Prime Starch Research Articles

Flour from wheat cultivars of varying hardness produces semi-sweet biscuits with varying textural and structural properties

Semi-sweet biscuits were prepared from flour from wheat cultivars with Single Kernel Characterization System hardness values ranging from 22 to 92. The impact of flour protein level on biscuit properties was compensated for by diluting flour samples of higher protein level with their isolated prime starch fraction. Biscuits prepared from hard wheat flour showed higher fracture stress than their soft wheat flour counterparts. Softer texture mainly resulted from higher porosity, resulting from larger pores. Furthermore, biscuit matrix strength also contributed to biscuit texture. Biscuit texture is strongly affected by wheat hardness and results from the interplay between different hardness-associated flour properties (damaged starch, protein quality, …) as well as from their effect on both biscuit structure and matrix properties.

Starch isolation method impacts soft wheat (Triticum aestivum L. cv. Claire) starch puroindoline and lipid levels as well as its functional properties

Wheat (Triticum aestivum L.) kernel hardness is a major quality characteristic, which has been ascribed to the presence of puroindolines a and b. These proteins occur in higher levels at the surface of water-washed starch granules from soft wheat cultivars than at that of starch from hard wheat cultivars. In the present study, prime starch was isolated from flour from soft wheat (cultivar Claire) using a dough ball or batter based separation method. Starch isolated with the dough ball method contained lower levels of puroindolines, as well as of other starch granule associated proteins and lipids than that isolated with the batter method. Similar patterns of puroindoline and lipid levels after starch isolation can presumably be related to (polar) lipid binding by puroindolines. Both isolated starch fractions showed comparable differential scanning calorimetry thermograms, whereas higher levels of starch surface associated components restricted starch swelling. Necessary controls demonstrated that the observed differences did not arise from artefacts associated with hydration, fractionation or freeze-drying in the experimental protocols. Apparently, proteins and lipids at the starch granule surface impact water absorption and, as such, starch swelling, but they do not affect starch granule internal phenomena such as melting of the crystalline amylopectin chains.

The tryptophan-rich domain of puroindoline is directly associated with the starch granule surface as judged by tryptic shaving and mass spectrometry

The starch granule surface is a frontline of microbial attack and defence, operating in the background of normal starch granule metabolism. Puroindoline, a wheat protein which binds starch granule surfaces, contains a unique tryptophan-rich domain likely responsible for this property, though direct evidence is lacking. To test puroindoline’s tight association, prime starch granule extracts were water-washed 8 or 20 times and residual puroindoline removed using a solution of 50% isopropanol/50 mM NaCl. We found that this solvent was consistent in the amount of protein extracted from wheat flour and washed starch, regardless of initial protein content. Relative quantification of puroindoline following water-washing was performed using dot blot. Washing more than 8 times did not further reduce puroindoline content of starch granules suggesting a strong association with the starch granule surface. To identify the tryptophan-rich domain tightly associated with the starch granule surface, a combination of in situ tryptic digestion and mass spectrometry was used. Following digestion and water-washing, 50% isopropanol/50 mM NaCl was used to remove tightly-associated peptides for identification by mass spectrometry. Using this method, we identified the tryptophan-rich domain of puroindoline directly bound to the starch granule surface of wheat.

Investigation of Dry‐Heated Hard and Soft Wheat Flour

AbstractThe Amylograph profile of dry‐heated (120°C, 120 min) wheat flour showed a drastic change, i.e. an earlier onset time and higher peak viscosity than that of a control. However, no difference in the size of the starch granules was observed between dry‐heated and normal starch at every temperature. Wheat flour was fractionated with acetic acid, and the separated prime starch (PS) and tailings (T) fractions were dry‐heated at 120°C for 30, 60, 90, and 120 min, respectively. There was almost no difference in the RVA and DSC profiles between PS and dry‐heated PS, and T and dry‐heated T fractions, i.e., dry heating of wheat flour did not change the structures of starch that would be related to onset time and peak viscosity in the Amylograph profile. We thus excluded the water solubles (WS) fractions from control and dry‐heated wheat flour, but the effect of dry heating on the Amylograph profile was not lost. Next, the gluten (G) fraction was excluded following WS fraction from these wheat flours, and Amylograph tests were performed. The Amylograph profiles in both wheat flours were almost coincidental, which showed that the G fraction in dry‐heated wheat flour caused the earlier onset time and higher peak viscosity.

