Restoration of Breadmaking Properties to Frozen Dough by Addition of Sugar and Yeast and Subsequent Processing

We prepared bread dough A (a mixture of wheat flour, sugar, salt, and water), bread dough B (a mixture of bread dough A and yeast), and bread dough C (first‐proofed, molded, and second‐proofed bread dough B) and froze them at –20°C for six days. They were thawed at 4°C for 16 hr and subjected to their breadmaking processes. The results indicated that breadmaking properties (bread height [mm] and specific volume [cm³/g]) after bread dough A and B processes were the same as those of control bread dough (unfrozen dough). However, in the case of bread dough C, the resulting bread showed depression of the properties. The amount of centrifuged liquid from thawed bread dough C increased. Sugar was added to thawed bread dough C (bread dough C‐1), and then yeast was further added to bread dough C‐1 (bread dough C‐2), and they were subjected to the breadmaking process. The results showed that the breadmaking properties of bread dough C‐2 were the same as those of the control. It was further found that when the first proof step in the bread dough C‐2 process was omitted, the breadmaking properties were depressed. Frozen and thawed bread dough C was packed into a plastic tube, and extension of the dough was compared with that of control dough under reduced pressure. Bread dough C extended to 50 mm, compared with 70 mm for control dough. First proof, mold, and second proof steps of dough C‐2 caused it to extend to the same height as control dough. It was concluded that the increased amount of the separated liquid in thawed dough C caused depression of breadmaking properties resulting from lack of water in the appropriate places to provide the expected properties, but these properties could be restored to the levels of control bread dough by the addition of sugar and yeast following the first proof, mold, and second proof steps.     

Effects of laccase and xylanase on the chemical and rheological properties of oat and wheat doughs

The effects of Trametes hirsuta laccase and Pentopan Mono BG xylanase and their combination on oat, wheat, and mixed oat-wheat doughs and the corresponding breads were investigated. Laccase treatment decreased the content of water-extractable arabinoxylan (WEAX) in oat dough due to oxidative cross-linking of feruloylated arabinoxylans. Laccase treatment also increased the proportion of water-soluble polysaccharides (WSNSP) apparently due to the beta-glucanase side activity present in the laccase preparation. As a result of the laccase treatment, the firmness of fresh oat bread was increased. Xylanase treatment doubled the content of WEAX in oat dough and slightly increased the amount of WSNSP. Increased stiffness of the dough and firmness of the fresh bread were detected, probably because of the increased WEAX content, which decreased the amount of water available for beta-glucan. The combination of laccase and xylanase produced slight hydrolysis of beta-glucan by the beta-glucanase side activity of laccase and enhanced the availability of AX for xylanase with concomitant reduction of the amount and molar mass of WSNSP. Subsequently, the volume of oat bread was increased. Laccase treatment tightened wheat dough, probably due to cross-linking of WEAX to higher molecular weight. In oat-wheat dough, laccase slightly increased the proportion of WSNSP between medium to low molecular weight and increased the specific volume of the bread. Xylanase increased the contents of WEAX and WSNSP between medium to low molecular weight in oat-wheat dough, which increased the softness of the dough, as well as the specific volume and softness of the bread. The results thus indicate that a combination of laccase and xylanase was beneficial for the textures of both oat and oat-wheat breads.     

