Determining Wheat Dough Mixing Characteristics from Power Consumption Profile of a Conventional Mixer

A Hobart mixer with a pin‐type attachment was used to mix soft wheat flour dough. Power consumption profiles were measured continuously during mixing for 20 min using a current transducer and a data logging system. Experimental variables were quantity of flour (500, 1,000, and 1,500 g of dry wheat flour), water content (43, 45, and 47%, wb), and mixer speed setting (low, medium, and high). The power consumption profiles were evaluated by moving average and spectral analysis. Peaks in the power consumption profiles were located to determine the optimal mixing time. The optimal mixing times were then compared with storage and viscous moduli measured using a dynamic rheometer to assure the maximum strength of wheat dough at the optimal mixing time. Tolerance was determined using the signal amplitude and phase angle data from spectral analysis. Optimal mixing times of various doughs at medium speed ranged from 510 to 850 sec; low and high flour quantities required longer mixing times than medium quantity of flour. The optimal mixing time increased when the moisture content was lowered. Tolerance was affected by mixing speed and moisture content of flour     

Starch Pasting and Textural Attributes of Elbow Macaroni as Impacted by Dough Moisture,Dough Mixing Time,and Macaroni Cooking Time

The effects of dough moisture, mixing time, and cooking time on uncooked and cooked elbow macaroni by means of starch pasting and macaroni textural characteristics were investigated. In conventional elbow macaroni production, cooking time was found to have significant contributions to cooked macaroni starch pasting properties, indicating that degree of starch cook dependent on cooking time was the main influence on cooked macaroni starch pasting phenomena. Dough moisture also showed some significant (P < 0.05) relationships with cooked macaroni starch pasting properties; however, mixing time did not show significant effect. Cooked macaroni starch pasting properties showed significantly (P < 0.05) high correlations with cooked macaroni firmness and stickiness. Cooking time was the only major variable contributing to variations in cooked elbow macaroni starch and consequently in pasting and texture characteristics. Cooking time was highly related to firmness and stickiness of cooked elbow macaroni (P < 0.0001, R² = 0.8148; P < 0.0001, R² = 0.6215, respectively). In addition, dough moisture had a slight significant (P < 0.05) effect on cooked elbow macaroni firmness and stickiness. Cooked elbow macaroni firmness and stickiness were found to be highly correlated (P = 0.0001, R² = 0.8459). Increases in firmness increased cooked elbow macaroni stickiness. As a result, when elbow macaroni was cooked for shorter times, firmer and stickier macaroni was obtained.     

Effect of Exogenous Lipase on Dough Lipids During Mixing of Wheat Flours

In control dough, endogenous wheat lipase was inactive, because the triacylglycerol (TAG), 1,2-diacylglycerol (DAG_1,2), and 1,3-diacylglycerol (DAG_1,3) fractions of nonpolar lipids were not affected by mixing. Conversely, the free fatty acid (FFA) and monoacylglycerol (MAG) fractions decreased, mainly due to the oxidation of polyunsaturated fatty acids (PUFA) catalyzed by wheat lipoxygenase. Addition of exogenous lipase to flour (15 lipase units [LU] per gram of dry matter) resulted in substantial modification of nonpolar lipids during dough mixing. Due to the 1,3 specificity of the lipase used in this experiment, the TAG and DAG_1,3 fractions decreased, whereas the MAG and FFA fractions increased. The DAG_1,2 fraction increased at the beginning of mixing and decreased after 40 min of mixing. Moreover, part of the PUFA released by lipase activity was oxidized by wheat lipoxygenase, resulting in major losses of PUFA. Conversely, the net content of the saturated and monounsaturated fatty acids (SMUFA) remained constant, because the free SMUFA content increased primarily at the expense of the esterified forms. For a constant mixing time of 20 min, increasing the amount of lipase added to dough (from 2.5 to 25 LU/g of dry matter) resulted in a linear decrease in the TAG fraction and a linear increase in the SMUFA content in the FFA fraction. At the same time, the PUFA content of the FFA fraction increased only for additions of lipase to flour of >5 LU/g of dry matter, due to partial oxidation by wheat lipoxygenase.     

