Evaluation of pumpkin seed products for bread fortification

Pumpkin seed products (raw, roasted, autoclaved,germinated, fermented, pumpkin protein concentrate and pumpkin proteinisolate) were incorporated into wheat flour to produce blends with proteinlevels of 15, 17, 19 and 21%. Dough properties were evaluated by afarinograph; loaves of breads were evaluated by a taste panel for crustcolor, crumb color, crumb texture, flavor, and overall quality. Resultsindicated that pumpkin seed products can be added to wheat flour up toa 17% protein level for raw, roasted and autoclaved pumpkin meal, 19%level for germinated, fermented and pumpkin protein concentrate and21% level for pumpkin protein isolate without a detrimental effecton dough or loaf quality. On the other hand, the addition of pumpkin seedproteins resulted in increasing protein, lysine and mineral contentscompared to the control. While lysine and tryptophan were the first andsecond limiting amino acids in the control bread, tryptophan and lysinewere the first and second limiting amino acids for raw, roasted, autoclaved,germinated and fermented pumpkin meal; valine and lysine and valine andtotal sulfur amino acids were the first and second limiting amino acids forpumpkin protein concentrate and isolate, respectively. In vitro protein digestibility improved when the pumpkin seed proteinswere added.     

Nutritive value of soybean,rapeseed and wheat proteins,and various blends of these vegetable proteins and their fractions in rats

Blends of vegetable proteins were prepared to improve the nutritive value of these proteins. Soybean flour, rapeseed protein concentrate, whole wheat flour, soybean 2S+11S extract, wheat albumin-globulin + glutenin (AG+G) functions, and some of their blends were compared to casein for protein efficiency ratio (PER) and apparent digestibility coefficient (ADC). Autoclaving (1 h) soybean proteins was also studied. Casein and rapeseed protein concentrate gave the highest weight gains and PER. Other protein sources gave lower values for both PER (P<0.05) and weight gain. The digestibility of all vegetable proteins was lower (P<0.05) than that of casein. PER of soybean 2S+11S extract was significantly lower (P<0.05) than that of soybean flour. Autoclaving significantly (P<0.05) improved the PER of both soybean flour and 2S+11S extract. The ADC of autoclaved 2S+11S extract was similar (P<0.05) to that of autoclaved soybean flour and significantly higher (P<0.05) than that of 2S+11S extract. Soybean flour had the lowest (P<0.05) ADC. Heat treatment destroyed antinutritional factors, probably trypsin inhibitors and/or haemagglutinins of soybean. This was accompanied by improvement in the nutritional value of protein. The four blends were chosen on the basis of amino acid composition, chromatography of proteolyzates and nutritive value of each fraction. The PER of wheat albumin-globulin and glutenin (AG+G) blend was similar (P<0.05) to that of wheat flour and lower (P<0.05) than that of all other blends used. Wheat AG+G+rapeseed protein concentrate and wheat AG+G+soybean flour blends gave the highest (P<0.05) PER. Wheat AG+G improved the PER of 2S+11S extract and of soybean flour but decreased the PER of rapeseed protein concentrate. Wheat AG+G and wheat AG+G+rapeseed protein concentrate blends gave an ADC significantly higher (P<0.05) than that of wheat AG+G blend containing soybean flour of 2S+11S extract. However, blending wheat AG+G with either 2S+11S extract of soybean flour improved ADC.     

Studies on green gram (Phaseolus aureus) protein concentrate and flour

Protein isolate from green gram (Phaseolus aureus) was prepared and the chemical composition was determined. It contained 64.04% protein, 1.8% total lipids, 27.64% total carbohydrates, 1.68% crude fibre and 4.84% ash. Iron, calcium, magnesium, copper, zinc, potassium and sodium were determined. The limiting amino acid in the protein isolate was lysine. In vitro digestibility pepsin followed the pancretion was the highest and the lowest was the digestion by pepsin alone. Water absorption, oil absorption, emulsion capacity and nitrogen solubility index (NSI) of the protein isolate were 2.26g/g, 1.24g/g, 31.4g/g and 6.8g/g, respectively. For comparison the same functional properties were determined for the flour of green gram. Replacing 5 and 10% of the wheat flour with green gram flour improved the mixing properties of dough and produced good acceptable bread. However, the addition of 15% green gram flour weakened the dough and lowered the quality of bread. Replacing 2.5, 5 and 7.5% of wheat flour with protein concentrate also weakened the mixing properties of the wheat dough and decreased the bread quality.     

