Rheological Properties Of Wheat Flour Research Articles

Effect of resistant starch (RS3) addition on rheological properties of wheat flour

AbstractThe rheological properties of wheat flour (WF) mixed with RS type 3 at different concentrations of RS (0, 5, 10, 15, and 20%) were examined. Steady and dynamic shear rheological tests indicated that the magnitudes of consistency index (K), apparent viscosity (ηa,100), dynamic modulus (G′ and G″), and complex viscosity (η*) of the WF–RS mixtures decreased with an increase in the mixing concentration of RS. G′ values of WF–RS mixture samples except for 5% RS as a function of aging time (14 h) at 5°C increased rapidly at initial stage and then reached a plateau region at long aging times. Increasing the RS concentration resulted in the decrease in plateau values. In general, these results suggest that the presence of RS in WF modifies the rheological properties, and that these modifications are dependent on the concentration of RS. The most pronounced changes of viscoelastic properties were observed for WF mixed with 20% RS.

Effect of superfine green tea powder on the thermodynamic, rheological and fresh noodle making properties of wheat flour

Superfine green tea powder (SGTP) was used to substitute 0g, 1g, 2g, and 3g of 100g wheat flour (defined as 0SGTP, 1SGTP, 2SGTP and 3SGTP respectively) to make fresh noodles. The effects of SGTP on the viscosity, thermodynamic and rheological properties of wheat flour were evaluated, as well as the sheet colour, cooking quality, texture properties and sensory characteristics of green tea noodles. The results revealed that the stability, elastic modulus (G′) and viscous modulus (G″) of wheat dough all increased with the increase of green tea powder proportion. No significant differences were found in gelatinisation properties of the green tea-flour systems. Furthermore, adding SGTP could significantly (P<0.05) retard the retrogradation of the gelatinised wheat flour gel. L∗ value of fresh noodles decreased as SGTP content increased while |a∗| value firstly increased and then decreased at 3g/100g. The 2SGTP noodle samples showed the least cooking loss. Sensory evaluation indicated that the control and the 2SGTP fresh noodles scored significantly (P<0.05) higher in terms of colour. No significant difference was detected for the mouthfeel and overall acceptability among all samples.

Cloning, Prokaryotic Expression, and Functional Testing of a γ-Gliadin Gene from Wheat Cultivar Shaan 253

The γ-gliadin gene (GenBank accession No. GQ857626) was isolated from a wheat (Triticum aestivum) cultivar with a hight quality Shaan 253, using inductuion a set of genome specific primers. The deduced amino acid sequence of GQ857626 exhibited an additional cysteine residue in the region II of mature γ-gliadin subunits compared to the previous report. A prokaryotic expression vector was constructed to express GQ857626 in the host bacterium Escherichia coli Rosetta-gami B(DE3). The SDS-PAGE and Western blot analysis confirmed that the fusion protein was expressed by induction of 0.1 mmol L^(-1) isopropyl-β-D-thiogalactoside (IPTG), and its actual molecular weight was about 50 kD nearly equal to the predicted. After separation and purification using HisTrap HP affinity chromatography, the function of fusion protein was tested by means of micro 4 g farinograph. When the subunit of GQ857626 was integrated into the control flour through oxidation-reduction reaction, many important farinograph parameters changed drastically, such as development time, dough stabilizing time, degree of softening. Although the gluten strength of the control flour could be improved in some degree, the subunit of GQ857626 showed a negative effect on the rheological properties of wheat flour.

Rheological properties of wheat flour substitutes/alternative crops assessed by Mixolab

Wheat is one of the most common cereals used in the world. However, due to greater public awareness of celiac disease and gluten intolerance as well as consumers demands for healthy food and variety in food products, in many widely consumed staples, such as bread, wheat flour is fully or partially replaced with flour from other cereals, pseudocereals or legumes. Although wheat flour alternatives are readily available in the market, these products are often of inferior quality. The aim of this paper was to predict the suitability of alternative crops such as rice, corn, buckwheat, amaranth and soya for the production of quality bread. Their rheological properties were studied, and compared to the properties of wheat flour which served as a benchmark. The tested alternative cereals, pseudocereals and legumes were selected in order to represent the widely used ones in gluten-free products as well as the ones found to be nutritionally improved according to recent publications. Moreover, the differences between wheat and buckwheat flour, and their wholegrain counterparts were also studied. The determination of rheological properties of wheat flour dough as well as the dough from other raw materials (rice, corn, buckwheat, amaranth and soya) was performed by Mixolab. According to results obtained by Mixolab measurements, flours from different raw materials exhibited Mixolab profiles which greatly differ from wheat flour profile. Samples of rice and both types of buckwheat flour expressed the most similar rheological behaviour to wheat flour. However, since, there was no tested material which exactly mimic wheat flour dough properties, it was concluded that their mixtures would give the optimal rheological profile. Although it is a very challenging task to mimic wheat flour unique breadmaking properties, it is possible to create products having similar rheological behaviour to wheat flour dough, but improved functional properties.