Effect of Foliar Sulfur and Nitrogen Fertilization on Wheat Storage Protein Composition and Dough Mixing Properties

Nitrogen (N) and sulfur (S) supplies have a strong influence on the quality and quantity of wheat storage proteins, which play an important role in the breadmaking process. Nitrogen derived from urea, S from micronized elemental sulfur, and a mixture of both (N+S) were applied at anthesis stage on wheat by foliar spray. To relate N and S incorporation in storage proteins to the quality of dough, their incorporation into each storage protein fraction was measured: monomers, low molecular weight glutenin subunits (LMW‐GS), and high molecular weight glutenin subunits (HMW‐GS). Then protein fraction quantities, molecular weight distribution (MWD), polymerization index (PI), and molecular dimensions of unextractable polymeric protein (UPP), as well as dough mixing properties were determined. Fertilizers N and S were differentially incorporated into each storage protein fraction, influencing protein synthesis. Moreover, after the N+S fertilization, the increase of the polymeric proteins induced an increase in molecular weight and compactness, as well as in dough strength and consistency. These results provide evidence that N and S fertilizers applied by foliar spray route at anthesis, simultaneously, play an important role in controlling the storage protein synthesis and the degree of polymerization, which in turn influence dough mixing properties.     

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.     

Effects of Transglutaminase on Rheology,Microstructure, and Baking Properties of Frozen Dough

The improving effects of transglutaminase (TGase) were investigated on the frozen dough system and its breadmaking quality. Rheological properties and microstructure of fresh and frozen doughs were measured using a Rapid Visco‐Analyser (RVA), dynamic rheometer, and scanning electron microscopy (SEM). The frozen doughs with three storage periods (1, 3, and 5 weeks at –18°C) were studied at three levels (0.5, 1.0, and 1.5%) of TGase. As the amount of TGase increased, hot pasting peak viscosity and final viscosity from the RVA decreased, but breakdown value increased. The TGase content showed a positive correlation with both storage modulus G′ (elastic modulus) and the loss modulus G″ (viscous modulus): G′ was higher than G″ at any given frequency. The SEM micrographs showed that TGase strengthened the gluten network of fresh, unfrozen dough. After five weeks of frozen storage at –18°C, the gluten structure in the control dough appeared less continuous, more disrupted, and separated from the starch granules, while the dough containing 0.5% TGase showed less fractured gluten network. Addition of TGase increased specific volume of bread significantly (P < 0.05) with softer bread texture. Even after the five weeks of frozen storage, bread volume from dough with 1.5% TGase was similar to that of the fresh control bread (P < 0.05). The improving effects of TGase on frozen dough were likely the result of the ability of TGase to polymerize proteins to stabilize the gluten structure embedded by starch granules in frozen doughs.     

Effects of Mixing Conditions on Pasta Dough Development and Biochemical Changes

Mixing of commercial durum wheat semolina with water was performed under different conditions in a Brabender micromixer equipped with pastamaking shafts. Semolina filling of the mixing chamber was 30.4–42.9% (v/v), shaft speed was 10–110 rpm, temperature was 10–40°C, and hydration level was 47–52.5% (db). The blend of water and semolina evolved from individualized hydrated particles (HP) to a dough product (DP) as a function of these conditions. Torque values (T) and the specific mechanical energies (SME) were recorded during mixing as a function of time. Terms from these curves were defined to characterize the mixing process: t_o (starting time of dough development), t_d (time to reach the maximum dough consistency), T_m (mean torque value after dough development), and SME_f (total energy applied to the dough during mixing). Transformation of HP into DP and the mixing temperature were the main parameters affecting t_o, t_d, T_m, and SME_f. Protein aggregate distribution was measured by size-exclusion HPLC, protein solubility in 0.01N acetic acid, free -SH content, soluble arabinoxylans, reducing sugars, ferulic acid, carotenoid content, and oxidase activities to characterize the biochemical changes that occurred during pasta dough formation. DP was characterized by lower amounts of insoluble glutenin aggregates, lower protein solubility in dilute acetic acid, lower free -SH content, ferulic acid, carotenoid content, and lower oxidoreductase activities as compared to HP. Once the dough was developed, the effects of mixing speed, temperature, or hydration level on the biochemical composition of the blend were null or low compared to the modifications that were observed when the blends changed from HP to DP. The t_o and SME_f were the most significant parameters in characterizing the pasta dough mixing process in relation to biochemical changes.     