Quality characteristics of northern-style Chinese steamed bread prepared from soft red winter wheat flours with waxy wheat flour substitution

Quality characteristics of northern-style Chinese steamed bread (CSB) prepared from two soft red winter (SRW) wheat flours blended with 0–30% waxy wheat flour (WWF) were analyzed to estimate the influence of starch amylose content. The increased proportion of WWF in blends raised mixograph absorption with insignificant changes in protein content and dough strength-related parameters. WWF incorporation generally increased specific volume and crumb softness of CSB. The analysis of covariance revealed that CSB quality attributes were little affected by protein content and dough strength-related parameters, indicating that starch amylose content was largely responsible for the changes in CSB quality. Flour blends with 5–10% WWF, of which starch amylose content was 22.4–24.7%, produced CSB with superior crumb structure compared to other blends, but insignificant changes in surface smoothness, stress relaxation and total score compared to the respective control wheat flours. Flour blends with 15% WWF to produce a starch amylose content of 21.4–22.7% exhibited reduced staling of CSB with total scores comparable to the respective control wheat flours. CSB prepared from blends with more than 10% WWF exhibited a higher soluble starch content, indicative of reduced starch retrogradation, than that prepared from wheat flours without WWF during storage for 3 days.     

Dough rheology and bread quality of wheat-chickpea flour blends

In this study, partial substitution of wheat flour with chickpea flour at the levels of 10, 20 and 30% was carried out to study their rheological and baking performance. Chickpea flour addition increased the water absorption and dough development time (p < 0.05), while, the extensibility of dough and the resistance to deformation were reduced. Regarding dough stability, it appears that 10% chickpea exhibited higher stability and resistance to mechanical mixing values than the control, while it decreased as the substitute level increases from 20% to 30%. The dough surface of the wheat dough and the blend with 10% was classified as “normal”, however the blend with 20% and 30% produced “sticky” dough surface. The presence of chickpea flour in dough affected bread quality in terms of volume, internal structure and texture. The color of crust and crumb got progressively darker as the level of chickpea flour substitution increased. While the substitution of wheat flour with 10% chickpea flour gave loaves as similar as control.     

The comparison of the effect of added amaranth,buckwheat, chickpea,corn, millet and quinoa flour on rice dough rheological characteristics,textural and sensory quality of bread

Gluten free (GF) flour (amaranth, buckwheat, chickpea, corn, millet and quinoa) was blended with rice flour to compare their impact on dough rheological characteristics and bread quality. The potential of some GF-rice blends in breadmaking has already been studied on blends with prevailing content of rice flour. The impact of added flour may be expected to rise with increasing amount of flour; therefore blends containing 30 g/100 g, 50 g/100 g and 70 g/100 g of GF flour in 100 g of GF-rice blend were tested. Under uniaxial deformation, peak strain was not impacted by the addition of GF flour; stress (12.3 kPa) was, however, significantly (P < 0.05) decreased (2.9–6.2 kPa). The reduction initiated by the presence of buckwheat, chickpea, quinoa and partly amaranth, together with thermally-induced dough weakening initiated by buckwheat and quinoa flour, may be related to significantly better crumb porosity. Overall acceptability of composite breads containing amaranth, chickpea and quinoa was negatively impacted by the aroma and taste of these flours. Higher potential to improve rice dough behavior and bread quality was found in the blend containing buckwheat flour (30 g/100 g; 50 g/100 g). Millet and corn flour deteriorated dough and bread quality.     

