Waxy Wheat Starch Research Articles

Physicochemical and Functional Properties of Tetraploid and Hexaploid Waxy Wheat Starch

AbstractWaxy wheats possess unique starch functional properties that may be useful in specific end‐uses. To assess the physicochemical, thermal, and pasting properties, starches from seven waxy genotypes originating from two wheat classes, tetraploid durum and hexaploid hard red spring (HRS), were evaluated and compared with their counterpart non‐waxy wild types. The amylose content ranged from 2.3% to 2.6% in waxy durum lines, compared to 29.2% in normal durum control, and 2.1% to 2.4% in waxy HRS, compared with 26.0% in normal HRS control. Significant differences in the degree of crystallinity were observed between the waxy and control starches, despite similar A‐type X‐ray patterns, although differences between the two wheat classes were non‐significant. Both, control and waxy starches displayed an X‐ray peak corresponding to the amylose‐lipid complex, but the intensity of the peak was markedly lower in the waxy starches. The waxy durum starches exhibited the highest transition temperatures as measured by Differential Scanning Calorimetry (DSC), whereas, the enthalpy of gelatinization of most waxy genotypes was statistically higher than that of the controls. All waxy starches displayed high peak viscosity, high breakdown, and low setback profile as measured by the Rapid Visco Analyser (RVA). Texture analysis of RVA gels revealed significant differences between waxy and non‐waxy wheats, as well as between waxy tetraploid and hexaploid wheats, confirming that the nature and class of wheat starch would play a significant role when using waxy wheat blends in different wheat‐based products.

Role of Amylose in the Maintenance of the Configuration of Rice Starch Granules

AbstractAmylose contents in 39 strains of rice starch, including waxy starch, low amylose containing starch, and non‐waxy starch, were measured. Seguchi et al. [1] reported that waxy wheat starch exhibits a ghost appearance by staining and swelling with 25% KI/10%I2 solution at 25 °C. We subjected the 39 rice strains to staining in the same manner. We found that the relative ghost area (%) in a rice starch, which is a measure of granule swelling in 25%KI/10%I2 solution, , is related to its amylose content (r = ‐0.78). As the relative ghost area (%) of the rice starch increased rapidly when the amylose content decreased below 5%, we concluded that at least 5% of amylose is required to maintain the structure of rice starch granules. Furthermore, the red‐brown central region in ghostly appearing granules decreases with amylose level and the surrounding light brown region increases. When the starch does not contain amylose, the ghost is entirely light brown. The decrease in the area of the red‐brown central region with decreasing amylose content suggests that amylose is concentrated in the red‐brown central region of the ghost.

Composition and Reactivity of A‐ and B‐type Starch Granules of Normal, Partial Waxy, and Waxy Wheat

ABSTRACTWheat has great potential to make inroads into starch markets with the advent of partial waxy and waxy starches of diverse composition and properties. The majority of isolated starch utilized in food applications is chemically modified to improve starch properties according to the intended use. Therefore, it is critical to understand factors that affect wheat starch reactivity. This work investigated the relative reactivities of normal, partial waxy, and waxy wheat starches and their respective A‐ and B‐type starch granule fractions. Native starch isolated from four closely related soft wheat lines (normal, partial waxy, and full waxy) was modified through 1) substitution (propylene oxide analog) and 2) cross‐linking (phosphorus oxychloride) reactions to generate both types of modified starch products for each wheat line. Characterization of the unmodified starch fractions confirmed compositional differences among the cultivars and their respective granule types. In cross‐linking reactions, B‐type granules were slightly more reacted than A‐type granules for all cultivars, while the waxy starch generally exhibited higher reactivity compared with normal and partial waxy starches. For the substituted starches, no differences in reactivity were observed among the cultivars or between the two granule types.

Effects of Starch Amylose Content of Wheat on Textural Properties of White Salted Noodles

ABSTRACTWhite salted noodles were prepared through reconstitution of fractionated flour components with blends of waxy and regular wheat starches to determine the effects of amylose content on textural properties of white salted noodles without interference of protein variation. As the proportion of waxy wheat starch increased from 0 to 52% in starch blends, there were increases in peak viscosity from 210 to 640 BU and decreases in peak temperature from 95.5 to 70.0°C. Water retention capacity of waxy wheat starches (80–81%) was much higher than that of regular wheat starch (55–62%). As the waxy wheat starch ratio increased in the starch blends, there were consistent decreases in hardness of cooked noodles prepared from reconstituted flours, no changes in springiness and increases in cohesiveness. White salted noodles produced from blends of regular and waxy wheat flours became softer as the proportion of waxy wheat flour increased, even when protein content of flour blends increased. Amylose content of starch correlated positively with hardness and negatively with cohesiveness of cooked white salted noodles. Protein content of flour blends correlated negatively with hardness of cooked noodles, which were prepared from blends of regular (10.5% protein) and waxy wheat flours (> 16.4% protein).