Effect of Dry‐Heated Prime Starch and Tailings Fractions in Wheat Flour on Pancake Springiness

Because chlorination is prohibited in Japan for health and safety concerns, a safer improvement method for wheat flour is desired and dry-heating of wheat flour improves the pancake springiness as an alternative to chlorination (Seguchi 1990, 1993; Seguchi et al 1998; Ozawa and Seguchi 2006). Sollars (1958) and Donelson and Wilson (1960), by means of reconstitution technique, investigated the effect of chlorine bleaching on flour fractions in cakes and cookies. Russo and Doe (1970), Thomasson et al (1995), and Fustier and Gelinas (1998) reported that heat treatment of unchlorinated cake flour improved its cake-baking properties. Heating of wheat at 60-100°C is detrimental to loaf volume (Hutchinson and Booth 1946; Becker and Sallans 1956; McDermott 1971; Hook 1980; Every 1987). Hydrophobicity of the surface of prime starch granules in the dry-heated wheat flour was observed (Seguchi 1984), similar to that in chlorinated wheat flour (Seguchi and Matsuki 1977a). Seguchi (1984, 1993) reported that the improvements of pancakes were caused by lipophilic change of starch granule surface protein by dry-heating of wheat flour. Ozawa and Seguchi (2006) showed hydrophobicity in dry-heated wheat flour, fractionated the dry-heated wheat flour to water solubles, gluten, prime starch, and tailings fractions and indicated the interaction between prime starch and tailings fractions. Nakamura et al (in press) reported that dry-heated wheat flour could increase the volume of Kasutera cake (Japanese sponge cake) due to the hydrophobic nature of dry-heated wheat flour. However, as yet there was no direct evidence that dry-heated prime starch and tailings fractions were related to the springiness of pancake from the pancake baking test with reconstituted wheat flour, which was composed of dry-heated and unheated fractions. In this experiment, we used specific heating conditions (120°C for 120 min) for wheat flour because Ozawa and Seguchi (2006) found that drying for longer periods was not essential to pancake springiness. We fractionated wheat flour to water solubles, gluten, prime starch, and tailings fractions, and examined whether dry-heated prime starch and tailings fractions in reconstituted wheat flour contributed to the improvement of pancake springiness.

In vitro starch digestibility and estimated glycemic index of chemically modified corn starches

Abstract Normal corn starch was chemically modified by oxidation, acetylation, hydroxypropylation, and cross-linking, and the digestibility and glycemic indices (GI) of these modified starches were examined by in vitro hydrolysis using pancreatic α-amylase. During the early stage of hydrolysis (up to 60 min) with prime (ungelatinized) starches, the modified starches were hydrolyzed at greater extents than the unmodified starches. However, at the late stage of hydrolysis (after 3 h), the modified starches showed lower degrees of hydrolysis than the unmodified starch. The amount of resistant starch (RS) in prime starches were 23.4%, 35.1%, 34.2%, and 13.9% in the acetylated, oxidized, hydroxypropylated, and cross-linked starches, respectively, whereas the unmodified starch contained 11.9%. The amount of slowly digestible starch (SDS) was decreased as the RS content was increased by the modification, indicating that some of the SDS transformed to RS. By gelatinization, all the starches, regardless of type of modification, were more quickly hydrolyzed and reached maximum levels within 20 min. Like the prime starches, the modified starches contained higher contents of undigested starches after gelatinization. The modifications except cross-linking reduced rapidly digestible starch (RDS) content but increased the RS content when the starches were gelatinized. The hydroxypropylated starch had the lowest GI values, which were estimated from the hydrolysis profiles (70.6 and 86.2 in prime and gelatinized states, respectively), whereas the GI values of cross-linked starch were similar to those of the unmodified starch. Therefore, chemical substitution such as hydroxypropylation and acetylation, and oxidation can be used to reduce the starch digestibility and raise the RS content.

Impact of endogenous constituents from different flour milling streams on dough rheology and semi-sweet biscuit making potential by partial substitution of a commercial soft wheat flour

A flour fractionation-reconstitution procedure was used to study the substitution of a commercial soft wheat flour with gluten, water extractables, prime starch and starch tailing fractions isolated from patent and clear flour streams on dough rheology and semi-sweet biscuit characteristics. Substitution of soft wheat flour with increasing levels of the native patent and clear flour streams raised the dough consistency, hardness and elastic properties as well as the biscuit textural attributes (density, hardness). The dough stickiness of the base flour was also reduced and the biscuits were free of cracks. Gluten isolated from the patent flour had a greater impact on dough consistency, hardness and elastic properties than gluten obtained from the clear flour, likely due to the superior protein quality of the former. Additionally, with increasing gluten levels in the fortified flour there were moderate increases in biscuit density, hardness, and lower crunchiness. The addition of starch tailings produced the largest impact on consistency and hardness of the dough. This fraction also exerted a pronounced effect on biscuit density and hardness, while it lowered crunchiness, presumably due to its higher pentosan content. Overall, the dough rheological properties and biscuit characteristics were controlled by the amount-nature of the fractions added; i.e., besides gluten (amount and quality), other constituents such as pentosans and the overall composition of the flour blends can largely affect the quality of the semi-sweet biscuits.