Scanning Electron Microscopic Study of Dough and Chapati from Gluten-reconstituted Good and Poor Quality Flour

Hard and soft wheat flours, which were used in the study, resulted in good and poor quality chapatis respectively. Gluten was isolated and interchanged among the two whole wheat flours and studied by scanning electron microscopy for its influence on structural characteristics of dough and its relation to chapati-making quality. Microscopic observations clearly indicated that larger gluten strands covered starch granules in hard wheat flour dough, while gluten was short and starch granules exposed in dough prepared from soft wheat flour. Greater film forming ability of gluten in hard wheat flour dough manifested in long and bulky starch strands interwoven with protein matrix in its chapati crumb. Higher moisture retention and starch gelatinization as a consequence of greater film forming ability of gluten in hard wheat flour resulted in pliable and soft textured chapati.     

Studies on the baking properties of wheat: Pigeonpea flour blends

Pigeonpea flour was substituted at levels of 0, 5, 10, 15,20, 25% to wheat flour and whole wheat meal for bread andChapatti making, respectively. Blends were prepared up to50% for cookie making. Increasing levels of pigeonpeas inthe blends significantly increased the protein and mineralcontent of the baked products. The bread from 10%pigeonpea flour blend with 2–3% vital gluten and 0.5%SSL had high loaf volume and loaf quality. Blends containing 15% pigeonpea flour were acceptable for Chapatti and 30% pigeonpea flour with 0.25% SSL wereacceptable for cookie making.     

Effect of extrusion cooking of sorghum flour on rheology,morphology and heating rate of sorghum–wheat composite dough

Addition of a gluten-free flour such as sorghum has negative impact on the quality of wheat dough for bread making. One of the methods which can be used to promote the quality of sorghum-wheat composite dough is to extrude the sorghum flour before incorporation. In this regard, to produce a dough with appropriate bakery properties sorghum flour was extruded at 110 °C and 160 °C die temperature with 10%, 14% and 18% feed moisture. The effect of extruded sorghum flour incorporation (10%) on rheological (farinography and stress relaxation behavior), morphological and temperature profile of sorghum-wheat composite dough were evaluated. Extrusion cooking altered the sorghum-wheat composite dough properties through partial gelatinization of starch granules. Addition of extruded sorghum flour increased the water absorption and dough development time but it decreased the dough stability. Native sorghum-wheat composite dough showed viscoelastic liquid-like behavior whereas addition of sorghum flour extrudate changed dough to a more viscoelastic solid-like structure. Maxwell model was more appropriate than Peleg model to describe the viscoelasticity of the sorghum-wheat composite dough. Extrusion cooking decreased composite dough elasticity and viscosity. Sorghum extrudate increased the heating rate of composite dough crumb during baking. Addition of extruded sorghum flour formed a non-uniform and less compact dough structure. As a result, dough containing extruded sorghum flour had a good potential for producing a high-yielding bread in a short time of baking.     

Improving the quality of nutrient-rich Teff (Eragrostis tef) breads by combination of enzymes in straight dough and sourdough breadmaking

The growing interest in the benefits of wholegrain products has resulted in the development of baked products incorporating less utilised and ancient grains such as, millet, quinoa, sorghum and teff. However, addition of wholegrains can have detrimental effects on textural and sensory bread product qualities.Enzymes can be utilised to improve breadmaking performance of wholegrain flours, which do not possess the same visco-elastic properties as refined wheat flour, in order to produce a healthy and consumer acceptable cereal product.The effects of Teff grain on dough and bread quality, selected nutritional properties and the impact of enzymes on physical, textural and sensory properties of straight dough and sourdough Teff breads were investigated.Teff breads were prepared with the replacement of white wheat flour with Teff flour at various levels (0%, 10%, 20%, and 30%) using straight dough and sourdough breadmaking. Different combinations of enzymes, including xylanase and amylase (X + A), amylase and glucose oxidase (A + GO), glucose oxidase and xylanase (GO + X), lipase and amylase (L + A) were used to improve the quality of the highest level Teff breads. A number of physical, textural and sensory properties of the finished products were studied. The nutritional value of breads was determined by measuring chemical composition for iron, total antioxidant capacity, protein, fibre and fat. The obtained results were used to estimates intakes of nutrients and to compare them with DRIs.The incorporation of Teff significantly (P < 0.05) improved dietary iron levels as 30% Teff breads contained more than double the amount of iron when compared to corresponding wheat bread (6 mg/100 g v 2 mg/100 g). Addition of Teff also significantly (P < 0.05) improved total antioxidant capacity from 1.4 mM TEAC/100 g to 2.4 mM TEAC/100 g. It was estimated that an average daily allowance of 200 g of Teff enriched bread would contribute to DRIs in the range of 42-81% for iron in females, 72-138% for iron in males; 38-39% for protein in males, 46-48% for protein in females; and 47-50% of fibre in adults.The major challenge was encountered in producing the highest level of Teff bread with good textural and sensory attributes. Increasing the level of Teff significantly (P < 0.05) increased dough development time, degree of softening, crumb firmness and bitter flavour whilst decreasing the dough stability, specific loaf volume and overall acceptability of the bread. Teff breads produced with the addition of enzyme combinations showed significant improvements (P < 0.05) in terms of loaf volume, crumb firmness, crumb structure, flavour and overall acceptability in both straight dough and sourdough breadmaking.     

