples with various breadmaking potentials were tested at a fixed water absorption of 54% and farinograph optimum water absorption, respectively. The flour‐water doughs exhibited a typical creep‐recovery behavior of a noncross‐linked viscoelastic material varying in some parameters with flour properties. The maximum recovery strain of doughs with a fixed water absorption of 54% was highly correlated (r = 0.939) to bread loaf volume. Wheat flours with a large bread volume exhibited greater dough recovery strain. However, there was no correlation (r = 0.122) between maximum creep strain and baking volume. The maximum recovery strain of flour‐water doughs also was correlated to some of the parameters provided by mixograph, farinograph, and TA‐XT2 extension.     

Staling Effects When Adding Low Amounts of Normal and Heat‐Treated Barley Flour to a Wheat Bread

The properties of a white wheat bread could be changed by adding normal or heat‐treated barley flour in small amounts (2 and 4%) to a white wheat bread recipe. Differences regarding gelatinization as well as retrogradation properties were found when analyzing the two flours in model systems. The heat‐treated flour was fully gelatinized due to prior time, temperature, and pressure treatment and could therefore absorb larger amounts of water than the other flours. In gelatinized model systems with 40% flour (dwb), the heat‐treated barley flour contained less retrograded amylopectin as compared with normal barley flour after storage for up to 14 days, whereas no differences were found with 20% flour (dwb). However, stored breads showed an increased retrogradation of amylopectin (as measured by differential scanning calorimetry [DSC]) when 2% pretreated barley flour was added as compared with addition of 2% normal barley flour. On the other hand, there were no significant differences at the 4% level. Addition of either of the barley flours resulted in less firm breads during storage as compared with the control breads. Increased water absorption in barley flour and thus increased water content in the breads or different water‐binding capacities of the flour blends could explain these results. The present study indicated that water had a stronger influence on bread firmness than the retrogradation of amylopectin. This conclusion was based on breads with pretreated barley flour being less firm than breads with normal barley flour, although the retrogradation, as determined by DSC, was higher.     

Dough Properties and Bread Quality of Wheat–Barley Composite Flour as Affected by β‐Glucanase

Barley is rich in nutritionally positive compounds, but the quality of bread made of wheat–barley composite flours is impaired when a high percentage of barley is used in the mixture. A number of enzymes have been reported to be useful additives in breadmaking. However, the effect of β‐glucanase on breadmaking has scarcely been investigated. In this paper, the influence of different levels (0.02, 0.04, 0.06, and 0.08%, based on composite flour) of β‐glucanase (100,000 U/g) on the properties of dough and bread from 70% wheat, 30% barley composite flour were studied. Although dough development time, dough stability, and protein weakening value decreased after β‐glucanase addition, dough properties such as softness and elasticity as well as bread microstructure were improved compared with the control dough. β‐Glucanase also significantly improved the volume, texture, and shelf life of wheat–barley composite breads. The use of an optimal enzyme concentration (0.04%) increased specific volume (57.5%) and springiness (21%), and it reduced crumb firmness (74%) and staling rate. Bread with added β‐glucanase had a better taste, softness, and overall acceptability of sensory characteristics compared with the control bread. Moreover, the quality of wheat–barley composite bread after addition of 0.04% β‐glucanase was nearly equal to the quality of pure wheat bread. These results indicate that dough rheological characteristics and bread quality of wheat–barley composite flour can be improved by adding a distinct level of β‐glucanase.     

Mixing Properties,Baking Potential,and Functionality Changes in Storage Proteins During Dough Development of Triticale‐Wheat Flour Blends