Influence of Sodium Caseinate and Whey Protein on Baking Properties and Rheology of Frozen Dough

Dairy ingredients are added to bakery products to increase nutritional and functional properties. Sodium caseinate (SC) and whey protein concentrate (WPC) were incorporated into frozen dough. WPC was subjected to heat treatment (WPCHT) to eliminate undesirable weakening of the gluten network. 2% SC or 4% SC decreased proof time, increased loaf volume, and improved texture. Effects of adding 4% SC on baking quality were similar to adding ascorbic acid (AA) and diacetyl tartaric acid esters of monoglycerides (DATEM). WPC increased proof time, decreased volume, and negatively affected texture. Heat treatment of WPC improved baking performance. Bread with WPCHT had volume similar to that of the control without dairy ingredients. Adding 4% SC decreased resistance to extension (R_5cm measured with the extensigraph), while adding 4% WPC increased extensibility. Dynamic oscillation testing determined the effects of the ingredients on fundamental rheological properties. WPC decreased storage modulus (G′) and loss modulus (G″), while heat treatment of WPC increased G′ and G″. Confocal laser scanning microscopy (CLSM) showed that milk proteins affect frozen dough ultrastructure. Frozen doughs with SC had an enhanced gluten network compared with the control, while untreated WPC appeared to interfere with the gluten network.     

Protein Allelic Composition,Dough Rheology,and Baking Characteristics of Flour Mill Streams from Wheat Cultivars with Known and Varied Baking Qualities

Flour mill streams obtained by milling grain of 10 bread wheat cultivars grown in the Skopje region of Macedonia were analyzed for rheological and breadmaking quality characteristics and for composition of gliadins and HMW‐GS. The objective of this study was to examine the relationships between the composition of gluten proteins and breadmaking quality, as well as to determine the importance of gluten proteins for technological quality of flour mill streams. The grain was milled in an experimental mill according to a standardized milling procedure, with three break and three reduction passages. The addition of two vibratory finishers in the milling scheme enabled better separation of bran. A small‐scale baking method for evaluation of the breadmaking properties was developed, and electrophoretic methods including acid‐PAGE and SDS‐PAGE were used to determine the composition of the gluten proteins. There were significant differences in the degree of dough softening of individual and total flour fractions of the flour mill streams for cultivars with different alleles from six loci, for farinograph water absorption from seven loci, and for bread loaf volume and crumb quality score from six loci. The Glu‐1 quality scores for the wheat cultivars investigated were 3–9 and proved to be a useful indicator of breadmaking quality. The novel feature of the investigation related to the breadmaking potential of the flour mill streams compared with straight‐run flours.     

Environmental Influences on Flour Composition,Dough Rheology,and Baking Quality of Spring Wheat

The highly variable environmental conditions across the Pacific Northwest (PNW) influence the milling and baking quality of wheat grain produced in this region. This study was conducted to compare the flour composition, dough rheology, and baking quality of soft and hard spring wheat grain produced in diverse environments. Thirteen soft and five hard spring wheat cultivars were grown at Lind, WA (semiarid) and Fairfield, WA (high precipitation) for three years. Grain was evaluated for flour composition, rheology, and experimental baked product quality. Flour composition, rheological properties, and baking qualities were primarily influenced by the environment. Protein contents, microSDS values, and water absorption levels were significantly (P < 0.0001) higher for all cultivars grown at Lind compared with those from Fairfield. Cookie diameters were larger (P < 0.0001) for soft flours from Fairfield, whereas loaf volumes were higher (P < 0.0001) for hard wheat flours from Lind. Results indicate that producing soft or hard wheat outside of its optimal climatic zone reduces experimental baked product quality.     

Ultrasonic Investigation of the Effect of Mixing Under Reduced Pressure on the Mechanical Properties of Bread Dough

Mixing is critical to attainment of a desirable gas cell distribution in dough. By varying mixer headspace pressure, changes in the mechanical properties of dough were investigated as a function of the dough's void concentration using low frequency (50 kHz) ultrasonic techniques. For the mixer used, this allowed the volume fraction of voids (Φ) to be varied from ≈0.01 to 0.08. The ultrasonic attenuation of longitudinal waves increased linearly with increases in Φ. If, as reported, pressure reductions during mixing decrease the number density of the voids but do not affect void size, the change in attenuation is proportional to the number of voids. By contrast, the velocity of longitudinal ultrasonic waves decreased dramatically with increasing Φ in the range 0.012 < Φ < 0.03, dropping from a value near that of water to values well below the velocity of sound in air. At higher Φ, the velocity decrease was less rapid. The longitudinal elastic modulus determined from these ultrasonic results shows that the mechanical properties of the dough are sensitive to the presence of gas bubbles. At low void fractions, the elastic behavior of dough is also influenced by changes in dough matrix properties.     