Effect of sodium chloride on gluten network formation,dough microstructure and rheology in relation to breadmaking

Sodium chloride (NaCl) is an essential ingredient to control the functional properties of wheat dough and bread quality. This study investigated the effect of NaCl at 0, 1 and 2%, (w/w, flour base) on the gluten network formation during dough development, the dough rheology, and the baking characteristics of two commercial flours containing different levels of protein (9.0 and 13.5%) and with different glutenin-to-gliadin ratios. Examination of the dough structure by confocal microscopy at different stages of mixing show that the gluten network formation was delayed and the formation of elongated fibril protein structure at the end of dough development when NaCl was used. The fibril structure of protein influenced the dough strength, as determined by strain hardening coefficient and hardening index obtained from the large deformation extension measurements. NaCl had a greater effect on enhancing the strength of dough prepared from the low protein flour compared to those from the high protein flour. The effect of NaCl on loaf volume and crumb structure of bread followed a similar trend. These results indicate that the effect of NaCl on dough strength and bread quality may be partially compensated by choosing flour with an appropriate amount and quality of gluten protein.     

Mechanical Properties of Bread Crumb Prepared from Flours of Different Dough Strength

Bread quality depends in part on the textural properties of the crumb; softness and strength being two important textural attributes. This study examined differences between instrumentally-measured textural properties of the crumb of bread made from two flours; one possessing extra strong dough mixing characteristics and a second of moderate strength (red spring wheat). Bread crumb specimens, notched and un-notched, were subjected to tensile loading and the crumb's initial (elastic) modulus, stress at failure (crumb strength) and tear resistance were determined. The same mechanical parameters were determined on bread crumb that had been compressed approximately five-fold in order to destroy crumb structure. For un-notched specimens, stiffness and strength were of the order of 11 and 1 kN/m², respectively, whereas after compression they were 230 and 10 kN/m², respectively. For CWRS breadcrumb, toughness increased from 4·1 J/m²to 12·3 J/m²following crumb compression. Bread crumb made from a flour possessing extra strong dough properties was stronger than bread crumb made from a more conventional red spring wheat flour, and there was an indication that extra strong flour bread crumb specimens were stiffer. Compression of the bread crumb lessened the difference between the mechanical properties of the two bread types, particularly for strength and tear resistance. The results indicated that bread crumb structure plays a predominant role in the textural properties of bread crumb.     

Effect of wheat germ flour addition on wheat flour,dough and Chinese steamed bread properties

Wheat germ flour (WGF) has been developed as a functional food ingredient with high nutritional value. In this study, WGF was applied in steamed bread-making in order to improve the quality of Chinese steamed bread (CSB). Partial substitution of wheat flour with WGF at levels of 3%, 6%, 9% and 12% (w/w) was carried out to investigate physicochemical properties of blends and their steaming performance. Falling number (FN) values of composite flours ranged from 199 to 223 s. Viscosity analysis results showed that wheat flour mixed with WGF had higher pasting temperature and lower viscosities. Dough rheological properties were also investigated using farinograph and extensograph. The addition of WGF diluted the gluten protein in dough and formed weak and inextensible dough, which can be studied by scanning electron microscope (SEM) analysis. CSB made with WGF had significantly lower volume, specific volume and higher spread ratio. The sensory acceptability and physicochemical quality of CSB were improved with the application of a low level of WGF (3% and 6%). However, results showed that a high level of WGF over 9% is not recommended because of unsatisfactory taste. As a whole, addition of appropriate level of WGF in wheat flour could improve the quality of CSB.     