麦麸酚基木聚糖对发酵面团特性和馒头品质的影响

为了提高麦麸的附加值、馒头的品质以及增强馒头的营养价值,该试验以小麦粉为原料,采用2个分子量的麦麸酚基木聚糖（820、581 kD）,研究不同添加量（0.25%、0.5%、1.0%、2.0%）对发酵面团特性以及馒头品质的影响。结果表明：随着麦麸酚基木聚糖添加量的增加,发酵面团的弹性模量、质子密度A22先增加后下降,黏性模量、质子密度A23增加,弛豫时间T22下降;馒头的亮度下降,红度和黄度增加,比容、黏聚性、回复性先增加后下降,硬度、咀嚼性先下降后上升,黏附性下降,馒头的感官得分先上升后下降。高分子量的麦麸酚基木聚糖,其发酵面团的弹性模量和黏性模量变幅较大,弛豫时间T22、T23较大、质子密度A21较小,低分子量的麦麸酚基木聚糖,其馒头比容和弹性较大,但馒头硬度和咀嚼性相对也较大。麦麸酚基木聚糖添加量在0.5%时,对发酵面团以及馒头品质改善效果最好。添加量在1.0%内,发酵面团特性以及馒头品质均可接受。高分子量的酚基木聚糖对发酵面团以及馒头品质改善效果高于低分子量的酚基木聚糖。研究结果为麦麸酚基木聚糖广泛应用于馒头中,提高馒头品质及营养价值提供理论依据。     

沙蒿胶对面团流变性质的影响及在面包加工中的应用

该文重点研究了添加沙蒿胶对面团流变性质以及面包品质的影响。粉质特性的结果表明,添加沙蒿胶使面团的吸水率增加,面团的形成时间和稳定时间延长、弱化度降低、拉伸性提高,面团的稳定性增强。动态流变性质表明,添加沙蒿胶后,面团的黏弹性均得到了提高。质构分析的结果表明,添加沙蒿胶使面包的醒发时间、硬度值、胶着性、咀嚼性下降,面包的比容、弹性、内聚性提高,明显地改善了面包的品质。     

Effect of Dough Processing Conditions and DATEM on Norwegian Hearth Bread Prepared from Frozen Dough

The objective of this study was to examine treatments that directly influence Norwegian lean doughs destined to be frozen. Therefore a strip-block experimental design with four dough treatment factors (wheat flour blend, diacetyl tartaric acid esters of monoglycerides [DATEM], water absorption, and dough temperature) and two storage factors (frozen storage time and thawing time) was used. Four levels were selected for frozen storage time and two levels were selected for the remaining factors. After frozen storage (2–70 days), the doughs were thawed and baked. Principal component analysis showed that to obtain a high loaf volume and bread score after freezing, a high dough temperature after mixing (27°C) was essential. The highest form ratio (height/width) level was obtained after 28 days of frozen storage and with a short thawing time (6 hr). Analysis of variance (ANOVA) of dough treatments showed that an increase in dough temperature from 20 to 27°C after mixing resulted in a significant increase in loaf volume (1,653 to 2,264 mL), form ratio (0.64 to 0.69), and bread score (1.7 to 3.2), and a reduction in loaf weight (518.4 to 512.5 g) and crumb score (7.9 to 5.9, i.e., a more open bread crumb). Also, the addition of DATEM significantly increased loaf volume (1,835 to 2,081 mL), form ratio (0.64 to 0.69), and bread score (2.2 to 2.6). Frozen dough storage time significantly affected loaf volume, loaf weight, bread score, and crumb score. Increasing thawing time from 6 to 10 hr significantly increased loaf volume (1,855 to 2,121 mL), and reduced the form ratio (0.69 to 0.63) and loaf weight (516.8 to 511.4 g). ANOVA of the interaction between dough treatment and frozen storage time showed that decreasing water absorption significantly increased the loaf volume.     

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 Glycerol and Sorbitol on the Properties of Dough and White Bread

Polyols could prolong shelf life and improve the quality of white bread. But the effect of high contents of polyols on dough properties and bread qualities is not yet clearly known. Thus, the properties of dough and white bread with different addition of polyols were evaluated by means of selected physicochemical properties. Rheology experiment results showed that both glycerol and sorbitol decreased the G′ and G″ of the dough. The results of thermogravimetric analysis revealed that polyols hindered the evaporation of water and that glycerol had a greater capacity for water retention than did sorbitol. In the bread, they caused more water to be absorbed on the surface of the gluten–starch system. They decreased the water activity and mass loss of the bread, but the specific volume of the bread also decreased. We found when glycerol and sorbitol addition was higher than 8%, it could slightly increase the viscidity of dough, enhance the moisture content of bread, and reduce the water activity of bread. But the gluten strength of dough decreased, and shaping and proofing of dough were difficult, which resulted in the deterioration the quality of white bread. We conclude that the addition of glycerol or sorbitol below 8% would be beneficial to the properties of dough and white bread and that sorbitol is a better option than glycerol.     

