Effects of cultivar and soil fertility on grain protein yield,grain protein content,flour yield and breadmaking quality of wheat

Grain protein content affects the flour yield and breadmaking characteristics of wheat (Triticum aestivum L). In this study, grain protein yield, grain protein content, flour yield and loaf volume were quantified for four wheat cultivars (Inia, Carina, Kariega and SST 86) grown under six different soil fertility regimes in a long-term fertilisation and irrigation experiment at the University of Pretoria. The experimental design was a randomised complete block replicated four times, with fertility as the main plots and cultivars as the subplot treatments. Grain protein yield, flour yield, loaf volume and mixograph dough peak mixing time varied among cultivars and soil fertility situations. Grain protein content differed among cultivars, but mixograph water absorption and dough characteristics did not differ. The highest grain protein yield was 873 kg ha⁻¹ for Carina and the lowest 527 kg ha⁻¹ for SST 86. Grain protein content averaged 131 g kg⁻¹ for Carina and 122 g kg⁻¹ for Kariega. Breadmaking performance showed that in a well-balanced soil fertility situation, Kariega produced 1025 cm³ of loaf volume while Inia averaged 950 cm³. Grain protein yield increased with increasing soil fertility, but grain protein content, flour yield, loaf volume, water absorption and mixograph peak mixing time varied with soil fertility. The interaction between cultivar and soil fertility was significant for grain protein yield, grain protein content, flour yield, loaf volume and water absorption but not dough peak mixing time. The results indicate cultivar differences in breadmaking quality characteristics and that soil fertility status affects grain protein yield, grain protein content, flour yield, loaf volume potential and water absorption but not mixograph peak mixing time and dough characteristics. © 1999 Society of Chemical Industry     

Effect of dextrans of differing molecular weights on the rheology of wheat flour doughs and the quality characteristics of pan and arabic breads

Dextrans (α-1-6-D-glucans) with weight-average molecular weights (Mw) ranging from 10 to 500 kDa were used at a rate of 20 g kg^?1 (flour basis) in order to modify doughs made from flour of the Australian hard-grained wheat cultivars Banks, Sunco and Hartog. Doughs containing dextran fractions with Mw below 100 kDa showed significant (P ± 0.01) reductions in Farinograph maximal consistency and significant increases in Farinograph development time. Additions of dextrans also resulted in significant increases in maximal resistance and significant reductions in extensibility when doughs were subjected to Extensograph testing. After addition of dextran fractions with Mw of 100 kDa or less, there were significant reductions in loaf volumes in pan bread of the cultivar Hartog manufactured by a rapid dough system and in pan bread of the cultivars Banks and Hartog made by a fermented dough system. Arabic bread supplemented with dextrans had poorer internal and keeping qualities, and reduced bread surface area, leading to significantly decreased quality scores. These observations are discussed in relation to possible interactions between neutral polysaccharides and other flour components.     

Effect of flaxseed and wheat flour blends on dough rheology and bread quality

The rheological and baking properties of flaxseed/wheat composite flours were studied. Flaxseed flour was used to replace 50, 100, 150 and 200 g kg^?1 of wheat flour in bread. Farinographic studies showed that water absorption, dough development time and mixing tolerance index increased as the amount of flaxseed flour increased, while dough stability decreased at 100, 150 and 200 g kg^?1 of flaxseed flour substitution. The extensographic energy of dough also decreased at 150 and 200 g kg^?1 flaxseed levels. The addition of increasing amounts of flaxseed flour caused a decrease in extensibility. Doughs containing 100, 150 and 200 g kg^?1 flaxseed flour showed resistance to extension comparable to that of control dough. The specific volume of flaxseed flour breads was similar to that of control bread. Crust L, a, b values of breads with flaxseed flour were lower than those of control bread. Breads with flaxseed flour gave lower crumb L and b values and higher a values than control bread. The sensory properties showed that an acceptable bread could be produced using flaxseed flour up to a level of 200 g kg^?1. Copyright © 2007 Society of Chemical Industry     

Composition of Ghanian fermented maize meal and the effect of soya fortification on sensory properties

There were no significant differences in the composition of four fermented maize doughs used by different ethnic groups in Ghana. The average maize dough contained 49.6% moisture, 37.5% starch and had a titratable acidity of 4.3 mg NaOH g^?1 and pH of 3.76. Fermented maize dough (48% m.c.) was fortified with defatted soya flour at 50, 100, 150 and 200 g kg^?1 on a replacement basis and used in two traditional food products. Triangle taste tests indicated a significant difference between the control and samples fortified with 10% or more soya flour. Based on a preference test, maize dough products with up to 10% added soya flour were acceptable to Ghanaians.     