Assessment of selected cooking characteristics of prime starch and food grade fibre isolated from cassava ( Manihot esculenta ) pulp

Ease of separation of dietary fibre components of cassava pulp relative to other tropical root crops was the motivation for this study. Food grade fibres were isolated from cassava pulp using simple technique that consist essentially solvent mixture-separation procedure. Assessment of selected cooking proprieties namely paste formation and swelling capacity of the fibre isolates in comparison to the prime starch showed that isolated fibres exhibited variable cooking properties that are collectively independent of fibre size as determined by sieve mesh clearance, contrast to the cooking property of the prime starch. The fibres may find usefulness as carbohydrate food ingredients.

Improving Effects of Stored Wheat Flour on Pancake Texture

Various protein containing soft wheat flours were stored at room temperature (15-25°C ) for 12 months. Pancakes baked using these flours yielded higher pancake springiness when tested. The wheat flours were fractionated to water solubles, gluten, prime starch and tailings fractions by an acetic acid fractionation technique. A gradual increase in the interaction between prime starch and tailings fractions was observed after inclusion of these fractions in each flour. However, the stored time for complete interaction varied in relation to flour protein content. It was found that the increase of pancake springiness was strongly associated with the interaction between prime starch and tailings fractions in stored wheat flour. Mixograph profiles showed a gradual increase in the hydrophobicity of wheat flour with increased storage. Rapid Visco Analyser (RVA) profiles of these flours indicated that the maximum viscosity increased and pasting temperature decreased; these effects were probably attributable to the hydrophobic interaction of flour fractions.

Effect of Flour Changes Due to Storage on Kasutera Cake Volume

Four kinds of soft wheat flours, Takaragasa gold, Furian, Tokutakaragasa and Aokoma (protein 9.06, 9.30, 9.69 and 10.17%, respectively), which were commercially used for sugar- and protein-rich Kasutera cake, were stored at room temperature (15-25°C ) for 2, 4, 6, 8, 10 and 12 months. A Kasutera cake baking test with these stored wheat flours showed that the volume (cm3) of Kasutera cake was gradually increased with elapse of storage period. These wheat flours were fractionated into water solubles, gluten, prime starch (A starch granule) and tailings (mixture of water insoluble proteins, polysaccharides, lipids and B starch granule) fractions using an acetic acid fractionation technique. A gradual increase of the interaction between prime starch and tailings fractions could be observed from the inclusion of the prime starch to the tailings fractions in each wheat flour with storage. It was found that the increase of volume of the Kasutera cake was highly related to the interaction between the prime starch and tailings fractions in the stored wheat flours. Mixograph profiles showed that the hydrophobicity of the wheat flour depended on the storage period. RVA (Rapid Visco Analyser) profiles of these stored wheat flours showed that the onset time became earlier and the peak viscosity increased, likely due to the hydrophobic interaction of flour components.

In situ examination of starch granule-soy protein and wheat protein interactions

The objective of this study was to evaluate the association between heat and pressure-treated soy proteins and wheat prime starch relative to the level of granule surface proteins present. Soy isolates were manufactured from defatted soy flour and from two types of textured soy flour. Conditions for binding between wheat starch and soy fractions were established by altering pH, protein and sucrose concentrations. Conformations of exogenous proteins bound to the wheat starch granule surface were evaluated using an amyloglucosidase assay. Proteins present on the granule surface were removed and soy protein binding was reevaluated. Thermal and pressure processing of soy protein significantly influenced binding kinetics. Textured soy proteins exhibited increased wheat starch granule adsorption characteristics compared to untreated soy protein. Removal of native wheat starch granule surface proteins decreased the binding of added proteins. This suggests that native granule proteins may mediate the binding of exogenous protein.