Cross‐Linked Resistant Starch: Preparation and Properties

ABSTRACTResistant starches (RS) were prepared by phosphorylation of wheat, waxy wheat, corn, waxy corn, high‐amylose corn, oat, rice, tapioca, mung bean, banana, and potato starches in aqueous slurry (≈33% starch solids, w/w) with 1–19% (starch basis) of a 99:1 (w/w) mixture of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) at pH 10.5–12.3 and 25–70°C for 0.5–24 hr with sodium sulfate or sodium chloride at 0–20% (starch basis). The RS4 products contain ≤100% dietary fiber when assayed with the total dietary fiber method of the Association of Official Analytical Chemists (AOAC). In vitro digestion of four RS4 wheat starches showed they contained 13–22% slowly digestible starch (SDS) and 36–66% RS. However after gelatinization, RS levels fell by 7–25% of ungelatinized levels, while SDS levels remained nearly the same. The cross‐linked RS4 starches were distinguished from native starches by elevated phosphorus levels, low swelling powers (≈3g/g) at 95°C, insolubilities (<1%) in 1M potassium hydroxide or 95% dimethyl sulfoxide, and increased temperatures and decreased enthalpies of gelatinization measured by differential scanning calorimetry.

Physicochemical and Structural Characteristics of Flours and Starches from Waxy and Nonwaxy Wheats

ABSTRACTA waxy spring wheat (Triticum aestivum L.) genotype was fractionated into flour and starch by roller and wet‐milling, respectively. The resultant flour and starch were evaluated for end‐use properties and compared with their counterparts from hard and soft wheats and with commercial waxy and nonwaxy corn (Zea mays L.) starches. The waxy wheat flour had exceptionally high levels of water absorption and peak viscosity compared with hard or soft wheat flour. The flour formed an intermediate‐strength dough that developed rapidly and was relatively susceptible to mixing. Analysis by differential scanning calorimetry and X‐ray diffractometry showed waxy wheat starch had higher gelatinization temperatures, a greater degree of crystallization, and an absence of an amylose‐lipid complex compared with nonwaxy wheat. Waxy wheat and corn starches showed greater refrigeration and freeze‐thaw stabilities than did nonwaxy starches as demonstrated by syneresis tests. They were also similar in pasting properties, but waxy wheat starch required lower temperature and enthalpy to gelatinize. The results show analogies between waxy wheat and waxy corn starches, but waxy wheat flour was distinct from hard or soft wheat flour in pasting and mixing properties.

Structural and physical characteristics of waxy and other wheat starches

Structures and properties of starches isolated from waxy wheat, amylose-reduced wheat (Kanto 107), and normal hard red winter wheat (Centura and a commercial product) grains were examined. Apparent amylose contents of the four starches were <0.2, 21.5, 26.2, and 26.6%, respectively. Waxy wheat amylopectin (AP) had the largest molecular weight ( M w) and no detectable extra-long branch-chains. The M w of the AP displayed a negative correlation with the amylose content of the wheat starch, whereas the proportion of extra-long branch-chains of AP displayed a positive correlation with amylose content. Relationships between the M w and gyration radius ( R z ) suggested that the structure of waxy AP was more compact than that of other wheat APs. Branch chain-length distributions of AP analyzed by high-performance anion-exchange chromatography (HPAEC) showed that the peak chain-lengths of all the wheat starches were at DP12, and average chain-lengths varied between DP23.5 and 24.9. Centura AP had the highest proportion of long branch-chains (DP≥25). Onset gelatinization temperatures of waxy wheat, Kanto107, Centura, and commercial wheat starches were 55.7, 57.5, 55.6, and 54.9°C, respectively, and enthalpy changes were 13.6, 11.8, 10.7, and 10.6 J/g, respectively. Differences in pasting temperature and peak viscosity between waxy and normal wheat starches were substantially greater than the differences between maize starch counterparts.