Efeito do período de maturação de grãos nas propriedades físicas e reológicas de trigo

O trabalho objetivou estudar o efeito do período de maturação de grãos nas propriedades físicas e reológicas da farinha de trigo, avaliado através das determinações de peso do hectolitro, peso de mil grãos, grau de extração, proteínas, cinzas, umidade, cor, número de queda, alveografia, farinografia e amido danificado. Amostras dos genótipos BRS 179, Rubi, Fundacep 30 e Fundacep 51, safra 2006/2007 foram armazenadas em sacos de papel Kraft com 10 kg de trigo, em ambiente com temperatura de 22 °C e umidade relativa do ar de 65-75%. Cada tratamento foi composto por um genótipo e as avaliações realizadas nos tempos 0, 15, 30, 60 e 90 dias de maturação. O experimento foi conduzido em delineamento inteiramente casualizado em arranjo fatorial 4 x 5. Os resultados foram analisados pelo emprego da análise de variância (Anova) e nos modelos significativos pelo teste F, e a comparação de médias pelo teste de Tukey a 5% de probabilidade. Com o aumento do período de maturação do trigo a farinha apresentou melhores propriedades físicas e reológicas avaliadas pelas alterações de número de queda, cor, alveografia e farinografia. Os resultados de atividade enzimática, luminosidade, intensidade de amarelo e força geral do glúten se mostraram efetivos na avaliação de propriedades físicas e reológicas, enquanto as avaliações de amido danificado e estabilidade não foram indicadores adequados. O trigo não deve ser comercializado após a colheita, pois apresenta melhoria na classificação comercial, sendo indicado período de maturação de 60 dias. Os genótipos de trigo BRS 179 e Fundacep 51 passaram das classes brando para pão, enquanto o Rubi de pão para melhorador, indicando maior valor tecnológico e comercial com o aumento do período de maturação dos grãos de trigo.

IMPROVEMENT OF DOUGH RHEOLOGY AND BREAD QUALITY BY ENZYMES COMBINATION

In present, most mills from our country obtain brown wheat flour in intermediate extraction, besides white flour, and its quality is mostly inadequate and unconstant. Our paper's purpose was the&#x0D; optimization of the brown wheat flour's quality with the help o enzymes, using some of its beneficial properties. The sinergic effect of Aspergillus niger laccase and phytase, and cereal ?-amylase (Belpan) on the rheological properties of wheat flour were examined with the Mixolab test. The bread obtained from wheat flour with laccase and ?-amylase displayed an increased volume, without the problem of soaking during processing,&#x0D; compared with the bread obtained from the witness sample. An indirect correlation between falling number values and Belpan doses was obtained.

Rheological properties of wheat flour processed at low levels of hydration: Influence of starch and gluten

The rheological properties of wheat flour under processing such as extrusion (with 28% moisture content, wet basis) are influenced by the molecular changes its components undergo during processing. But, there was no simple relationship between the wheat-flour characteristics and their rheological properties. In order to investigate the quantitative and qualitative effects of the individual flour components on rheological properties, model blends of wheat starch and wheat gluten with different starch/gluten ratios were studied. The effects of gluten and starch quality were also investigated by using different gluten types and by modifying the amylose content of starch, respectively. The shear viscosity of the blends, determined by capillary rheometry under controlled conditions (35% moisture content, 140 °C), was observed to be modified by both gluten and amylose content. The changes undergone by wheat gluten under these conditions were analysed by HPLC, to determine the levels of unextractable polymeric proteins, and by Lab-on-a-Chip analysis of protein composition, to follow the polymerisation of protein under processing. This study indicated that in low hydrated products in the molten state, shear viscosity is affected by the structure of the blends as determined by fluorescence microscopy and by the molecular changes occurring during processing.