Selected nutritional,physical and sensory characteristics of pan and flat breads prepared from composite flours containing fababean

Composite flour blends containing wheat (W), fababean (F), cottonseed and sesame flours were formulated to provide the FAO/WHO/UNU protein requirements for the 2–5 year old child, and evaluated in pan and flat bread applications. Water absorption of composite flour doughs was up to 35% greater than the control but gluten strength and slurry viscosities were markedly reduced. Loaf volume and specific volume of pan breads prepared from composite flours were 25–60% less than that of the control bread but flat breads tolerated the protein supplements extremely well. The W/F flat bread, containing 27% of fababean flour, received acceptable taste, texture and colour scores and was only slightly inferior to the control in puffing and layer separation. Additions of cottonseed or sesame flours to the W/F blend failed to improve sensory properties of the flat breads.     

Impact of lipases with different substrate specificity in wheat flour separation on the properties of the resultant gluten

Wheat gluten was isolated in a laboratory dough-batter flour separation process in the presence or absence of lipases differing in hydrolysis specificity. The obtained gluten was blended with wheat starch to obtain gluten-starch (GS) blends of which the water and oil binding capacities were investigated. Furthermore, GS blends were mixed into dough and processed into model breads, of which dough extensibility and loaf volume were measured, respectively. In comparison to GS blends prepared with control gluten, oil binding capacity was higher when GS blends contained gluten isolated with Lecitase Ultra (at 5.0 mg enzyme protein/kg flour), a lipase hydrolyzing both non-polar and polar lipids. Additionally, dough extensibility and total work needed for fracture were lower for dough prepared from GS blends containing gluten isolated with Lipolase (at 5.0 mg enzyme protein/kg flour), a lipase selectively degrading non-polar lipids. In GS blend bread making, this resulted in inferior loaf volumes. Comparable GS blend properties were measured when using control gluten and gluten isolated with YieldMAX, a lipase mainly degrading N-acyl phosphatidylethanolamine. In conclusion, properties of GS blend model systems are altered when gluten prepared in the presence of lipases is used to a degree which depends on lipase specificity and concentration.     

Wheat (Triticum aestivum L.) puroindoline functionality in bread making and its impact on bread quality

Wheat puroindolines (PINs) spontaneously adsorb at air/water interfaces and show excellent foaming properties. They can positively impact bread quality, in which the formation of stable foam is important for product quality. The impact of endogenous PINs on bread quality was studied by preparing gluten–starch blends from isolated gluten and starch fractions with different PIN levels, which allowed largely retaining the interaction between PINs and flour components. Our results indicate that blends with high PIN levels yielded more homogeneous crumb structures with fine gas cells than bread made with blends containing medium or low PIN levels. However, the mechanism by which PINs exert this crumb improving effect is not clear. Varying PIN levels impacted neither dough extensibility nor did it result in different PIN levels in dough liquor. Lipid removal yielded bread with a less homogeneous crumb gas cell distribution, indicating that lipids also are required to obtain good crumb structure.     

Rheological properties and baking performance of rye dough as affected by transglutaminase

Since protein aggregation and formation of a continuous protein matrix in rye dough is very limited, an enzyme-induced protein aggregation method to improve the baking properties was investigated. The effects of microbial transglutaminase (TG) on the properties of rye dough were studied by rheological tests, confocal laser scanning microscopy (CSLM), standard-scale baking tests and crumb texture profile analysis. Addition of TG in the range of 0-4000 Ukg⁻¹ rye flour modified the rheological properties of rye flour dough, resulting in a progressive increase of the complex shear modulus (|G∗|) and in a decrease of the loss factor (tan δ) due to protein cross-linking or aggregation. CLSM image analysis illustrated a TG-induced increase of the size of rye protein complexes. Standard baking tests showed positive effects on loaf volume and crumb texture of rye bread with TG applied up to 500 Ukg⁻¹ rye flour. Higher levels of TG (500 U ≤ TG ≤ 4000 U) had detrimental effects on loaf volume. Increasing TG concentration resulted in an increase of crumb springiness and hardness. In conclusion, the results of this work demonstrated that TG can be used to improve the bread making performance of rye dough by creating a continuous protein network.     