Flours from advanced lines or cultivars of six triticales and two prime hard wheats, along with triticale‐wheat blends, were investigated for mixing, extension (excluding blends), and baking properties using microscale testing. Percentage total polymeric protein (PPP) and percentage unextractable polymeric protein (UPP) of flours and doughs, including blends, mixed to optimal dough development were estimated using size‐exclusion HPLC to determine the changes in protein solubility and association with blend composition (BC), mixing properties, and loaf height. Each triticale was blended with flours of each of the two wheat cultivars (Hartog and Sunco) at 0, 30, 40, 50, 60, 70, and 100% of wheat flour. Nonlinear relationships between BC and mixograph parameters (mixing time [MT], bandwidth at peak resistance [BWPR], and resistance breakdown [RBD]) were observed. A linear relationship between BC and peak resistance (PR) was predominant. PPP of triticale flours was mostly higher than PPP of wheat cultivars. UPP of all triticales was significantly lower than wheat cultivars. PPP of freeze‐dried doughs was mostly nonsignificant across the blends and showed a curvilinear relationship with BC. The deviations from linearity of MT and PPP were higher in triticale‐Sunco blends than in triticale‐Hartog blends. UPP of blends was closer to or lower than the lower component in the blend. The deviations from linearity for MT and UPP were greater in triticale‐Hartog blends than triticale‐Sunco blends. A highly significant correlation (P < 0.001) was observed between BWPR and loaf height. This suggested that BWPR in triticale‐wheat flour blends could be successfully used for the prediction of loaf height. Triticale flour could be substituted for wheat flour up to 50% in the blend without drastically affecting bread quality. Dough properties of triticale‐wheat flour blends were highly cultivar specific and dependent on blend composition. This strongly suggested that any flour blend must be tested at the desired blend composition.     

Relationships Between Gluten Rheological Properties and Hearth Loaf Characteristics

The rheological properties of fresh gluten in small amplitude oscillation in shear (SAOS) and creep recovery after short application of stress was related to the hearth breadbaking performance of wheat flours using the multivariate statistics partial least squares (PLS) regression. The picture was completed by dough mixing and extensional properties, flour protein size distribution determined by SE‐HPLC, and high molecular weight glutenin subunit (HMW‐GS) composition. The sample set comprised 20 wheat cultivars grown at two different levels of nitrogen fertilizer in one location. Flours yielding stiffer and more elastic glutens, with higher elastic and viscous moduli (G′ and G″) and lower tan δ values in SAOS, gave doughs that were better able to retain their shape during proving and baking, resulting in breads of high form ratios. Creep recovery measurements after short application of stress showed that glutens from flours of good breadmaking quality had high relative elastic recovery. The nitrogen fertilizer level affected the protein size distribution by an increase in monomeric proteins (gliadins), which gave glutens of higher tan δ and flatter bread loaves (lower form ratio).     

Effect of spelt wheat flour and kernel on bread composition and nutritional characteristics

Spelt wheat seeds (Triticum aestivum subsp. spelta cv. Ostro) were used to obtain white spelt flour (64.5% yield), wholemeal spelt flour (100% yield), and scalded spelt wheat kernels. From these materials, white spelt wheat bread (WSB), wholemeal spelt wheat bread (WMSB), and spelt wheat bread with scalded spelt wheat kernels (SSKB) were made and were compared to the reference white wheat bread (WWB). The spelt wheat flours and breads contained more proteins in comparison to wheat flour and bread. Among the samples the highest rate of starch hydrolysis was noticed in WSB. During the first 30 min of incubation this particular bread was shown to have significantly more (P < 0.05) rapidly digestible starch than the WMSB and later on also more starch than in WWB and SSKB, respectively. The WMSB had the lowest hydrolysis index (HI = 95.7). However, the result did not differ significantly from that in the reference common wheat bread. On the other hand, the most refined spelt wheat flour resulted in a bread product (WSB) that was statistically withdrawn (P < 0.05) as one with the highest HI (112.6).     

