Gelatinization,Pasting, and Gelling Properties of Sweetpotato and Wheat Starch Blends

Sweetpotato starch is high yielding but has very limited uses. It is possible to expand its application by blending it with other starches to obtain novel properties. In this study, functional properties of the blends of native sweetpotato starch with native, acid‐thinned, and hydroxypropylated wheat starch were studied at different ratios (75:25, 50:50, 25:75). The swelling factor, extent of amylose leaching, pasting, and gel textural properties of the blends were nonadditive of their individual components, and could be mathematically modeled by quadratic equations in relation to the ratios. Two peaks during pasting were observed for some starch mixtures studied by Rapid ViscoAnalyser (RVA). The gelatinization and retrogradation enthalpies (ΔH) of the blends were additive of their individual components and could be modeled by linear equations. All starch mixtures exhibited two peaks during differential scanning calorimetry (DSC) scan for gelatinization, but a single peak for retrograded starches. This study may provide basis for formulation of mixtures using starch from diverse sources to develop more natural starch systems with a range of physicochemical properties.     

Diversity of Starch Pasting Properties in Iranian Hexaploid Wheat Landraces

Wheat landraces possess a wide diversity in starch physical properties that could be useful in breeding for improved quality of specific products, such as various types of Asian noodles. The pasting properties (using a Rapid Visco-Analyser [RVA]) and flour swelling volume (FSV, using silver nitrate to inactivate α-amylase activity) of wholemeal, were measured for 242 hexaploid accessions of Iranian landrace wheat. FSV values and the peak viscosities were positively correlated (r = 0.73***). FSV values in the landraces ranged from 8.3 to 15.9 mL/g and peak viscosities ranged from 139 to 305 RVA units (RVU). In comparison, FSV of cvs. Eradu and Klasic were 18.6 and 15.0 mL/g, and peak viscosities were 355 and 303 RVU, respectively. Of the landraces, Iranian Wheat Accession (IWA) 8602488 had the highest peak viscosity (305 RVU) and exceptionally high hot- and cool-paste viscosities. Two accessions, IWA 8602430 and 8600544, displayed pasting characteristics considered desirable for high-quality Japanese white-salted noodles. Four landraces were identified that had starch with unusually high resistance to shearthinning. Texture profile analysis was done on the wholemeal gels formed in the RVA canister. The variation in parameters such as hardness, chewiness, and adhesiveness in the landraces greatly exceeded that in the cultivars. The hot-paste viscosity, breakdown, setback, and final viscosity values, but not the peak viscosity or FSV, were highly significantly correlated with the hardness, chewiness, and adhesiveness of the gel. The Iranian landraces appear to present useful genetic variation for developing wheats for special uses.     

Sources of Variation for Starch Gelatinization,Pasting, and Gelation Properties in Wheat

The starch of wheat (Triticum aestivum L.) flour affects food product quality due to the temperature-dependent interactions of starch with water during gelatinization, pasting, and gelation. The objective of this study was to determine the fundamental basis of variation in gelatinization, pasting, and gelation of prime starch derived from seven different wheat cultivars: Kanto 107, which is a partial waxy mutant line, and six near-isogenic lines (NILs) differing in hardness. Complete pasting curves with extended 16-min hold at 93°C were obtained using the Rapid Visco Analyser (RVA). Apparent amylose content ranged from 17.5 to 23.5%; total amylose content ranged from 22.8 to 28.2%. Starches exhibited significant variation in onset of gelatinization. However, none of the parameters measured consistently correlated with onset or other RVA curve parameters that preceded peak paste viscosity. Peak paste viscosity varied from 190 to 323 RVA units (RVU). Higher peak, greater breakdown, lower final viscosity, negative setback, and less total setback were associated with lower apparent and total amylose contents. Each 1% reduction in apparent or total amylose content corresponded to an increase in peak viscosity of about 22 and 25 RVU, respectively, at 12% starch concentration. Of the seven U.S. cultivars, the lower amylose cultivars Penawawa and Klasic were missing the granule-bound starch synthase (GBSS; ADPglucose starch glycosyl transferase, EC 2.4.4.21) protein associated with the Waxy gene locus on chromosome 4A (Wx-B1 locus). Kanto 107 was confirmed as missing both the 7A and 4A waxy proteins (Wx-A1 and Wx-B1 loci). The hardness NIL also were shown to be null at the 4A locus. Apparent and total amylose contents of prime starch generally corresponded well to the number of GBSS proteins; although the hardness NIL tended to have somewhat higher amylose contents than did the other GBSS 4A nulls. We concluded that reduced quantity of starch amylose due to decreased GBSS profoundly affects starch gelatinization, pasting, and gelation properties.     