Effects of tyrosinase and laccase on oat proteins and quality parameters of gluten-free oat breads

Effects of a Trichoderma reesei tyrosinase (TYR) and a Trametes hirsuta laccase (LAC) on breadmaking performance of gluten-free oat flour were investigated by SDS-PAGE analysis of oat protein fractions, large deformation rheology, and microscopy of the doughs, as well as on the basis of specific volume and firmness of the gluten-free breads. TYR induced the formation of higher molecular weight proteins in the SDS-PAGE assay. Microscopical analysis showed more intensive protein aggregation in the TYR-treated dough than in the dough without TYR. TYR also increased the firmness of the dough, which was assumed to be because of the cross-linking of oat globulins. LAC did not affect the oat globulins. TYR alone, or together with a commercial Thermomyces lanuginosus xylanase (XYL), increased significantly the specific volume of the gluten-free oat bread. A combination of TYR and XYL also increased the softness of the bread, whereas a combination of LAC and XYL improved the specific volume but did not affect the softness of oat bread. The results thus indicate that cross-linking of oat globulins by TYR, especially with the addition of XYL, was beneficial for improving the texture of gluten-free oat bread.     

Effects of Bran Prehydration on Functional Characteristics and Bread‐Baking Quality of Bran and Flour Blends

The effect of bran prehydration on the composition and bread‐baking quality was determined using bran and flour of two wheat varieties. Bran was hydrated in sodium acetate buffer (50mM, pH 5.3) to 50% moisture at 25 or 55°C for 1.5 or 12 h. The soluble sugar content in bran increased with prehydration. Decreases in phytate and soluble fiber were observed in prehydrated bran, but insoluble fiber was not affected by prehydration. Likewise, free phenolic content decreased, and there was little change in the content of bound phenolics in prehydrated bran. The compositional changes were greater in the bran prehydrated at 55 than at 25°C, and for 12 than for 1.5 h. Addition of prehydrated bran delayed dough development of bran and flour blends and slightly increased water absorption of dough. A higher loaf volume of fresh bread and lower crumb firmness of bread stored for 10 days were observed in bread containing bran prehydrated at 25°C than in bread containing nonhydrated bran or bran prehydrated at 55°C. The prehydration of bran at 25°C before being incorporated into refined flour for dough mixing improved bread quality by altering bran compositional properties, allowing enough water to be absorbed by fibrous materials in the bran and preventing water competition among dough constituents.     

Effects of Ferulic Acid and Transglutaminase on Hard Wheat Flour Dough and Bread

The effects of ferulic acid and transglutaminase (TG) on the properties of wheat flour dough and bread were investigated. Ferulic acid and TG were blended with hard wheat flour at levels of 250 and 2,000 ppm of flour weight, respectively. The addition of ferulic acid reduced the mixing time and mixing tolerance. The addition of TG did not obviously affect the mixing properties. Significant effects of ferulic acid plus TG on the rested dough texture were observed for overmixed dough. The maximum resistance (Rmax) of the dough was significantly reduced with the addition of ferulic acid but increased with the addition of TG. The addition of TG with ferulic acid restored the Rmax reduced by ferulic acid alone. The proportion of SDS‐soluble high molecular weight proteins in the dough increased with the addition of ferulic acid and decreased with TG, when assessed with size‐exclusion HPLC fractionation. Although the addition of TG improved the handling properties of the dough made sticky with added ferulic acid, it did not improve the quality of the bread with added ferulic acid as measured by loaf volume and firmness.     