Separation of bread wheat flours into starch and gluten fractions: effect of water temperature alone or in combination with water to flour ratio

Two different commercial bread wheat flours (BF‐I, 65% extraction and BF‐V, 86% extraction) were separated into gluten and starch milk by making a dough, allowing some time for maturation, dispersing the dough in water and wet sieving/washing. The effect of using of warm water (20–45 °C) for dough making and washing on separation was studied for BF‐I flour at 640 g kg^?1 water to flour ratio of and 300 s maturation time, and the separation was found to improve with increase in temperature. The combined effects of water temperature (20–50 °C) and water to flour ratio (640–780 g kg^?1 for BF‐I and 620–870 g kg^?1 for BF‐V) were studied at 600 s maturation time. The quantities and dry matter contents of the gluten fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailing and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content, and the fractional recoveries of dry matter and protein in the gluten fraction, prime starch, tailings and decantate were calculated. The results indicated the optimum point for BF‐I flour to be the combination of optimum farinograph water absorption and 40 °C. BF‐V showed very poor separation behaviour within the ranges studied. At the optimum farinograph water absorption the use of warm water for dough making and 20 °C water for washing steps was also tried, but no significant improvement over the 20 °C results was obtained. © 2002 Society of Chemical Industry     

Effect of semolina and absorption level on extrusion of spaghetti containing non‐traditional ingredients

Specific mechanical energy (SME), mechanical energy, extrusion rate and temperature of extruded spaghetti were monitored to determine the effects of semolina, hydration level and non‐traditional ingredients on pasta extrusion using a semi‐commercial pasta press with a fixed screw speed of 25 rpm. SME transferred to the dough during extrusion and the temperature of extruded spaghetti were greater with strong than with weak gluten semolina and at low than at high absorption levels. When compared with semolina hydrated to 300 g kg^?1 absorption, SME transferred to the dough was 13 kJ kg^?1 lower for semolina mixed with buckwheat (Fagopyrum esculentum Moench.) bran flour, 47 kJ kg^?1 lower for semolina mixed with flaxseed (Linum usitativissimum L.) flour and 7 kJ kg^?1 lower for semolina mixed with wheat (Triticum turgidum var. durum L.) bran. Weak gluten semolina, high absorption levels and non‐traditional ingredients reduced the mechanical energy required for extrusion more than they reduced extrusion rate. The target temperature for extruded spaghetti was 45 °C. The temperature of extruded spaghetti containing flaxseed flour was below 45 °C whereas the temperature of spaghetti containing wheat bran was above 45 °C, regardless of semolina type or absorption level. Copyright © 2006 Society of Chemical Industry     

Wet separation of wheat flours into starch and gluten fractions: the combined effects of water to flour ratio–dough maturation time and the effects of flour aging and ascorbic acid addition

The process of making a dough, allowing time for maturation, dispersing the dough in water and wet sieving/washing to obtain a protein fraction and starch milk was studied using response surface methodology by changing the water to flour ratio in dough making (400–710 g kg^?1), maturation time (45–660 s) and the type of flour. Two grades of bread wheat flour and durum clear flour were studied. The effects of aging at ambient temperature for up to 29 days and the addition of ascorbic acid at 100 or 500 mg kg^?1 flour on separation behaviour were also studied for freshly milled high‐grade (65% extraction) bread wheat flours at constant maturation time, 600 s, and at optimum farinograph water absorption value. The quantities and dry matter contents of the protein fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailings and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content. The fractional recoveries of dry matter and protein in the protein fraction, prime starch, tailings and decantate were calculated for each experiment. The acid values of flour oils were also determined on some aged flour samples. The results indicated superior separation characteristics in high‐grade wheat flour compared with lower‐grade flours. The water to flour ratio was more influential than maturation time within the range studied. Contrary to the initial expectation, no statistically significant effect of flour aging was observed in the studies with no additive, and ascorbic acid addition was not found to improve the wet separation behaviour, the separation behaviour becoming even worse at the 100 mg kg^?1 level. Acid value showed a slight increase with time. © 2002 Society of Chemical Industry     

The effect of the combination of reducing and oxidising agents on the viscoelastic properties of dough and sensory characteristics of buns