Low- and Medium-DE Maltodextrins From Waxy Wheat Starch: Preparation and Properties

Low- and Medium-DE Maltodextrins From Waxy Wheat Starch: Preparation and Properties

Low- and Medium-DE Maltodextrins From Waxy Wheat Starch: Preparation and Properties

The goal of the research was to prepare maltodextrins (MD) from waxy wheat starch and waxy corn starch (control). Waxy wheat starches with 0.2% protein, 0.2% lipid and ∼1% amylose were isolated from two flours by mixing a dough, dispersing the dough in excess water, and separating the starch and gluten from the resultant dispersion. The mean recoveries were 72% for the starches and 76% for the gluten fraction with 80% protein. Maltodextrins having low-dextrose equivalence (DE) 1—2 and mid-DE 9—10 were prepared by treatment of 15% slurries of waxy wheat starch and waxy corn starch at 95 °C for 5—10 min and 20—50 min, respectively, with a heat-stable α-amylase. Denaturing the enzyme and spray-drying produced MD's with bulk densities of 0.3 g/cm 3. The powdery MD's were subjected to an accelerated-rancidity development test at 60 °C, and an off-odor was detected after 2 days storage for the low-DE MD's from the two waxy wheat starches (WxWS1-MD 1.2 and WxWS2-MD 1.5), but not for the low-DE waxy corn maltodextrin (WxCS-MD 2.2) or a commercial waxy corn MD with DE 1. None of the mid-DE 9—10 MD's developed off-odor after 30 days storage at 60 °C. The experimental products WxWS1-MD 9.2, WxWS2-MD 9.9 and WxCS-MD 9.1 showed high water-solubility and gave 1—10% aqueous solutions of high clarity with no clouding upon cooling.

Influence of Amylose Content on Properties of Wheat Starch and Breadmaking Quality of Starch and Gluten Blends

ABSTRACTThe effects of amylose content on thermal properties of starches, dough rheology, and bread staling were investigated using starch of waxy and regular wheat genotypes. As the amylose content of starch blends decreased from 24 to 0%, the gelatinization enthalpy increased from 10.5 to 15.3 J/g and retrogradation enthalpy after 96 hr of storage at 4°C decreased from 2.2 to 0 J/g. Mixograph water absorption of starch and gluten blends increased as the amylose content decreased. Generally, lower rheofermentometer dough height, higher gas production, and a lower gas retention coefficient were observed in starch and gluten blends with 12 or 18% amylose content compared with the regular starch and gluten blend. Bread baked from starch and gluten blends exhibited a more porous crumb structure with increased loaf volume as amylose content in the starch decreased. Bread from starch and gluten blends with amylose content of 19.2–21.6% exhibited similar crumb structure to that of bread with regular wheat starch which contained 24% amylose. Crumb moisture content was similar at 5 hr after baking but higher in bread with waxy starch than in bread without waxy starch after seven days of storage at 4°C. Bread with 10% waxy wheat starch exhibited lower crumb hardness values compared with bread without waxy wheat starch. Higher retrogradation enthalpy values were observed in breads containing waxy wheat starch (4.56 J/g at 18% amylose and 5.43 J/g at 12% amylose) compared with breads containing regular wheat starch (3.82 J/g at 24% amylose).

Development of the Waxy Wheat Starch Granule in the Endosperm, and Difference of Internal Structure between Wheat Waxy Starch and Other Waxy Cereal Starches

Waxy wheat lines were cultivated. The surface of the grains at 6 days after anthesis was wrinkled, and the diameter of the starch granules in the endosperm was rather small, however, afterwards the grains became smooth and the diameter of the starch granules in the endosperm was increased until 37 days after anthesis. Staining of the developing starch granules with a solution of 1.5 M KI and 0.4 M I2 showed that the granules of all starches changed to a ghost-like appearance, which consisted of two parts with different colors; a red-brown central part and a slightly pinkish surrounding part. However, the area of the slightly pinkish surrounding part in the whole ghost-like granule was small in the endosperm of wrinkled grains and gradually increased after the surface of the grain became smooth. Waxy barley, rice, maize, proso millet and foxtail millet starch also changed to ghost-like structure in a solution of 1.5 M KI and 0.4 M I2 , showing the internal structure of each granules. However, the ghost-like granules of these waxy starches showed only a simple single structure.