Effect of Surfactant Structure on the Pasting Properties of Wheat Flour and Starch Suspensions

Systematic studies were performed on the effect of the surfactant alkyl chain length (10–16 carbon atoms) and the head group charge/structure (anionic, cationic, nonionic) on the pasting properties of wheat flour and starch aqueous suspensions by means of a Rapid Visco Analyser (RVA). An excellent agreement was observed between the effect of surfactants on the onset temperature of the pasting process (PT) and the time to reach peak viscosity (t_peak) of wheat flour and wheat starch suspensions. Moreover, a correlation was found between the effect of different surfactants on these two parameters. With the exception of the cationic surfactants (alkyl trimethyl ammonium bromides), the effect of surfactants (alkyl sulfates, maltosides, monoglycerides, and sucrose esters) was found to be strongly dependent on the surfactant chain length. Shorter chain surfactants (C10–C12) induced an earlier pasting, while longer chain surfactants (C14–C16) had the opposite effect. The effect of surfactants on PT and t_peak of flour suspensions was enlarged when the surfactant concentration was increased from ≈1% to 15% (w/w) on a dry starch basis.     

Structure and Pasting Properties of Oat Starch

Following a period of declining food use, oats are now increasing in importance because of perceived nutritional benefits. The pasting properties of oat starch were regarded as similar to those of other cereal starches until the development of instruments with a more rapid mixing system than the amylograph showed characteristic differences in oats. These differences in pasting properties offer opportunities for novel products in both food and industrial areas. The structure, composition, and pasting properties of oat starch are reviewed, with particular emphasis on methods of measurement. Future directions of research in this area are suggested.     

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.     

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.     

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 Added Minerals on Pasting of Partial Waxy Wheat Flour and Starch and on Noodle Making Properties

Mineral content, as determined and expressed by ash content, serves as an index of wheat flour quality for flour millers and food manufacturers who prefer flour of low mineral content, even though the significance of mineral content on the functional properties of wheat flour is not well understood. We explored whether minerals have any influence on the functional properties of wheat flour and product quality of white salted noodles. Ash, obtained by incinerating wheat bran, was incorporated into two hard white spring wheat flours and their starches to raise the total ash content to 1, 1.5, or 2%. Pasting properties were determined using a rapid visco analyzer (RVA). Addition of ash increased the peak viscosity of the flours in both water and buffer solution but did not affect the peak viscosity of starch. Wheat flours with added ash showed lower pasting temperature by approximately 10°C in buffer solution. Mineral extracts (15.3% ash) isolated from wheat bran, when added to increase the ash content of wheat flour and starch to 2%, increased the peak viscosity and lowered the pasting temperature of flour by 13.2–16.3% but did not affect the pasting properties of the isolated starch. The mineral premix also increased peak viscosity of wheat flour but not in starch. Added ash increased noodle thickness and lowered water retention of cooked noodles while it exhibited no significant effect on cooked noodle texture as determined using a texture analyzer.     

Effect of Transglutaminase on Properties of Glutenin Macropolymer and Dough Rheology

The effect of transglutaminase (TG) on glutenin macropolymer (GMP) properties could help to understand changes in bread quality. The aim of the present study was to analyze modifications in GMP and dough properties caused by TG addition. Transglutaminase introduced cross‐links to gluten proteins, mainly high molecular weight glutenins. This effect modified the protein structure and markedly increased dough strength. These changes in the structure of glutenins increased SDS solubility and decreased GMP content and GMP storage modulus. However, TG increased GMP particle size, notably at higher doses. TG affected rheological characteristics of dough in that increasing TG doses decreased tan δ, and increased G'. In all the studies conducted, the TG increased GMP polymer size, but contrary to what was expected, this increase did not involve an increase in GMP content. These results confirmed the effect of TG on dough quality and the great differences found with different TG doses.     