Influence of Vacuum Mixing on Structural Characteristics and Physical Properties of Noodle Dough

The effects of vacuum mixing on the structural characteristics and physical properties of noodle dough were investigated using three leading Chinese wheat cultivars. Texture profile analysis showed that vacuum mixed doughs when sheeted all gave significantly higher levels of adhesiveness, elasticity, and chewiness than doughs from nonvacuum mixing. The cross section of sheeted dough mixed at 0.06 MPa had a more continuous and compact microstructure with fewer holes and gaps, as well as more even protein distribution at the surface, as evidenced by scanning electron microscopy and Fourier transform infrared microimaging. However, a higher degree of vacuum was detrimental to the developed network for weak dough. Dough mixed at 0.06 MPa had higher glutenin macropolymer content and lower free thiol group concentration compared with nonvacuum mixed doughs, which may largely relate to the improvement of dough texture. The development of the gluten network for weak gluten flour was more sensitive to the degree of vacuum.     

Association of Glutenin Subunit Composition and Dough Rheological Characteristics with Cookie Baking Properties of Soft Wheat Cultivars

The effect of flour type and dough rheology on cookie development during baking was investigated using seven different soft winter wheat cultivars. Electrophoresis was used to determine the hydrolyzing effects of a commercial protease enzyme on gluten protein and to evaluate the relationships between protein composition and baking characteristics. The SDS‐PAGE technique differentiated flour cultivars based on the glutenin subunits pattern. Electrophoresis result showed that the protease degraded the glutenin subunits of flour gluten. Extensional viscosities of cookie dough at all three crosshead speeds were able to discriminate flour cultivar and correlated strongly and negatively to baking performance (P < 0.0001). The cookie doughs exhibited extensional strain hardening behavior and those values significantly correlated to baking characteristics. Of all rheological measurements calculated, dough consistency index exhibited the strongest correlation coefficient with baking parameters. The degradation effects of the protease enzyme resulted in more pronounced improvements on baking characteristics compared with dough rheological properties. Stepwise multiple regression showed that the dough consistency index, the presence or absence of the fourth (44 kDa) subunit in LMW‐GS and the fifth subunit (71 kDa) subunit in HMW‐GS were predominant parameters in predicting cookie baking properties.     

Effects of Cumin and Ginger as Antioxidants on Dough Mixing Properties and Cookie Quality

The effects of cumin and ginger as antioxidants on dough mixing properties and cookie quality were evaluated. Antioxidant activities in cookies were estimated by total phenolic compounds (TPC) contents and free radical scavenging activities. The cookie dough development was evaluated using Mixolab equipment which showed that addition of cumin did not change dough stability and C2, but decreased C3 and C4. While the addition of 5% ginger decreased dough stability (from 8.4 in the control sample to 6.7 min with 5% ginger addition), C2 (from 0.49 in the control sample to 0.31 N·m with 5% ginger addition), C3, and C4. Cookies formulated with addition of cumin and ginger had increased spread ratios, were softer, and had lower L* and b* values (were darker) than the control. Sensory analysis showed that cookies with cumin and ginger additions had overall acceptability similar to that of the the control with a slightly darker appearance, as confirmed by color determination. Using cumin and ginger significantly increased TPC contents from 78.5 in the control to 93.0 and 109.8 mg of gallic acid equivalent/100 g, respectively. Similar results were observed in the antioxidant activity measured by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), which increased from 41.0% in the control to 51.5% and 64.6%, respectively, for cookies with 5% addition of cumin and ginger.     

Effect of Storage Temperature and Flour Water Content on Lipids,Lipoxygenase Activity,and Oxygen Uptake During Dough Mixing

Flours differing in water content of 10% (F10), 12% (F12), and 14% (F14) were stored for 16 weeks at 22, 32, and 45°C. The major changes in lipids concerned the free fatty acids (increase) and the triglycerides (decrease). In all cases, the changes increased with increasing storage temperature and water content. After 16 weeks of storage, the losses in lipoxygenase (LOX) activity increased with increasing flour moisture and storage temperature from 10% for F10 at 22°C to 100% for F14 at 45°C. At the end of storage at 22 and 32°C, the bread volumes decreased by 10 and 25%, respectively, with no statistical differences (P < 0.05) between the samples. At 45°C, the volume losses were equal to 35, 46, and 61% for the F10, F12, and F14 samples, respectively. In the same time, the flour oxidative ability (oxygen uptake during dough mixing) increased for the F10 and F12 samples with increasing storage temperature, whereas it decreased for the F14 samples stored at 45°C. Therefore, provided the residual LOX activity is sufficient (omission of the F14 samples stored at 45°C), the flour oxidative ability increased during storage and is positively correlated to its oxidable PUFA content.     