Effect of pre-dehulling treatments on the composition of seeds of the legumeAfzelia africana and its potential use in pastries

Flour was prepared from seeds ofAfzelia africana dehulled by different treatments and used to replace 10, 20, 30, 40 and 50% wheat flour in biscuits and doughnuts. The composition and water and oil absorption properties of the flour blends were evaluated. The biscuits and doughnuts made from each flour blend were evaluated organoleptically. The composite flour containing the highest proportion (50%) ofA. africana seed flour contained the highest levels of protein and fat, exhibited the highest water absorption property but the lowest oil absorption capacity. Sensory scores showed high overall acceptability for products with a 10–30% level of substitution.     

Grain of high digestible,high lysine (HDHL) sorghum contains kafirins which enhance the protein network of composite dough and bread

The aim of this study was to determine whether protein body-free kafirins in high digestibility, high-lysine (HDHL) sorghum flour can participate as viscoelastic proteins in sorghum-wheat composite dough and bread. Dough extensibility tests revealed that maximum resistance to extension (g) and time to dough breakage (sec) at 35 °C for HDHL sorghum-wheat composite doughs were substantially greater (p < 0.01) than for normal sorghum-wheat composite doughs at 30 and 60% substitution levels. Functional changes in HDHL kafirin occurred upon exceeding its T_g. Normal sorghum showed a clear decrease in strain hardening at 60% substitution, whereas HDHL sorghum maintained a level similar to wheat dough. Significantly higher loaf volumes resulted for HDHL sorghum-wheat composites compared to normal sorghum-wheat composites at substitution levels above 30% and up to 56%, with the largest difference at 42%. HDHL sorghum-wheat composite bread exhibited lower hardness values, lower compressibility and higher springiness than normal sorghum-wheat composite bread. Finally, HDHL sorghum flour mixed with 18% vital wheat gluten produced viscoelastic dough while normal sorghum did not. These results clearly show that kafirin in HDHL sorghum flour contributes to the formation of an improved protein network with viscoelastic properties that leads to better quality composite doughs and breads.     

小麦不同阶段产品品质性状的变异及其关系

为给小麦籽粒、面粉和面团三个不同阶段产品品质性状的改良提供依据以来源于同一组合的48个小麦稳定品系为试验材料,2014-2015年分别在关中东部川道高肥区、关中西部塬区中肥区条件下,研究了小麦籽粒、面粉和面团的12个品质性状在品系间和环境间的变异及其性状间的关系。结果表明,在品系间,籽粒、面粉和面团分别以蛋白质含量、沉降值和最大抗延伸阻力的变异系数最大;在环境间,籽粒、面粉和面团性状则分别以硬度、沉降值和拉伸面积变异系数最大。性状变异在不同产品阶段和条件下表现为：面团>面粉>籽粒,品系间>环境间,品系和环境对大部分性状有极显著影响。籽粒含水量与面粉和面团的大部分性状呈负相关;籽粒硬度与面粉性状指标呈正相关,与面团性状指标相关不显著;籽粒容重对面粉和面团性状影响较小;籽粒蛋白质含量与面粉和面团的多个指标呈正相关。面粉湿面筋含量和面粉沉降值与面团延展性、抗延伸阻力、稳定时间、形成时间和拉伸面积均呈显著正相关;面粉吸水率与面团延展性呈显著正相关。籽粒对面团品质指标的决定系数为0.108 5~0.517 9,面粉对面团品质指标的决定系数为0.618 4~0.873 0。面粉品质较籽粒品质对面团品质影响更大。