Relationship between Pancake Springiness and Interaction of Wheat Flour Components Caused by Dry Heating

Dry heated wheat flours were fractionated into water-soluble, gluten, prime-starch and tailings fractions by an acetic acid fractionation technique. With a gradual increase in the duration time at each temperature, recovery of the prime-starch fraction decreased while the tailings fraction increased. However, the water-soluble and gluten fractions did not change, which is indicated by the fact that interaction between the prime-starch and the tailings fractions occurred for these treatments. A mixograph profile showed hydrophobicity of the wheat flour by dry heating. These dry heated wheat flours gave a large pancake springiness. The temperatures and the duration times for complete pancake springiness were as follows ; at 60°C for 540h (22.5 days) ; 70°C for 144h (6 days) ; 80°C for 72h (3 days) ; 90°C for 24h (1 day) ; 100°C for 6h ; 110°C for 4h ; 120°C for 2h. Interaction between the prime starch and the tailings fractions in wheat flour produced by dry heating was highly correlated to improvements in the pancake springiness.

Wet-milling properties of waxy wheat flours by two laboratory methods

Straight-grade flours roller-milled from seven waxy and two control (nonwaxy and partial waxy) wheats ( Triticum aestivum) were wet-milled by dough-washing (DW) and dough-dispersion and centrifugation (DD&C) methods to give starch, gluten, tailings, and water-solubles fractions. Compared to the controls, flour yields of the waxy wheats were lower. The waxy flours contained more crude fat and pentosans and less total starch. Gluten proteins of the waxy flours appeared to be weaker. By the DW method, both of the controls but only two of the seven waxy flours could be wet-milled. The remaining five waxy flours failed in the DW method as their doughs lost cohesiveness and elasticity during kneading and washing under water. Those waxy flours were instead wet-milled by the modified DW method, where the doughs were gently hand-rubbed on a 125-μm opening screen to facilitate the passage of the starch and water-solubles through while retaining the gluten agglomerates on the screen. The prime starch and tailings of the waxy flours were not separated as visibly as those of the controls during their centrifugal purification, which in turn led to a reduction in yields and purities of their prime starch and gluten fractions. On the other hand, the wet-milling characteristics of the waxy flours by the DD&C method were comparable to those of the controls because the DD&C method is apparently less dependent than the DW method on the gluten aggregation traits of flours.

Size Distribution and Properties of Wheat Starch Granules in Relation to Crumb Grain Score of Pup‐Loaf Bread

ABSTRACTTwelve hard winter wheat flours with protein contents of 11.8–13.6% (14% mb) were selected to investigate starch properties associated with the crumb grain score of experimentally baked pup‐loaf bread. The 12 flours were classified in four groups depending on the crumb grain scores, which ranged from 1 (questionable‐unsatisfactory) to 4 (satisfactory). Flours in groups 1, 2, 3, and 4 produced breads with pup‐loaf volumes of 910–1,035, 1,000–1,005, 950–1,025, and 955–1,010 cm3, respectively. Starches were isolated by a dough handwashing method and purified by washing to give 75–79% combined yield (dry flour basis) of prime (62–71%) and tailing (7–16%) starches. The prime starch was fractionated further into large A‐granules and small B‐granules by repeated sedimentation in aqueous slurry. All starches were assayed for weight percentage of B‐granules, swelling power (92.5°C), amylose content, and granular size distribution by quantitative digital image analysis. A positive linear correlation was found between the crumb grain scores and the A‐granule sizes (r = 0.65, P < 0.05), and a polynomial relationship (R2 = 0.45, P < 0.05) occurred between the score and the weight percentage of B‐granule starch. The best crumb grain score was obtained when a flour had a weight percentage of B‐granules of 19.8–22.5%, shown by varietal effects.

Effects of Secondary Structures of Heated Egg White Protein on the Binding Between Prime Starch and Tailings Fractions in Fresh Wheat Flour

ABSTRACTDried egg white protein was heated at 120°C for 1 hr, added to a fresh wheat flour (protein 8.6%), and the protein and wheat flour were subjected to acetic acid (pH 3.5) fractionation. The results showed that egg white protein increased the binding between prime starch (PS) and tailings (T) fractions in wheat flour. Several conditions for heating of egg white protein were examined to determine 1) the effect of the amount of water added to the protein before heating; 2) the effect of heating time (hr) on protein at 120°C; and 3) the effect of heating temperature on the binding between PS and T fractions. The amount of protein per 50.0 g of wheat flour was further examined for the maximum binding between PS and T fractions. The heated egg white protein was analyzed by Fourier transform infrared (FT‐IR) spectroscopy, and the changes in the secondary structures (α‐helix, β‐sheets, and others) of the protein caused by heating were studied. When egg white protein was heated at 120°C for 8 hr, 9.0% of the α‐helix structures of egg white protein decreased to 3.0%, and 37.0% of the β‐sheet structures increased to 41.0%. The decrease of α‐helix and increase of β‐sheet structures of heated egg white protein were related to the increase in the binding between PS and T fractions in the same heated egg white protein and wheat flour sample. A relationship between the structural changes in heated egg white protein (180°C, 1 hr) and the binding between PS and T fractions in the heated egg white protein and wheat flour was also observed.