Pyranose Oxidase from Trametes multicolor Impacts Dough and Bread Microstructure

Pyranose oxidase (P₂O) improves wheat flour dough stability and bread quality. We related its effect on dough spread behavior to that on dough and bread crumb structure. Increasing P₂O addition levels gradually reduced dough flow. High P₂O addition levels further increased dough strength, significantly increased dough cell wall thickness, and decreased bread loaf volume. Taken together, affecting dough spread behavior impacts dough and bread (crumb) structure, and dough structure largely determines bread crumb structure.     

Effects of DATEM on Dough Rheological Characteristics and Qualities of CSB and Bread

Diacetyl tartaric acid ester of monoglycerides (DATEM) is a kind of anionic emulsifier. To date, the positive effect of DATEM on the volume of bread has been reported, but the effects on Chinese steamed bread (CSB) quality and other parameters for bread quality are still unclear. The effects of DATEM on the characteristics of dough and the qualities of CSB and bread were investigated. The results showed that, the effects of DATEM on the rheological properties of dough were complex. Water absorption ratio of CSB dough decreased slightly, while that of bread dough increased slightly. But gas retention and structure improved and gluten strength increased for both CSB and bread doughs after DATEM was added. The studies also showed that structure, elasticity, tenacity, and whiteness of CSB were improved, but specific volume was almost unchanged. The structure, color, and smoothness were significantly improved for bread, and specific volume increased compared with the control. The optimal quantities of DATEM for CSB and bread were both ≈0.10% (on flour mass basis).     

Effects of Commercial Hydrolytic Enzyme Additives on Canadian Short Process Bread Properties and Processing Characteristics

The effects of increasing levels of eight commercial enzymes representing four types of fungal hydrolytic enzymes (α‐amylases, proteases, xylanases, and cellulases) on Canadian short process (CSP) bread quality and processing characteristics were studied. Addition of all enzymes types at optimum levels resulted in increased loaf volume and bread score and softer crumb. All four types of enzymes appeared to be equally effective in improving bread properties compared with the controls. At high levels, greater tolerance to the addition of xylanases and cellulases compared with the addition of α‐amylases and proteases was apparent. Mixing requirements increased with increasing levels of α‐amylase but no change was apparent with the other enzymes. Addition of all enzymes reduced sheeting work requirements, indicating a dough softening effect. Optimum bread properties for all enzymes were attained within a relatively narrow range of dough sheeting work values, which presumably correspond to optimum dough handling properties. The similarity in response of bread and sheeting characteristics at optimum levels of addition for all four enzyme types suggests a common nonspecific mechanism for improver action that is probably related to water release and the resulting impact on physical dough properties.     

Effects of Commercial Hydrolytic Enzyme Additives on Japanese‐Style Sponge and Dough Bread Properties and Processing Characteristics

The effects of increasing levels of eight commercial fungal enzymes enriched in four types of activity (α‐amylase, protease, xylanase, or cellulase) on Japanese‐style sponge and dough bread quality and processing characteristics have been studied using a Canadian red spring wheat straight‐grade flour. At optimum levels, the enriched α‐amylases, xylanases, and cellulases increased loaf volume and bread score and reduced crumb firmness, while the proteases only reduced crumb firmness. For α‐amylases, xylanases, and cellulases, optimum levels for crumb firmness were obtained at higher levels of addition than for loaf volume and bread score. At high levels of addition, all four enriched enzyme types reduced loaf volume and bread score and increased crumb firmness relative to optimum levels, with the proteases showing the most dramatic effects. α‐Amylases and cellulases had little impact on dough mixing requirements, while xylanases increased and proteases greatly reduced mixing requirements. All enzymes at optimum levels reduced sheeting work requirements, resulting in softer more pliable dough. Optimum bread properties for α‐amylases, xylanases, and cellulases were attained within a relatively narrow range of dough sheeting work values. This similarity in response suggests a dominant common nonspecific mechanism for their improver action, which is most likely related to water release and the resulting impact on physical dough properties.     