Effect of Proofing Time and Wheat Flour Strength on Bleaching,Sensory Characteristics,and Volume of French Breads with Added Soybean Lipoxygenase

Soybean lipoxygenase addition in wheat bread doughs is widely used to improve the crumb color and rheology but little is known about the variability of the activity of lipoxygenase under diverse breadmaking conditions. Thus the objective of this study was to evaluate how soybean lipoxygenase can affect bleaching, volume, and sensory characteristics of French breads when proofing time and wheat flour strength varies. A 3-factor Box-Behnken design was used in this study containing one block and three independent variables or factors designated by exogenous lipoxygenase activity (x₁ = 0–71 unit/μg of protein), wheat flour deformation energy (x₂ = 231–258 × 10^–4 J), and proofing time (x₃ = 2–6 hr). Breads were randomly prepared and all assays were repeated three times. Specific volume (from 5.8 ± 0.4 to 9.9 ± 0.4 cm³/g), sensory quality (from 5.2 ± 0.8 to 8.3 ± 0.6), and yellow hue (from 12.6 ± 0.5 to 16.2 ± 0.3) significantly changed (P < 0.01) among the treatments. Specific volume of the breads increased with higher values of wheat flour strength and proofing time (ŷ_vs = 7.5 + 0.9 x₂ + 1.2 x₃ +0.5 x₂x₃). Sensory quality improved at higher values of wheat flour strength and shorter proofing time (ŷ_sq = 7.8 + 0.7 x₂ – 0.2 x₃ – 0.4 x₂² – 0.6x₃² + 0.5 x₂x₃), while lower and more desirable values of yellow hue were achieved at longer proofing time, higher activity of lipoxygenase, and using stronger wheat flours (ŷ_b = 13.7 – 1.2 x₁ – 0.5 x₂ – 0.2 x₃ + 1.0 x₁² – 0.3 x₁x₂). All regression models showed a good fitness to the experimental data (lack-of-fit P > 0.05) and the difference between predicted and observed values were also not significant (P < 0.05). Our results suggested that proofing time and wheat flour strength have a greater effect on volume and sensory quality of French breads than soybean lipoxygenase. However, the bleaching effect of this enzyme showed positive interaction with proofing time and wheat flour strength, suggesting its application even when strong wheat flours are used for the manufacture of French breads.     

Fermentation Reduces Free Asparagine in Dough and Acrylamide Content in Bread

Free asparagine is an important precursor for acrylamide in cereal products. The content of free asparagine was determined in 11 milling fractions from wheat and rye. Whole grain wheat flour contained 0.5 g/kg and whole grain rye flour 1.1 g/kg. The lowest content was found in sifted wheat flour (0.2 g/kg). Wheat germ had the highest content (4.9 g/kg). Fermentation (baker's yeast or baker's yeast and sourdough) of doughs made with the different milling fractions was performed to investigate whether the content of free asparagine was reduced by this process. In general, most of the asparagine was utilized after 2 hr of fermentation with yeast. Sourdough fermentation, on the other hand, did not reduce the content of free asparagineas efficiently but had a strong negative impact on asparagine utilization by yeast. This indicates that this type of fermentation may result in breads with higher acrylamide content than in breads fermented with yeast only. The effect of fermentation time on acrylamide formation inyeast‐leavened bread was studied in a model system. Doughs (sifted wheat flour with whole grain wheat flour or rye bran) were fermented for a short (15+15 min) or a long time (180+180 min). Compared with short fermentation time, longer fermentation reduced acrylamide content in bread made with whole grain wheat 87%. For breads made with rye bran, the corresponding reduction was 77%. Hence, extensive fermentation with yeast may be one possible way to reduce acrylamide content in bread.     