Effect of Damaged Starch and NaCl Level on the Dough Handling Properties of a Canadian Western Red Spring Wheat

The effects of damaged starch and NaCl (1 and 2% w/w [flour weight]) on the dough handling properties of a wheat flour (Triticum asetivum L. ‘Roblin’) were investigated with rheological and textural methods. Damaged starch levels of the base flour and three remilled flours (using reduction rolls with decreasing gap sizes) were 5.42, 6.23, 7.30, and 8.43%. Rheological measurements on the dough showed that the complex modulus increased and the loss tangent (tan δ) decreased with increasing damaged starch levels in the flour, indicating that greater amounts of damaged starch produced stiffer dough. The base flour produced doughs with the highest creep compliance value (J _max), whereas the flour with the most damaged starch deformed the least. Higher levels of salt produced stiffer dough that deformed less, as evident by the higher complex modulus and lower creep compliance, compared with 1% NaCl. Damaged starch overall decreased dough stickiness (N), work of adhesion (N·s), and cohesiveness (mm). Increasing the salt content decreased the stickiness of the doughs. Increasing the damaged starch greatly increased dough extensibility at 1% NaCl. The greater amounts of damaged starch in the remilled flour mitigated some of the negative effects of reducing the salt content on the dough machinability.     

Gelatinizing,Pasting, and Gelling Properties of Potato and Amaranth Starch Mixtures

Physicochemical properties of mixtures of native potato and native amaranth (Amaranthus cruentus), heat‐moisture treated (HMT) potato and heat‐moisture treated amaranth, cross‐linked potato and cross‐linked amaranth, native potato and heat‐moisture treated amaranth, and heat‐moisture treated potato, and native amaranth were tested at different ratios. Two peaks were noticed in the pasting curves when large differences of swelling factor and amylose leaching existed between individual components in the mixture. It seems that amylose leaching from one starch in a mixture may affect the swelling and much of the granular break down of the other. The mixtures showed stabilities in hot pastes that were higher than the less stable components in a mixture. Some mixtures such as HMT potato and native amaranth showed very specific nonadditive pasting behavior. Mixing 10% of native amaranth to HMT potato starch caused a large reduction of peak viscosity and cold paste viscosity, resulting in a very soft gel. In the differential scanning calorimeter, each component of a mixture gelatinized independently, showing two peaks corresponding to the individual components. When transition temperatures of both components were similar in DSC, the result was a single endotherm. Dramatic changes of pasting and subsequent gel properties resulted when thermal transition of the two components occurred in the same temperature range. Retrogradation enthalpies as measured by DSC were between the two individual components in all tested mixtures.     

Comparison of Small and Large Deformation Rheological Properties of Wheat Dough and Gluten

The rheological properties of dough and gluten are important for end‐use quality of flour but there is a lack of knowledge of the relationships between fundamental and empirical tests and how they relate to flour composition and gluten quality. Dough and gluten from six breadmaking wheat qualities were subjected to a range of rheological tests. Fundamental (small‐deformation) rheological characterizations (dynamic oscillatory shear and creep recovery) were performed on gluten to avoid the nonlinear influence of the starch component, whereas large deformation tests were conducted on both dough and gluten. A number of variables from the various curves were considered and subjected to a principal component analysis (PCA) to get an overview of relationships between the various variables. The first component represented variability in protein quality, associated with elasticity and tenacity in large deformation (large positive loadings for resistance to extension and initial slope of dough and gluten extension curves recorded by the SMS/Kieffer dough and gluten extensibility rig, and the tenacity and strain hardening index of dough measured by the Dobraszczyk/Roberts dough inflation system), the elastic character of the hydrated gluten proteins (large positive loading for elastic modulus [G′], large negative loadings for tan δ and steady state compliance [J_e⁰]), the presence of high molecular weight glutenin subunits (HMW‐GS) 5+10 vs. 2+12, and a size distribution of glutenin polymers shifted toward the high‐end range. The second principal component was associated with flour protein content. Certain rheological data were influenced by protein content in addition to protein quality (area under dough extension curves and dough inflation curves [W]). The approach made it possible to bridge the gap between fundamental rheological properties, empirical measurements of physical properties, protein composition, and size distribution. The interpretation of this study gave indications of the molecular basis for differences in breadmaking performance.     