Elucidating the mechanism of laccase and tyrosinase in wheat bread making

Cross-linking enzymes generate covalent bonds in and between food biopolymers. These enzymes are interesting tools for tailoring dough and bread structures, as the characteristics of the biopolymers significantly determine the viscoelastic and fracture properties of dough and bread. In this study, the influence of oxidative cross-linking enzymes, tyrosinase from the filamentous fungus Trichoderma reesei and laccase from the white rot fungus Trametes hirsuta, on dough and bread were examined. Oxidation of low molecular weight phenolic model compounds of flour, cross-linking of gluten proteins, dough rheology, and bread making were characterized during or after the enzymatic treatments. In the dough and bread experiments, laccase and tyrosinase were also studied in combination with xylanase. Of the model compounds tyrosine, p-coumaric acid, caffeic acid, ferulic acid, and Gly-Leu-Tyr tripeptide, tyrosinase oxidized all except ferulic acid. Laccase was able to oxidize each of the studied compounds. The phenolic acids were notably better substrates for laccase than l-tyrosine. When the ability of the enzymes to cross-link isolated gliadin and glutenin proteins was studied by the SDS-PAGE analysis, tyrosinase was found to cross-link the gliadin proteins effectively, whereas polymerization of the gliadins by laccase was observed only when a high enzyme dosage and prolonged incubation were used. Examination of large deformation rheology of dough showed that both laccase and tyrosinase made doughs harder and less extensible, and the effects increased as a function of the enzyme dosage. In bread making, interestingly, the pore size of the breads baked with tyrosinase turned out to be remarkably larger and more irregular when compared to that of the other breads. Nevertheless, both of the oxidative enzymes were found to soften the bread crumb and increase the volume of breads, and the best results were achieved in combination with xylanase.     

Fermented Sorghum as a Functional Ingredient in Composite Breads

Whole sorghum flour was fermented (a five‐day natural lactic acid fermentation) and dried under forced draught at 60°C, and evaluated for its effect on sorghum and wheat composite bread quality. In comparison with unfermented sorghum flour, fermentation decreased the flour pH from 6.2 to 3.4, decreased total starch and water‐soluble proteins, and increased enzyme‐susceptible starch, total protein, and the in vitro protein digestibility (IVPD). Fermentation and drying did not decrease the pasting temperature of sorghum flour, but slightly increased its peak and final viscosity. In comparison with composite bread dough containing unfermented sorghum flour, fermented and dried sorghum flour decreased the pH of the dough from 5.8 to 4.9, increased bread volume by ≈4%, improved crumb structure, and slightly decreased crumb firmness. IVPD of the composite bread was also improved. Mixing wet fermented sorghum flour directly with wheat flour (sourdough‐type process) further increased loaf volume and weight and reduced crumb firmness, and simplified the breadmaking process. It appears that the low pH of fermented sorghum flour inactivated amylases and increased the viscosity of sorghum flour, thus improving the gas‐holding capacity of sorghum and wheat composite dough. Fermentation of sorghum flour, particularly in a sourdough breadmaking process, appears to have considerable potential for increasing sorghum utilization in bread.     

Interactions of different carrageenan isoforms and flour components in breadmaking

The aim of this study was to compare the effects of carrageenans with different sulfate contents on bread volume and dough rheological properties. Results showed that only lambda carrageenan, the most sulfated isoform, produced a significant increase in bread volume. In contrast, the different carrageenans induced a negative effect on the cookie factor. Alveographic and farinographic analyses indicated that dough rheological properties were differentially modified depending on whether lambda carrageenan was added to flour and then hydrated or vice versa. Analysis of the interaction between lambda carrageenan and flour components by infrared spectroscopy and SDS-PAGE indicated that a pool of low molecular weight hydrophobic gluten proteins interact with carrageenan. This interaction drastically changes their physicochemical properties since carrageenan-gluten protein complexes show a hydrophilic behavior. In addition, the results indicate that carrageenan sulfate groups and probably the amino groups of glutamines present in the primary structure of gluten proteins are involved in the interaction.     