Antioxidant contents and antioxidative properties of traditional rye breads

The purpose of this research was to find out the effect of flour extraction rate on the antioxidative properties of traditional rye bread and then to compare the bioactive compounds content and antioxidant properties of rye breads with commercial wheat roll. Four types of rye flour with different extraction rates of 100 (whole meal dark flour), 95 (brown flour), 90 (brown flour), and 70% (light flour) originated from Warko rye cultivar were used for traditional bread baking with sourdough fermentation. Four types of the respective rye breads were analyzed for their potentially beneficial components, including tocopherols and tocotrienols, total phenolics and flavonoids, reduced glutathione, and inositol hexaphosphates. Moreover, the phenolic acids profile was provided. The Trolox equivalent antioxidant capacity (TEAC) of the breads was evaluated using free radical scavenging activities of 80% methanol extracts against ABTS*+ radical cation (ABTS radical cation decolorization method) whereas radical scavenging activity (RSA) was determined against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*). The superoxide dismutase-like activity (SOD-like activity) was evaluated as free radical scavenging activities of PBS extracts against superoxide anion radicals (O2*-). The results were compared to whole meal rye bread as well as to wheat roll taken as representative example of wheat based bakery product. The studies showed that flour extraction rates strongly affected the content of bioactive compounds and antioxidative properties of traditionally baked rye breads. The incorporation of the rye flours with extraction rates from 100 down to 70% in the formulation caused decrease in tocopherol (T), tocotrienol (T3), inositol hexaphosphate (IP6), and phenolic compound (TPC) contents in rye breads. No changes in reduced glutathione (GSH) contents were noted between each type of rye bread. A significant decrease in Trolox equivalent antioxidant capacity and radical DDPH scavenging activity was also found in bread formulated on flour with an extraction rate of 70% in comparison to the breads formulated on flour with extraction rates from 100 to 90%. The highest SOD-like activity was noted for rye bread formulated on flour with an extraction rate of 70%. The four types of rye breads showed better antioxidative properties and higher antioxidant contents when compared to wheat roll with one exception made to tocopherols and tocotrienols.     

Characteristics of Noodles and Bread Prepared from Double‐Null Partial Waxy Wheat

Double‐null partial waxy wheat (Triticum aestivum L.) flours were used for isolation of starch and preparation of white salted noodles and pan bread. Starch characteristics, textural properties of cooked noodles, and staling properties of bread during storage were determined and compared with those of wheat flours with regular amylose content. Starches isolated from double‐null partial waxy wheat flours contained 15.4–18.9% amylose and exhibited higher peak viscosity than starches of single‐null partial waxy and regular wheat flours, which contained 22.7–25.8% amylose. Despite higher protein content, double‐null partial waxy wheat flours, produced softer, more cohesive and less adhesive noodles than soft white wheat flours. With incorporation of partial waxy prime starches, noodles produced from reconstituted soft white wheat flours became softer, less adhesive, and more cohesive, indicating that partial waxy starches of low amylose content are responsible for the improvement of cooked white salted noodle texture. Partial waxy wheat flours with >15.1% protein produced bread of larger loaf volume and softer bread crumb even after storage than did the hard red spring wheat flour of 15.3% protein. Regardless of whether malt was used, bread baked from double‐null partial waxy wheat flours exhibited a slower firming rate during storage than bread baked from HRS wheat flour.     

Factors Influencing Yeast Fermentation and the Effect of LMW Sugars and Yeast Fermentation on Hearth Bread Quality

The purpose of this study was to investigate how wheat cultivar, growth location, type of mill, LMW sugar composition of wheat flours, mixing time, and type of mixer affected yeast fermentation. Also studied was the effect of yeast fermentation and LMW sugar composition on hearth bread quality. To achieve this, 36 different flours were produced from two different mills using six different wheat cultivars grown at three locations. Yeast fermentation in doughs, measured as gas production, was determined using realtime pressure measurements and GasSmart software. A short mixograph mixing or spatula mixing was not efficient enough to rehydrate instant dry yeast. Compressed yeast and a short mixing time were enough to reach maximum fermentation rate. Maximum pressure after 210 min of fermentation was higher for instant dry yeast than for compressed yeast. Wheat cultivar and growth location had a significant effect on LMW sugar composition. Wheat cultivar, growth location, and type of mill used significantly affected pressure curve parameters. Oligosaccharides and damaged starch were positively correlated, and ash content and flour yield were negatively correlated with pressure curve parameters. Hearth bread characteristic crumb structure was positively correlated with all pressure curve characteristics except fast fermentation rate. Increased levels of mono‐ and disaccharides in wheat flour gave hearth breads with a more round shape.     

