Granule Surface Proteins Research Articles

Unraveling the impact of starch granule-associated proteins on the emulsifying ability of quinoa starch granules at multiple scales

Total starch granule-associated proteins (tGAP), including granule-channel (GCP) and granule-surface proteins (GSP), alter the physicochemical properties of starches. Quinoa starch (QS) acts as an effective emulsifier in Pickering emulsion. However, the correlation between the tGAP and the emulsifying capacity of QS at different scales remains unclear. Herein, GCP and tGAP were selectively removed from QS, namely QS-C and QS-A. Results indicated that the loss of tGAP increased the water permeability and hydrophilicity of the starch particles. Mesoscopically, removing tGAP decreased the diffusion rate and interfacial viscous modulus. Particularly, GSP had a more profound impact on the interfacial modulus than GCP. Microscopically and macroscopically, the loss of tGAP endowed QS with weakened emulsifying ability in terms of emulsions with larger droplet size and diminished rheological properties. Collectively, this work demonstrated that tGAP played an important role in the structural and interfacial properties of QS molecules and the stability of QS-stabilized emulsions.

Insight into the promoted recrystallization and water distribution of bread by removing starch granule - surface and - associated proteins during storage

The influence of starch granule surface proteins (SGSPs) and starch granule-associated proteins (SGAPs) on bread retrogradation was investigated in a reconstituted dough system. The removal of both SGSPs and SGAPs resulted in poor bread qualities, decreasing specific volume and crumb porosity, leading to more baking loss and compact crumb structure. Particularly, removing SGSPs was effective in promoting the bread retrogradation. After 7 days of storage, the hardness of bread without SGSPs showed an increase of 353.34 g than the bread without SGAPs. Proton population and relaxation times exhibited that the absence of SGSPs significantly decreased the content of bound water from 11.51 % to 7.03 %, indicating lower water-holding capacity due to the loosen gelling structure. Compared to the control group, bread without SGSPs accelerated the starch recrystallinity by a reduction in soluble starch content, thereby increasing the retrogradation enthalpy and relative crystallinity through promoting the molecular reassociation in starch.

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.

PHYSICAL PROPERTIES OF SUGAR‐SNAP COOKIES USING GRANULE SURFACE DEPROTEINATED WHEAT STARCH

ABSTRACT The physical properties of soft wheat starch granule surface proteins and soy flours or isolates, which contribute to the texture of sugar‐snap cookies was studied. Soft wheat flour was deproteinated and cookies were produced containing 0, 10, 20 or 30% soy flour, or one of two types of ground, textured soy flour. Color, fracture force and spread ratio of cookies were determined. Cookies formulated with wheat starch stripped of the starch granule surface proteins exhibited significant alterations in diameter, fracture force, thickness and surface cracking. Cookies containing ground, textured soy flour and protein‐stripped starch granule wheat flour were larger, thinner and had more surface cracking than those produced with nontextured soy flour. Wheat starch granule surface proteins appear to partially mediate the interaction of proteins and starch in a sugar‐snap cookie system.

Presence and Amounts of Starch Granule Surface Proteins in Various Starches

Presence and Amounts of Starch Granule Surface Proteins in Various Starches

Model system analysis of wheat starch-soy protein interaction kinetics using polystyrene microspheres

The objective of this study was to identify the interaction of puroindoline and starch lipids with soy proteins when coupled to polystyrene microspheres. Manipulation and removal of wheat starch granule surface proteins and lipids may damage granule integrity and hinder studies of ungelatinized starch systems. Therefore, 5 μm polystyrene microspheres were used to evaluate the role of starch granule surface components on exogenous protein binding. Puroindoline, phospholipid, glycolipid and triglyceride were passively adsorbed to the surface of polystyrene microspheres. Binding assays using soy protein indicated that puroindoline-lipid coated microspheres adsorbed soy protein to a greater extent than did those coated with puroindoline alone. Phospholipids increased binding more than glycolipids and triglycerides.

Oil Binding Ability of Chlorinated and Heated Wheat Starch Granules and Their Use in Breadmaking and Pancake Baking

Chlorination and heat treatment of wheat flour changes the surface character of starch granules from hydrophilic to hydrophobic, and high oil binding ability of the starch granules can be observed. It was suggested that the hydrophobicity, in case of chlorination, was due to chemical modification of the starch granule surface proteins, and, in case of heat treatment, due to conformational changes of the proteins. This hydrophobicity could be also obtained by aging (233 days at room temperature). The hydrophobicity of starch granules in batter is highly related to the springiness of pancake. Heat treated wheat starch granules can encapsulate flavor through their oil binding ability.

Oil Binding Ability of Chlorinated and Heated Wheat Starch Granules and Their Use in Breadmaking and Pancake Baking

Chlorination and heat treatment of wheat flour changes the surface character of starch granules from hydrophilic to hydrophobic, and high oil binding ability of the starch granules can be observed. It was suggested that the hydrophobicity, in case of chlorination, was due to chemical modification of the starch granule surface proteins, and, in case of heat treatment, due to conformational changes of the proteins. This hydrophobicity could be also obtained by aging (233 days at room temperature). The hydrophobicity of starch granules in batter is highly related to the springiness of pancake. Heat treated wheat starch granules can encapsulate flavor through their oil binding ability.