Measurement of Dynamic Dough Density and Effect of Surfactants and Flour Type on Aeration During Mixing and Gas Retention During Proofing

A new method for measuring dough densities is presented, based on weighing small dough samples in air and immersed in xylene. The method can be used to evaluate the air content of low‐density doughs and to follow the changing density of a proofing dough sample. The method is applied to evaluate the effect of flour strength and surfactant addition on dough aeration and subsequent proofing. Doughs were mixed in a high‐speed mixer from two flours, a strong breadmaking flour and a weak flour. Surfactants sodium stearoyl lactylate (SSL) and diacetyl tartrate esters of monoglyceride (DATEM) were added at three levels, and the air content, proofing dynamics, and baked loaf quality were evaluated. The air content of dough was proportional to headspace pressure in the mixer, while the strong flour occluded less air than the weak flour. Surfactants greatly improved the volume of baked loaves but appeared to have no significant effect on air incorporation during mixing. The addition of surfactants appeared to increase the rate of growth of the dough piece during proofing, possibly due to increased bubble breakup during mixing or to increased rates of mass transfer of CO₂ into bubbles during proofing.     

Effect of Adding Exogenous Oxidative Enzymes on the Activity of Three Endogenous Oxidoreductases During Mixing of Wheat Flour Dough

The behavior of different exogenous enzymes (soybean lipoxygenase [SLOX], horseradish peroxidase [HPOD], catalase from bovine liver [BCAT], and glucose oxidase [GOX] from Aspergillus niger) added to dough was studied during mixing. The effect of adding these exogenous oxidoreductases on the activity of three oxidative enzymes present in wheat flour (lipoxygenase [WLOX], peroxidase [WPOD], and catalase [WCAT]) was examined. Proper assay conditions were established to differentiate between added WLOX, WPOD, and WCAT and the corresponding activities present in wheat flour. For doughs with added SLOX, an immediate loss of extractable SLOX (≈40%) was observed which remained constant during further mixing. When compared with the control dough, addition of SLOX decreased the losses in WLOX and WCAT activities, whereas WPOD activity was unaffected. With doughs supplemented by HPOD, an immediate loss of 20% in the HPOD activity was observed which did not change after 20 min of mixing. Compared with control dough, addition of HPOD did not affect the behavior of WLOX and WPOD, whereas a slight decrease in the WCAT losses was observed. Addition of BCAT to the dough did not change the behavior of WLOX and WPOD, whereas the losses in WCAT were less rapid. Half of the extractable activity of BCAT was lost at the beginning of mixing with no change during further mixing. For doughs supplemented with GOX, 25% of the GOX activity was lost in the first 5 min of mixing and an additional loss of 20% was observed after 20 min of mixing. Compared with dough without GOX, addition of GOX decreased the losses in WLOX, whereas losses in WCAT and WPOD increased. Glucose and ferulic acid were also added to doughs supplemented with GOX. Added glucose decreased the losses in GOX and WLOX and did not change the behavior of WPOD and WCAT during mixing. Addition of ferulic acid promoted a slight increase of the losses in WLOX and WCAT and almost no change for GOX and WPOD.     

Competition for Oxygen Among Oxidative Systems During Bread Dough Mixing: Consequences of Addition of Glucose Oxidase and Lipoxygenase on Yeasted Dough Rheology

The effect on O₂ uptake during the mixing of yeasted dough, either unsupplemented or supplemented with glucose oxidase (GOX), horsebean flour (HB), soybean flour (SB), or combinations thereof, was studied using an airtight mixer. Two wheat flours with a low (flour A) and a high (flour B) content of free polyunsaturated fatty acids were used. Addition of HB or SB provokes a similar increase of O₂ uptake for both wheat flours, whereas addition of GOX causes a larger increase for flour A than for flour B. When the wheat flours were supplemented with HB or SB, addition of GOX caused a small but significant increase of O₂ uptake for flour A. This increase was not observed for flour B. The mixing tolerance of dough A, determined with the Chopin Consistograph, is increased by GOX addition. However, this effect is less pronounced when flour A is supplemented with HB or SB. Similarly, the relaxation index of dough B is decreased by GOX addition, but the decrease is less distinct in the presence of HB or SB. These results can be explained by a competition among yeast, GOX, and lipoxygenases (present in wheat, HB, and SB flours) for the O₂ uptake by dough, which likely decreases the amount of hydrogen peroxide produced by GOX during dough mixing. This competition for O₂ consequently also modifies the rheological properties of dough.