Effects of Transglutaminase Enzyme on Fundamental Rheological Properties of Sound and Bug‐Damaged Wheat Flour Doughs

Transglutaminase (TG) catalyzes the formation of nondisulfide covalent crosslinks between peptide‐bound glutaminyl residues and ∊‐amino groups of lysine residues in proteins. Crosslinks among wheat gluten proteins by TG are of particular interest because of their high glutamine content. Depolymerization of wheat gluten proteins by proteolytic enzymes associated with bug damage causes rapid deterioration of dough properties and bread quality. The aim of the present study was to investigate the possibility of using TG to regain gluten strength adversely affected by wheat bug proteases. A heavily bug‐damaged (Eurygaster spp.) wheat flour was blended with sound cv. Augusta or cv. Sharpshooter flours. Dynamic rheological measurements, involving a frequency sweep at a fixed shear stress, were performed after 0, 30, and 60 min of incubation on doughs made from sound or blended flour samples. The complex moduli (G* values) of Augusta and Sharpshooter doughs blended with 10% bug‐damaged flour decreased significantly after 30 min of incubation. These dough samples were extremely soft and sticky and impossible to handle for testing purposes after 60 min of incubation. To test the possibility of using TG to counteract the hydrolyzing effect of bug proteases on gluten proteins, TG was added to the flour blends. The G* values of TG‐treated sound Augusta or Sharpshooter doughs increased significantly after 60 min of incubation. The G* values of the Augusta or Sharpshooter doughs blended with bug‐damaged flour increased significantly rather than decreased after 30 and 60 min of incubation when TG was included in the dough formulation. This indicates that the TG enzyme substantially rebuilds structure of dough hydrolyzed by wheat bug protease enzymes.     

Formation of Oligosaccharides and Polysaccharides by Lactobacillus reuteri LTH5448 and Weissella cibaria 10M in Sorghum Sourdoughs

Gluten‐free breads, which are composed of gluten‐free flours, starch, and hydrocolloids, differ from wheat and rye breads in relation to texture, volume, and crumb structure. Moreover, the dietary fiber content is lower compared with wheat or rye breads. Cereal isolates of lactic acid bacteria frequently produce oligo‐ and homopolysaccharides from sucrose, which can improve the nutritional and technological properties of gluten‐free breads as prebiotic carbohydrates and hydrocolloids, respectively. Sorghum sourdough was fermented with Lactobacillus reuteri LTH5448 or Weissella cibaria 10M, which synthesize fructooligosaccharides (FOS) and levan, and isomaltooligosaccharides and dextran, respectively. The gluten‐free bread was produced with 14% sourdough addition. L. reuteri LTH5448 formed FOS and 1.5 g of levan/kg DM in quinoa sourdoughs. FOS were digested by the baker's yeast during proofing, and the levan could be qualitatively detected in the bread. W. cibaria 10M produced >60 g of isomaltooligosaccharides/kg DM and 0.6 g of dextran/kg DM, which could still be detected in the bread. Breads prepared with W. cibaria 10M were less firm compared with breads prepared with L. reuteri LTH5448 or a FOS and levan‐negative mutant of L. reuteri LTH5448. The addition of sourdoughs fermented with oligo‐ and polysaccharide forming starter cultures can increase the content of prebiotic oligosaccharides in gluten‐free breads.     

Fortification of Bread with Hulls and Cotyledon Fibers Isolated from Peas,Lentils, and Chickpeas

Bread was prepared from wheat flour and wheat flour fortified with either 3, 5, and 7% legume hulls or insoluble cotyledon fibers, or with 1, 3, and 5% soluble cotyledon fibers isolated from pea, lentil, and chickpea flours. Incorporation of hulls or insoluble fibers resulted in increases in dough water absorption by 2–16% and increases in mixing time of dough by 22–147 sec. Addition of soluble fiber resulted in decreases in water absorption as the substitution rate increased and similar mixing times to the control dough. Loaf weights of breads containing hulls or insoluble fibers were generally higher than that of control bread at 149.4–166.5 g. However, the loaf volume of breads fortified with legume hulls and fibers (685–1,010 mL) was lower than that of the control bread (1,021 mL). Breads containing soluble fibers were more attractive in terms of crumb uniformity and color than breads containing either hulls or insoluble fibers. Breads fortified with legume hulls and fibers were higher in moisture content than control bread regardless of the type, source, or fortification rate. Bread fortified with up to 7% hulls or insoluble cotyledon fibers or up to 3% soluble cotyledon fibers, with the exception of 7% insoluble pea fiber, exhibited similar firmness after seven days of storage compared with the control bread, despite their smaller loaf volume. Breads containing hull fibers exhibited the lowest starch transition enthalpies as determined by DSC after seven days of storage, while the starch transition enthalpies of breads containing added soluble or insoluble fiber were not significantly different from the control bread.     