Study of Internal Structure of Waxy Wheat Starch Granules by KI/I2 Solution

ABSTRACTWheat starch granules were separated from waxy wheat flour by the acetic acid (pH 3.5) fractionation technique. Waxy wheat starch samples were stained red‐brown using KI/I2 solution. Subsequently, the concentration of the KI/I2 solution was increased to &gt;2.5% KI and 1.0% I2. Then the appearance of the waxy wheat starch granules quickly became ghostlike. The internal structure of the ghost could be observed. This structure consisted of two parts with different colors: a red‐brown central part and a slightly pinkish surrounding part. Sonication of the ghost at 20 kHz for 20 sec separated the central part from the surrounding part. Each of the separated parts were subjected to gel‐filtration chromatography, and their chromatography profiles indicated only amylopectin and no amylose. The central and surrounding parts had molecular weights of 54.3 × 105 and 23.8 × 106 from Berry plots, respectively.

Modified Waxy Wheat Starch Compared to Modified Waxy Corn Starch

Waxy wheat starch (WWS) and waxy corn starch (WCS) were cross-linked in an aqueous slurry at c. 37% starch solids with 0·013 to 0·050% phosphoryl chloride (starch basis) at pH 11·5 for 60 min in the presence of c. 2·1% sodium sulphate (starch basis). Increasing levels of phosphoryl chloride caused a steady decline in the final paste consistency of cross-linked WWS, but that of WCS proceeded through an optimum. Starch paste consistency was the resistance to stirring measured in a pasting instrument. WWS cross-linked at a low level gave a higher final paste consistency compared with cross-linked WCS. WWS and WCS were hydroxypropylated (HP) to low (c. 2·0%) and medium (c. 4·0%) levels by reaction with propylene oxide at pH 11·5 and 45 °C, and the HP starches were then cross-linked with 0·008 to 0·018% phosphoryl chloride. Again, cross-linked HP-WWS gave pasting curves with higher consistency at 6·25% starch solids compared with HP-WCS. WWS and its modified forms yielded pastes of lower clarity than those from WCS, but the pastes from HP/cross-linked WWS had better freeze-thaw stability. Cross-linking with phosphoryl chloride (0·025%) followed by acetylation with acetic anhydride (8·0%) yielded modified waxy wheat and waxy corn starches with similar paste consistencies, but a force-distance instrument indicated that the modified WCS was significantly stringier than the modified WWS.

Changes in Starch Granules Trapped and Heated Using Optical Tweezers

A microscopic method to investigate the swelling process of individual starch granules heated in excess water is proposed. A starch granule focused under a light microscope is adjustably trapped using the optical tweezing of a near-infrared laser beam, which simultaneously heats the granule. Using this method, morphological changes in starch granules during heating were continuously recorded and quantitatively analyzed by image-processing techniques. The changes in granules of domestic wheat starches with differing amylose content were investigated under irradiation by the laser beam at constant optical power. The shapes of swollen granules of waxy wheat starches were observed to be distinctly different from those of non-waxy starches. Numerical indicators, specifically the time constant of swelling for the granule and its swelling magnification, were also obtained. These showed little relation to the pasting profiles of the same starches, obtained with a Rapid Visco Analyser.

Thermal and Crystalline Properties of Waxy Wheat (Triticum aestivumL.) Starch

The physico-chemical properties of starch granules derived from waxy wheat were examined using spectrophotometry of their starch-iodine complexes, differential scanning calorimetry (DSC) and X-ray diffraction. DSC data showed a strong correlation between peak temperature and the enthalpy change for starch gelatinization for all samples; likewise, X-ray diffraction data also correlated with these gelatinization parameters. On the other hand there were no differences in the mean value of the diameter of starch granules between samples. It was concluded that the thermal properties of waxy wheat starch are adequately explained by its crystallinity.

Amylose and Lipid Contents, Amylopectin Structure, and Gelatinisation Properties of Waxy Wheat (Triticum aestivum) Starch

Abstract Starch was isolated from the endosperm of three recently developed waxy wheat lines and their parents. Their amylose and lipid contents, amylopectin structures and gelatinisation properties were evaluated. The endosperm starch from waxy wheat lines is composed essentially of amylopectin. The apparent amylose (1·2–2·0 g/100 g) and lipid contents (0·12–0·29 g/100 g) are much lower than the apparent amylose (26·0–28·4 g/100 g) and lipid contents (1·05–1·17 g/100 g) of their non-waxy parents. The amylopectin of waxy wheat lines is structurally identical to that of the parents. The peak gelatinisation temperature and gelatinisation enthalpy for waxy starch are significantly higher than for non-waxy starch, but the gelatinisation enthalpy for the amylopectin fraction of waxy starch is nearly identical to that of non-waxy starch.