Demixing in Wheat Doughs—Its Influence on Dough and Gluten Rheology

Reshaping of relaxed wheat doughs leads to an increase in firmness that significantly changes the results of rheological measurements involving large uniaxial deformations of the dough, whereas the gluten properties remain unaffected. Microscopic investigations reveal that directly after kneading, starch and gluten are thoroughly mixed. However, the shaping procedure of a relaxed dough or shear-flow during rheological measurements cause a separation of gluten and starch. The dilatant behavior of the starch granules and the capacity of gluten to aggregate account for the observed dough-hardening.     

Effect of Wheat Bran on Dough Rheology and Final Quality of Chinese Steamed Bread

Wheat bran is a low‐cost by‐product abundantly produced by the wheat flour industry. As a staple food of China, Chinese steamed bread (CSB) represents about 40% of China's wheat consumption. This study investigated the effects of incorporating wheat bran into the CSB at different levels (5, 10, and 15%). The dough behavior was measured by analyzing rheological properties. Quality of CSB was analyzed from two perspectives: physical properties and nutritional quality. For physical properties, specific volume, loaf height, moisture, and texture were measured by 1 . The predicted glycemic response of the bread was analyzed by using an in vitro digestion method. The results illustrated that the incorporation of wheat bran into wheat flour reduced the extensibility of the dough, decreased specific volume, and increased bread hardness, gumminess, and chewiness. However, this study also showed that addition of wheat bran can decrease the predicted glycemic response of steamed bread by up to 39%.     

Effect of Physical States of Nonpolar Lipids on Rheology,Ultracentrifugation, and Microstructure of Wheat Flour Dough

In the previous study, we investigated effect of physical state of nonpolar lipids of gluten‐starch model dough. This experiment examined a real wheat flour dough system to assess the role of fat crystals in the breadmaking processes. These experiments were performed with a baking test and an investigation of wheat flour dough through rheological measurements (both large and small deformations), scanning electron microscopy, and ultracentrifugation. As a result, we found that the added oil was absorbed in the gluten structure, causing the aggregation of the gluten, which gave rise to more elastic behavior. In contrast, solid fat seemed to be distributed uniformly between the starch granules in the dough, reducing the friction between the starch granules and facilitating thin gluten gel layers. These properties lead to the lower G′ value and the increased viscous behavior, which yields an increase in loaf volume. In addition, the supposed mechanism behind the large loaf volume described in the previous study was that fat provides a uniform distribution of the dough components, and that the dough can thus expand easily, resulting in a larger loaf volume, which was supported in the wheat flour dough system. In conclusion, we found that thin, expandable gluten films and the uniform dispersion of gluten and starch granules in the dough are prerequisites for attaining better baking performance.     

Factors Governing Pasting Properties of Waxy Wheat Flours

Waxy wheat (Triticum aestivum L.) contains endosperm starch lacking in amylose. To realize the full potential of waxy wheat, the pasting properties of hard waxy wheat flours as well as factors governing the pasting properties were investigated and compared with normal and partial waxy wheat flours. Starches isolated from six hard waxy wheat flours had similar pasting properties, yet their corresponding flours had very different pasting properties. The differences in pasting properties were narrowed after endogenous α‐amylase activity in waxy wheat flours was inhibited by silver nitrate. Upon treatment with protease, the extent of protein digestibility influenced the viscosity profile in waxy wheat flours. Waxy wheat starch granules swelled extensively when heated in water and exhibited a high peak viscosity, but they fragmented at high temperatures, resulting in more rapid breakdown in viscosity. The extensively swelled and fragmented waxy wheat starch granules were more susceptible to α‐amylase degradation than normal wheat starch. A combination of endogenous α‐amylase activity and protein matrix contributed to a large variation in pasting properties of waxy wheat flours.     