Effects of Fermentation and Baking of Whole Wheat and Whole Rye Sourdough Breads on Cereal Alkylresorcinols

Alkylresorcinol (AR) content was determined in multiple-stage whole wheat and whole rye flour sours, as well as in whole wheat and whole rye flour doughs and breads. AR content decreased considerably during fermentation and baking. AR content was reduced by 20 and 46%, respectively, at the end of sourdough starter fermentation of whole wheat and whole rye flour sours. AR content, which was 512 and 210 μg/g in whole rye and whole wheat flour doughs, respectively, was 30 and 0 μg/g, respectively, after baking of breads. Synthetic AR added at different levels to doughs was also greatly reduced during fermentation and baking.     

Effect of Zinc and Aluminum Ions in Breadmaking

Zinc and aluminum ions as chloride or sulfate salts at 50–500 ppm metal ion (flour basis) had no detrimental effect on fermentation of yeastleavened dough. Increased mixing times (≈10–50%) due to addition of aqueous solutions of zinc (250–500 ppm) or aluminum (150–250 ppm) ions to a bread formula was overcome by withholding salt until the final mixing stage. Breads made from commercial flours (12.5% protein) containing zinc (250–500 ppm) or aluminum (150–250 ppm) ions and no oxidant had improved loaf volume and crumb grain when compared with control bread, and no off-taste. Additionally, breads with added zinc or aluminum had better crumb grains and slower firming rates when compared with breads containing optimum l -ascorbic acid (50 ppm) or potassium bromate (20 ppm). Breads made from commercial flours (11.1% protein) and three laboratory flours (11.4–13.6% protein) containing zinc (250 ppm) or aluminum (150 ppm) ions also had improved loaf volumes and crumb grains. Zinc or aluminum ions in combination with l -ascorbic acid, but not potassium bromate, had a detrimental effect on bread quality. Scanning electron microscopy of freeze-dried bread doughs revealed that zinc and aluminum ions enhanced the film-coating property of gluten. One serving (one slice, 28 g) of bread made with 250 ppm zinc ion would provide 25% of the adult recommended dietary allowance of zinc.     

Dough and Baking Properties of High‐Amylose and Waxy Wheat Flours

The dough properties and baking qualities of a novel high‐amylose wheat flour (HAWF) and a waxy wheat flour (WWF) (both Triticum aestivum L.) were investigated by comparing them with common wheat flours. HAWF and WWF had more dietary fiber than Chinese Spring flour (CSF), a nonwaxy wheat flour. Also, HAWF contained larger amounts of lipids and proteins than WWF and CSF. There were significant differences in the amylose and amylopectin contents among all samples tested. Farinograph data showed water absorptions of HAWF and WWF were significantly higher than that of CSF, and both flours showed poorer flour qualities than CSF. The dough of WWF was weaker and less stable than that of CSF, whereas HAWF produced a harder and more viscous dough than CSF. Differential scanning calorimetry data showed that starch in HAWF dough gelatinized at a lower temperature in the baking process than the starches in doughs of WWF and CSF. The starch in a WWF suspension had a larger enthalpy of gelatinization than those in HAWF and CSF suspensions. Amylograph data showed that the WWF starch gelatinized faster and had a higher viscosity than that in CSF. The loaves made from WWF and CSF were significantly larger than the loaves made from HAWF. However, the appearance of bread baked with WWF and HAWF was inferior to the appearance of bread baked with CSF. Bread made with WWF became softer than the bread made with CSF after storage, and reheating was more effective in refreshing WWF bread than CSF bread. Moreover, clear differences in dough and bread samples were revealed by scanning electron microscopy. These differences might have some effect on dough and baking qualities.