BACKGROUND: The effects of mixtures of reducing and oxidising agents on the rheological characteristics and quality of wheat flour dough and the sensory characteristics of buns were studied. RESULTS: In chemical analyses, no differences between control dough and doughs with individual mixtures of additives were found. Rheological measurements showed that increasing addition of L ‐ascorbic acid + L ‐tryptophan mixture to the dough increased its tenacity and decreased its extensibility. Increasing addition of L ‐ascorbic acid + L ‐threonine mixture also led to an increase in dough tenacity but to a slight increase in dough extensibility. Increasing addition of L ‐ascorbic acid + inactivated dry yeast mixture to the dough resulted in a decrease in tenacity and an increase in extensibility. Two other additive mixtures, L ‐ascorbic acid + L ‐cysteine hydrochloride monohydrate and L ‐cysteine p.a. + inactivated dry yeast, reduced both the tenacity and extensibility of the dough. In sensory analyses, differences in dryness, pliability, sensation when swallowing, quality and texture of buns with additive mixtures were found in comparison with control buns, but gumminess did not change significantly with increasing amount of additive mixtures. CONCLUSION: The additive mixtures tested had a positive influence on bakery products. Copyright © 2010 Society of Chemical Industry     

Dynamic rheology of wheat flour dough. II. Assessment of dough strength and bread‐making quality

Controlled stress rheometry revealed that differences in wheat flour dough strengths could be observed by means of dynamic rheological measurements in the region of higher stress amplitude (ie >100 Pa). At lower stress amplitude (τ_o) the values of elastic modulus G′ for weak doughs were higher than those for strong doughs, but they decreased substantially beyond 100 Pa stress amplitude (τ_o), such that the G′ values for strong doughs crossed over the G′ values for weak doughs. Beyond a critical value of stress amplitude (ie 100 Pa), true differences in dough strengths could be seen on the basis of their elastic characteristics, because at large deformations protein–protein interactions played a more dominant role in the rheological behaviour of flour doughs. Dynamic rheological analysis demonstrated a very weak inverse relationship (R² = 0.16) between the G′ values of flour doughs and loaf volume data for 12 wheat cultivars of diverse bread‐making performance. However, the G′ values of glutens showed significant positive relationships with bread‐making performance, explaining 73% of the variation in loaf volume. © 2002 Society of Chemical Industry     

A comparison of the ability of several small and large deformation rheological measurements of wheat dough to predict baking behaviour

The rheological characteristics of twenty wheat flour samples obtained from four organic flour blends and a non-organic control were compared in relation to their ability to predict subsequent loaf volume in the baked bread. The flour samples considered had protein contents that varied between 11–14 g/100 g. Four different rheological methods were employed. Oscillatory stress rheometry on the protein gel extracted from the wheat flour, oscillatory stress rheometry and creep measurement on undeveloped dough samples and biaxial extensional measurements on simple flour–water doughs. None of the fundamental rheological parameters correlated with loaf volume. There was a correlation between the storage modulus of the gel protein and storage modulus for the undeveloped dough (r = 0.85). There was a weak negative correlation between protein content and biaxial extensional viscosity (r = −0.62). Stepwise multiple regression related loaf volume to dough stability time (measured on the Farinograph) and tan (phase angle) for the undeveloped dough samples (overall model r² = 0.54). The results indicate that the four rheological tests considered could not be used as predictors of subsequent loaf volume when the bread is baked.     

Effect of Amino Acids and Peptides on Mixing and Frozen Dough Properties of Wheat Flour

Free amino acids, peptides, and vital wheat gluten were investigated to determine their effect on the mixing and frozen dough baking properties of wheat flour. Addition of 1% cysteine and aspartic acid decreased and glutamic acid, histidine, arginine, and lysine increased the mixing tolerance of flour. Cystine, methionine, tryptophan, and phenylalanine increased but isoleucine, histidine, glycine, arginine, glutamic acid, aspartic acid, and lysine decreased loaf volume of nonfrozen dough breads. However cystine, methionine, tryptophan, and phenylalanine did not increase loaf volume of bread prepared from frozen dough. Vital wheat gluten increased mixing tolerance and bread loaf volume only for the nonfrozen dough. However, wheat gluten hydrolysate, corn, and bonito peptides decreased mixing tolerance after optimum mixing time and were effective in increasing loaf volume for both frozen and nonfrozen dough. As the amount of corn and bonito peptide increased, specific loaf volumes also increased. Addition of 2.5% corn peptide was most effective in increasing loaf volume of frozen dough bread. Crust browning and crumb stickiness increased, whereas crumb softness decreased with addition of peptides. Addition of less than 1% peptide did not adversely affect the aftertaste and off‐flavor of bread. These results suggest that addition of peptides are effective for improving the baking quality of frozen dough, whereas amino acids and gluten have no effect.     