Effects of Salt,Polyethylene Glycol,and Water Content on Dough Rheology for Two Red Spring Wheat Varieties

In this research, the relationship between dough rheology and water behavior was investigated in response to two osmotic regulators, salt (NaCl) and polyethylene glycol (PEG), using two Canadian Western Red Spring (CWRS) wheat varieties (Harvest and Pembina). The effects of NaCl (0.5, 1.0, and 1.5 g/100 g of flour) and PEG 400 (2.5, 5.0, and 7.5 g/100 g of flour) on dough rheology (oscillatory and creep) were estimated by using a central composite design. Variation of NaCl showed a significant effect on the phase angle δ, indicating that increasing the NaCl resulted in a more elastic dough. The opposite trend was observed with the addition of PEG. PEG 400 exerted a softening effect owing to plasticization, so that a more compliant liquid‐like dough was produced. The effects of water content (±10% of farinograph absorption) and PEG molar mass on dough rheology and freezable water content were estimated by using a full factorial design. PEGs with different molar mass (400, ≈1,600, and 3,350 g/mol) were added at a concentration of 1 g/100 g of flour. The water content significantly affected all dough rheological attributes, whereas PEG molar mass had no effect. The complex shear modulus (G* ) decreased with increasing water content, and dough creep compliance (J _max) increased. The elastic response of dough, determined as the relative elastic part (J _el) decreased with increasing water content. A high correlation was found between the freezable water content and dough rheological attributes.     

Effect of Ferulic Acid and Catechin on Sorghum and Maize Starch Pasting Properties

The effects of ferulic acid and catechin on starch pasting properties were studied as part of an investigation into the structure and functionality of phenolics in starch‐based products. Commercial maize starch, starches from sorghum cultivars (SV2, Chirimaugute, and DC‐75), and the phenolic compounds ferulic acid and catechin were used in the investigation. Pasting properties were measured using rapid viscosity analysis. Ferulic acid and catechin (up to 100 mg each) were added to maize or sorghum starch (3 g, 14% mb) in suspensions containing 10.32% dry solid content. Addition of catechin resulted in pink‐colored pastes, whereas ferulic acid had no effect on paste color. Ferulic acid and catechin decreased hot paste viscosity (HPV), final viscosity, and setback viscosity of maize and sorghum starch pastes, but had no influence on the peak viscosity (PV) of the former. Both phenolics increased breakdown viscosity. Ferulic acid had greater influence on HPV, final viscosity, breakdown, and setback than catechin. Addition of catechin under acidic conditions (pH 3) decreased HPV, final viscosity, and setback of maize starch, but alkaline conditions (pH 11) slightly increased setback. Both acidic and alkaline conditions resulted in increased breakdown. Investigations on model‐system interactions between ferulic acid or catechin and starch demonstrated that phenolic type and pH level both significantly influence starch pasting properties, with ferulic acid producing a more pronounced effect than catechin. The significance of these interactions is important, especially in food matrices where phenolics are to be added as functional food ingredients.     

Increase in Apparent Amylose Content and Change in Starch Pasting Properties at Cool Growth Temperatures in Mutant Wheat

Some mutant wheat lines with low‐amylose content were grown in a field and greenhouse (15 or 20°C) to compare apparent amylose content and starch pasting properties. The apparent amylose content of flour and starch increased and starch pasting parameters as measured by a Rapid Visco Analyser (RVA) changed in the greenhouse (at cool temperatures) during seed maturation. Densitometric analysis of the protein band separated by electrophoresis suggested that the increase in amylose content by cool temperature was related to the amount of Wx‐D1 protein. This data suggests that the Wx‐D1 gene was responsible for these changes. In wheat starch from Tanikei A6099 and Tanikei A6598 at 15°C, the value of final viscosity and total setback was higher than that from the field. In wheat starch from Tanikei A6599‐4 (waxy mutant with stable hot paste viscosity), the peak viscosity temperature was higher and time maintained >80% of the peak was shorter at 15°C than that from the field. Genetic analysis using doubled‐haploid (DH) lines from a combination of Tanikei A6599‐4 and Kanto 118 (low‐amylose line) showed that apparent amylose content increased and the starch pasting curve and properties changed in waxy progenies similar to Tanikei A6599‐4.