Effects of Oat Grain Hydrothermal Treatments on Wheat-Oat Flour Dough Properties and Breadbaking Quality

Hydrothermal treatments, which are routine in oat processing, have profound effects on oat flour dough rheological properties. The influence of roasting and steam treatments of oat grain on dough mixing and breadbaking properties was investigated when hydrothermally treated oat flour was blended with wheat flour. Roasting of oat grain (105°C, 2 hr) resulted in oat flours that were highly detrimental to wheat flour dough mixing properties and breadbaking quality. Steaming (105°C, 20 min) or a combination of roasting and steaming of oat grain significantly improved the breadbaking potential of the oat flours. The addition of oat flours increased water absorption and mixing requirements of the wheat flour dough and also decreased bread loaf volume. However, at the 10% substitution level, steamed oat flours exhibited only a gluten dilution effect on bread loaf volume when wheat starch was used as a reference. Oat flour in the breadbaking system decreased the retrogradation rate of bread crumb starch. The results indicate that adequate hydrothermal treatments of oat grain are necessary for oat flour breadbaking applications. Steamed oat flours used at a 10% level retarded bread staling without adversely affecting the loaf volume.     

Properties of Arabinoxylans in Frozen Dough Enriched with Wheat Fiber

The global market for frozen bread dough is rising; however, its quality could deteriorate during extended storage. Our previous study indicated that undesirable changes caused by freezing could be reduced by adding arabinoxylan‐rich fiber sources. The present study investigated the changes in arabinoxylan properties of yeasted dough during frozen storage. Dough samples made from refined, whole, and fiber‐enriched (15% either wheat aleurone or bran) flours were stored at –18°C for nine weeks, and structural properties of arabinoxylan were probed during storage. Water‐extractable arabinoxylan (WEAX) content in dough samples increased by about 19–33% during the first three weeks of storage. Prolonged storage of dough (weeks 6 and 9), however, correlated with a decline in WEAX content. Average molecular weight and intrinsic viscosity of WEAX decreased during storage for all frozen dough samples. Arabinose‐to‐xylose ratios also decreased by 11 and 6% for control and composite dough samples, respectively. There was a significant positive correlation (r = 0.89, P < 0.0001) between WEAX content of dough and bread quality throughout the storage period. The results demonstrated that changes in dough quality during frozen storage were related to changes in the content and structure of WEAX that took place during frozen storage.     

Kinetics of transglutaminase-induced cross-linking of wheat proteins in dough

The effects of TGase in dough after 15, 30, 45, and 60 min of resting time after mixing were studied with a Kieffer test. The resistance to stretching of control dough did not change greatly during the 60 min time period after mixing. In dough, TGase decreased extensibility and increased resistance to stretching and this change was already observed after the first 15 min (first measurement). The higher the enzyme dosage was, the higher the magnitude of the rheological change was. All of the doughs that contained TGase 3.8 or 5.7 nkat/g flour had a higher resistance to stretching and lower extensibility than control dough 15 min after mixing. Resistance to stretching clearly increased at a dosage of 5.7 nkat/g flour during the 15-60 min period after mixing. Extensibility increased in the control dough and in the doughs with a low enzyme dosage almost at the same rate. The evolution of air bubbles during proofing was determined with bright field microscopy and image analysis. In the presence of 5.7 nkat/g TGase, the fermented dough contained more of the smallest and less large air bubbles in comparison to the control dough. The effect of TGase and water content on the specific volume of the conventional and organic wheat bread was studied. Water did not have a significant effect on the specific volume of bread. TGase increased the specific volume of breads baked from organic flour only, when additional water (+10% of farinogram absorption) and a small enzyme dosage were used. Microstructural characterization showed that bread baked without TGase from conventional flour had a stronger protein network than that baked from organic flour. TGase improved the formation of protein network in breads baked from either normal or organic flour but at higher dosage caused uneven distribution.