Effects of green tea extract on the quality of bread made from unfrozen and frozen dough processes

Two different green tea extracts (GTE‐A and ‐B) as a rich source of tea catechins were incorporated into a no‐time bread‐making process, where bread made from the unfrozen and frozen dough processes was compared by specific volume and texture profile. GTE‐A and ‐B both exhibited significant effects on bread volume and firmness, but to a different extent. GTE‐A with higher content of tea catechins (73%) at a level of 1.5 g kg^?1 flour was found to lead to a significant reduction in bread volume in unfrozen dough process and an increment in firmness during storage for 4 days at ambient temperature (22 °C). GTE‐B, with a lower content of catechins (60%), had relatively mild effects on the bread quality. Significantly negative effects were evident starting at a higher level of 5.0 g kg^?1 flour in unfrozen dough process. Frozen storage showed more predominant deteriorating effects than the GTEs over a period of 9 weeks frozen storage at ?20 °C. Copyright © 2006 Society of Chemical Industry     

Prediction of mechanical dough development,water absorption and baking performance from farinograph parameters

Two systems for measuring flour water absorption (WA), the farinograph (FAR) and the Wheat Research Institute, 125 g mechanical dough development (MDD) standard bake test system, were compared using a representative sample of 20 commercial flours. A highly significant correlation (r = 0.93) was found which yielded the predictive equation: WA_MDD = 0.66 × WA_FAR + 181 The 95% prediction limits for 125 g MDD water absorptions from this equation were ± 15 g kg^?1. This degree of accuracy was largely due to excellent farinograph reproducibility. Other farinograph parameters (development time, stability and breakdown) were highly correlated with the work input required for 125 g mechanical dough development, but only development time was significantly correlated with the volume of loaves baked on the 125 g standard bake system. This lack of prediction of baking quality for the farinograph could partly be because it simulates bulk fermentation mixing, rather than the more intensive mixing of the mechanical dough development process used for the loaves in this experiment. However, the loaf volume range was diminished since sample preparation involved bulking flours by water absorption.     

Rheology and baking potential of wheat/plantain composite flour

The possibilty of producing bread from wheat/plantain composite flour has been comprehensively assessed. The chemical analysis of the composite flour showed that it contained less protein and higher carbohydrate and minerals than wheat flour. With increasing levels of supplementation with plantain the water absorption capacity and dough development time of the composite flour decreased. However, the mixing tolerance time increased and the mixing quality decreased. It was found that the baking quality decreased with increasing level of supplementation and when unblanched plantain flour was used. The blend with 100 g kg^?1 blanched plantain and 900 g kg^?1 wheat flour was found to be internally and externally better than other blends and the bread was of acceptable quality.     

Effect of phenolic acids on the rheological properties and proteins of hard wheat flour dough and bread

BACKGROUND: The effects of different phenolic acids on the rheological properties and gluten proteins of hard wheat flour dough and bread were investigated. Caffeic, ferulic, syringic and gallic acids were each blended with hard wheat flour at a concentration of 4.44 µmol L^?1 g^?1 flour. RESULTS: Mixing time and tolerance were reduced with the addition of phenolic acids. The phenolic acids reduced the maximum resistance to extension (R_max) and increased the extensibility of dough, with effects in the following order: gallic < syringic < ferulic < caffeic acid. The effect on R_max was more pronounced in overmixed dough. Loaf volume was most significantly decreased with the addition of caffeic acid. Extraction of sodium dodecyl sulfate‐soluble high‐molecular‐weight proteins was increased in both mixed and fermented doughs by the addition of ferulic and caffeic acids. The order of influence of the phenolic acids on the rheological properties and protein structure of dough and bread was consistent with that of their antioxidant activity. CONCLUSION: The addition of caffeic and ferulic acids reduced R_max and increased the extensibility of hard wheat flour dough by modifying the high‐molecular‐weight gluten, which resulted in decreased bread volume. Copyright © 2011 Society of Chemical Industry     

Effects of two barley β-glucan isolates on wheat flour dough and bread properties

The effects of wheat flour fortification with two different molecular weight barley β-glucan isolates (1.00 × 10⁵, BG-100 and 2.03 × 10⁵, BG-200) on the rheological properties of dough and bread characteristics, using flours from two wheat cultivars that differ in their breadmaking quality, have been examined. The farinograph water absorption of doughs and the moisture content and water activity of the breads increased with increasing β-glucan content; the β-glucan isolate with the higher molecular weight (BG-200) exerted a greater effect than did BG-100. The addition of β-glucans to the dough formula increased the development time, the stability, the resistance to deformation and the extensibility of the poor breadmaking quality doughs, as well as the specific volumes of the respective breads, exceeding even that of the good breadmaking cultivar. Furthermore, the colour of the bread crumbs got darker and their structure became coarser, whereas the bread crumb firmness decreased with increasing level of β-glucan addition. Generally, the BG-200 was more effective in increasing the specific bread volume and reducing the crumb firmness, especially when used to fortify the poor breadmaking quality flour. The results further indicate a requirement for optimisation of the fortified doughs (level and molecular size of the β-glucan) to maximise bread quality attributes (loaf volume, texture, and staling events).     