Starch graft poly(methyl acrylate) loose-fill foam: preparation, properties and degradation.

Starch graft poly(methyl acrylate) (S-g-PMA) was prepared by ceric ion initiation of methyl acrylate in an aqueous corn starch slurry (prime starch) which maximized the accessibility of the starch for graft polymerization. A new ceric ion reaction sequence was established as starch-initiator-methyl acrylate followed by addition of a small amount of ceric ion solution when the graft polymerization was almost complete to quench the reaction. As a result of this improved procedure, no unreacted methyl acrylate monomer remained, and thus, essentially no ungrafted poly(methyl acrylate) homopolymer was formed in the final grafted product. Quantities of the high purity S-g-PMA so prepared in pilot scale were converted to resin pellets and loose-fill foam by single screw and twin screw extrusion. The use of prime starch significantly improved the physical properties of the final loose-fill foam, in comparison to foam produced from regular dry corn starch. The S-g-PMA loose-fill foam had compressive strength and resiliency comparable to expanded polystyrene but higher bulk density. The S-g-PMA loose-fill foam also had better moisture and water resistance than other competitive starch-based materials. Studies indicated that the starch portion in S-g-PMA loose-fill foam biodegraded rapidly, whereas poly(methyl acrylate) remained relatively stable under natural environmental conditions.

Characteristics of Noodles and Bread Prepared from Double‐Null Partial Waxy Wheat

ABSTRACTDouble‐null partial waxy wheat (Triticum aestivum L.) flours were used for isolation of starch and preparation of white salted noodles and pan bread. Starch characteristics, textural properties of cooked noodles, and staling properties of bread during storage were determined and compared with those of wheat flours with regular amylose content. Starches isolated from double‐null partial waxy wheat flours contained 15.4–18.9% amylose and exhibited higher peak viscosity than starches of single‐null partial waxy and regular wheat flours, which contained 22.7–25.8% amylose. Despite higher protein content, double‐null partial waxy wheat flours, produced softer, more cohesive and less adhesive noodles than soft white wheat flours. With incorporation of partial waxy prime starches, noodles produced from reconstituted soft white wheat flours became softer, less adhesive, and more cohesive, indicating that partial waxy starches of low amylose content are responsible for the improvement of cooked white salted noodle texture. Partial waxy wheat flours with >15.1% protein produced bread of larger loaf volume and softer bread crumb even after storage than did the hard red spring wheat flour of 15.3% protein. Regardless of whether malt was used, bread baked from double‐null partial waxy wheat flours exhibited a slower firming rate during storage than bread baked from HRS wheat flour.

Isolation and Characterization of Cotyledon Fibers from Peas, Lentils, and Chickpeas

ABSTRACTMethods were developed to efficiently isolate legume cotyledon fibers with relatively high yields and purities. Seeds of pea (Pisum sativum), chickpea (Cicer arientinum), and lentil (Lens culinaris) were roller milled into flour and fractionated into prime starch, tailings starch, and water solubles. Insoluble dietary fiber was isolated from tailings starch by wet screening on sieves with openings ranging from 53 to 90 μm. Yield of insoluble fiber using a sieve with 53‐μm openings ranged from 49.7 to 59.2% of insoluble fiber in flour with purities ranging from 85.5 to 87.3%. Soluble dietary fiber was isolated from the water‐soluble fraction following acid precipitation of soluble protein at pH 4. Soluble fiber yield ranged from 83.3 to 89.6% of flour soluble fiber with purities ranging from 64.5 to 70.6%. Glucose was the most common sugar component of hulls and soluble cotyledon fibers, while arabinose was the main sugar in insoluble fibers. Insoluble fiber exhibited significantly higher swelling capacities and water and oil binding capacities in comparison to hulls and soluble cotyledon fibers. Apparent viscosities of soluble cotyledon fibers ranged from 3.13 to 3.43 Pa•sec and exhibited Newtonian characteristics.

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

AbstractTwo 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

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

AbstractThe 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