The Surface Chemistry of Starch Granules Studied by Time-of-Flight Secondary Ion Mass Spectrometry

This paper reports the novel application of time-of-flight-secondary ion mass spectrometry (TOF-SIMS) to the investigation of starch granule surface chemistry and composition. TOF-SIMS spectra were recorded from five different starch samples, and were interpreted by applying standard mass spectrometry rules. The chemical identity of the majority of peaks in the spectra have thus been assigned, and allow the identification of ions arising from granule surface carbohydrates, lipids and surface contamination. The remaining peaks, which could not be assigned to the above species, have been tentatively assigned as arising from granule-surface proteins. The TOF-SIMS spectra reveal significant information regarding the types of lipids present at the starch granule surface and the identities of their acyl R chains. TOF-SIMS analysis of chlorinated starch samples lead to the conclusion that neither direct addition of chlorine to starch polymers, nor oxidation of the C2 and C3 hydroxyls to carbonyl groups, occurs following chlorination. The TOF-SIMS spectra reveal however, that the phosphocholine group of starch surface phospholipids is modified following chlorination, and furthermore, that chlorination may cause starch depolymerization.

薄力小麦粉のクロリネーションや加熱処理がばい焼時に澱粉性食品に及ぼす影響

Chlorination of wheat flour improved the pancake textures (higher springiness and lower gumminess) and increased the pancake volume. From results of the pancake baking tests with reconstituted wheat flours, the improvement of the pancake textures was dependent on chlorinated prime starch fraction, and the increase of pancake volume was dependent on the chlorinated gluten fraction. Microscopic observation showed that the nature of the chlorinated starch granule changed from hydrophilic to hydrophobic (lipophilic), which had relationship to the improvement of the pancake textures. Protease experiments of the chlorinated wheat starch granules and model experiments using protein-coated chlorinated glass powder that the hydrophobicity (lipophilization) was caused by the change of starch granule surface proteins. The pancake textures also showed the same improvement when wheat flour was heat-treated. Heated wheat starch granules also showed strong hydrophobicity (lipophilization), which is also caused by the change of starch granules surface proteins. These chlorinated and heated wheat starch granules have shown to bind to the tailings fraction in wheat flour and the same phenomenon was also observed in pancake crumb baked with this treated wheat flour. The binding of these fractions was caused by the hydrophobicity of the starch granules and rigid cake cell wall could be formed and showed good pancake textures (higher springiness and lower gumminess).

Proteins associated with the surface of wheat starch granules purified by centrifuging through caesium chloride

Purified starch was isolated by centrifuging crude starch washed from macerated whole wheat, or an aqueous flour-water suspension, through 80% (w/v) caesium chloride. Granule surface proteins were extracted with 2% sodium dodecylsulphate (SDS) at 20 °C and integral proteins were recovered by extracting with SDS at 50 °C. Integral proteins were qualitatively and quantitatively constant in the starches examined, and provided a convenient internal standard for electrophoresis when total (surface+integral) proteins were extracted together at 50 °C rather than consecutively. In typical starch samples total nitrogen content (35-40 mg N/100 g) was comprised of 3-10 mg N in surface proteins, 13-15 mg N in integral proteins and the 14-20 mg N in lysophospholipids. Electrophoresis on SDS-polyacrylamide gradient (10–20 %) gels showed that purification removed most surface proteins other than the 15 kDa protein friabilin, associated with soft endosperm texture, which was not readily desorbed by the caesium chloride. In starches from soft wheats the small B-granules had more friabilin than the large A-granules, roughly in proportion to their surface area. The method is suitable for screening small samples of wheat for friabilin on its starch and (by association) soft or hard endosperm texture.

Isolation and analysis of starch from single kernels of wheat and barley

A method for isolating granular starch from single kernels of wheat and barley is described. Whole kernels were degermed, cracked, steeped in water, then macerated to release crude starch which was purified in two stages. Centrifuging through 80% (w/v) caesium chloride removed all less dense cellular material, storage proteins and some starch granule surface proteins. For some purposes this starch was sufficiently pure, but normally all traces of surface proteins and lipids were removed by washing with 0·5 % sodium laurate. Starch preparations were washed several times with water, then acetone, and finally air-dried. Starch yields and properties using the single kernel (SK) method were similar to those of bulk starch prepared conventionally from 10–30 g grain. Granule dimensions of SK starch, measured by Coulter Counter, were slightly smaller but recoveries of small B-granules were frequently better. Gelatinization properties of SK starch, measured by differential scanning calorimetry, and carbohydrate composition were very similar to those of bulk starch, but lipid and protein contents were lower due to the more efficient removal of contaminants from the surface of the granules with caesium chloride and sodium laurate.