Rheological and baking properties of cowpea and wheat flour blends

Effect of blending 50 to 250 g kg⁻¹ cowpea flour in wheat flour on rheological, baking and sensory characteristics of bread, chapati, cookies and muffins was studied. Farinograph water absorption, dough development time, mixing tolerance index and dough stability increased significantly with increased amount of cowpea flour. Incorporation of cowpea flour lowered gelatinisation time and peak viscosity. Loaf volume and overall acceptability scores of bread were reduced significantly beyond 150 g kg⁻¹ incorporation of cowpea flour. There were significant changes in specific volume and overall acceptability scores of muffins, registering an initial improvement up to 50 g kg⁻¹ and a significant decline thereafter. © 1999 Society of Chemical Industry     

Quality of bread made from ozonated wheat (Triticum aestivum L.) flour

BACKGROUND: Ozone gas could be used as a fumigant during grain and flour storage. Experiments were conducted to determine the effects of exposure to ozone and the effects of blending ozone‐treated flour with control flour on flour functionality and bread‐making quality. RESULTS: Ozone treatment oxidized lipids, increased brightness and reduced the yellow hue of flour, and increased peak viscosity and setback viscosity of flour. Bread made from flour treated with ozone at 1500 mg kg^?1 for 4.5 min and bread made from flour blended with 100 g kg^?1 ozonated flour had good crust color and a whiter crumb and had more crumb cells, which resulted in a greater specific volume of the bread when compared with control flour. Flour functionality declined as ozone exposure increased beyond 9 min and as the concentration of ozonated flour increased beyond 200 g kg^?1. CONCLUSION: Bread made from flour exposed to ozone for 4.5 min or flour that contained 100 g kg^?1 fully ozonated flour had greater specific loaf volume and whiter crumb compared to bread made with control flour. Exposure of flour to ozone for longer times (9–45 min) and higher blends (200–1000 g kg^?1) deteriorated quality of bread. Copyright © 2011 Society of Chemical Industry     

Flour,starch and composite breadmaking quality of various cassava clones

Bread was made using a straight-dough baking process from a local soft wheat flour partially substituted at four levels with flour from nine different cassava (Manihot esculenta, Crantz) clones. The physicochemical properties of the blended flouts, including starch quality, were determined and related to dough rheology, bread volume and crumb characteristics. Breadmaking quality at substitution levels of 100 and 200 g kg^?1 of mixed flour was reliably predicted from the cassava flour diastatic activity only. Flours with relatively high diastatic activities, ie above ～ 145 mg of maltose, had deleterious breadmaking effects. Baking absorption effects were more critical at substitution levels of 300 and 400 g kg^?1. Cassava flour diastatic activity was highly dependent on the moisture contents of the respective tuberous roots, and affected the extent of starch gelatinisation in the breadcrumbs.     

Effect of β-Glucan Concentrate on the Water Uptake,Rheological and Textural Properties of Wheat Flour Dough

The effects of the addition of β-glucan concentrate (2.5–10 g/100 g flour) and water (58–70 mL/100 g flour) on the rheological and textural properties of wheat flour doughs were studied. Various empirical (farinograph, extensograph, dough inflation, and dough stickiness) and fundamental rheological tests (oscillatory and creep-recovery) were employed to investigate composite dough structure and an attempt was made to correlate the data obtained from different instrumental measurements. The water absorption increased with the addition of β-glucan concentrate into wheat flour. An increase in mixing time and stability were recorded upon addition of β-glucan concentrate (≤ 5 g/100 g flour), and the extensibility decreased at similar condition. The composite dough exhibited predominating solid-like behavior. The mechanical strength, dough stickiness, the peak dough inflation pressure decreased with increasing water content but those parameters increased with β-glucan concentrate incorporation within the studied concentration range. Creep-recovery tests for 5 g β-glucan concentrate/100 g flour doughs recorded less resistance to deformation with an increase in water level and data were well described by the Burger model. Thermal scanning of doughs revealed that the protein denaturation peak was significantly influenced by water content, and the values were ranged between 110 and 124°C. Significant relationships between empirical and fundamental rheological testing methods were found.