Hydrolysis of wheat flour with amylase preparations and individual enzymes

Rheological properties of wheat flour were studied in the course of its processing (cooking and saccharification). The effects of commercial alpha-amylase preparations were compared during flour preparation. Test preparations were equally potent in decreasing the viscosity of an all-grain batch. Homogenous glucoamylases isolated from Aspergillus differed in the presence or absence of the starch-binding domain. The starch-binding domain provided for the high activity of glucoamylase on insoluble starch, but gave no advantages in saccharification of pretreated wheat flour.

Effect of l‐Cysteine on the Rheological Properties of Wheat Flour

ABSTRACTExtrudate expansion of cereal‐based products is largely dependent on the molecular interactions and structural transformations that proteins undergo during extrusion processing. Such changes strongly influence the characteristic rheological properties of the melt. It is possible to modify rheological properties of wheat flour during extrusion processing, in particular shear viscosity, with cysteine. The objective of this work was to further develop an understanding of the molecular interactions and structural transformations of wheat flour from dynamic oscillatory rheological measurements. Temperature and frequency sweeps were conducted in the linear viscoelastic range of the material. Changes in the storage modulus (G′), the loss modulus (G″) and the loss tangent (tan δ) of 25% moisture wheat flour disks as a function of cysteine concentration (0–0.75%) were monitored. Molecular weight between cross‐links (Mc) and the number of cross‐links (Nc) per glutenin molecule were determined from frequency sweep data. Increasing cysteine concentration broke cross‐links by decreasing G′ maximum and increasing tan δ values. Molecular weight between cross‐links increased and the number of cross‐links decreased. G′ values from temperature sweeps showed a similar trend. This information leads to a better understanding of the viscoelastic behavior of wheat flour doughs during extrusion cooking and elucidation of protein‐protein reaction mechanisms and other interactions in extruded cereal‐based snack foods.

食品保存へのオゾンの利用に関する研究 （第７報） 小麦粉へのオゾン処理が生地の物理化学的特性に及ぼす影響

食品保存へのオゾンの利用に関する研究 （第７報） 小麦粉へのオゾン処理が生地の物理化学的特性に及ぼす影響

LITERATURE ABSTRACTS

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Effect of Malonaldehyde on the Rheological Properties of Wheat Flour

AbstractThe addition of malonaldehyde (MA) results in significant changes in the visco‐elastic behaviour of wheat flour dough. Incorporation of MA in wheat flour also enhances its rate of maturation during subsequent storage. After storage, MA treated wheat flour had lesser extensibility and higher resistance, dough development time and stability than the untreated sample. Altered visco‐elastic behaviour of wheat flour has been explained by the reaction of MA with sulphohydryl and amino groups.

Tress Relaxation of Synthetic Flour Doughs

Stress relaxation behaviours of synthetic flour doughs, prepared by mixing the major components of wheat flour such as gluten protein and wheat starch granule with water, have been measured to obtain informations on the factors affecting the rheological properties of wheat flour dough.A slow relaxation phenomenon appears in the synthetic systems under a constant normal strain, and this is not very much influenced by addition of reducing glutathione which may induce an interchange reaction between thiol groups and disulfide bonds in the gluten protein. The presence of wheat starch granule plays an important role not only in cementation of dough but also in exhibition of non-linear viscoelastic behaviour. The results obtained are considered to arise from the formation of a weak scaffolding structure of starch granules in the dough system.

Physicochemical properties of S-zone and base proteins in gluten.

Some of the physicochemical properties (solubility, viscosity, sedimentation) and the amino acid composition of the isolated S-zone and base proteins from soft-wheat gluten were studied. The S-zone proteins are homogeneous in size, of low molecular weight (about 20,000), and high intrinsic viscosity in buffer of pH 3,5, having stable structures whose unique solubility properties are related to their atypical amino acid content. The base protein molecules exist in a more folded conformation, having the properties of globular protein molecules. The protein–protein interactions, aggregation, and unfolding conformation of S-zone proteins are major contributing factors at neutral pH to the rheological properties of wheat flour, such as viscosity, elasticity, and cohesiveness.