Author Contributions
J.W.: conceptualization, methodology, investigation, data curation, validation, formal analysis, writing—original draft, visualization, supervision. X.S.: methodology, investigation, data curation, validation, formal analysis. X.X.: methodology, resources. Q.S.: methodology, resources. M.L.: methodology, resources, project administration, funding acquisition, supervision. Y.W.: conceptualization, methodology, resources, formal analysis, writing—review and editing, visualization, supervision. F.X.: methodology, resources, formal analysis, visualization, writing—review and editing. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Light microscopy images (at a magnification of 20×) of the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 1.
Light microscopy images (at a magnification of 20×) of the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 2.
Viscosity as a function of shear rate for the film-forming matrices at 25 °C: (A) pure WS, wheat flours with different gluten contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different gluten contents (8.5%, 11.0%, and 12.2%). Low-gluten wheat flour, LF; medium-gluten wheat flour, MF; high-gluten wheat flour, HF; WS–gluten blend with 8.5% gluten content, 8.5% blend; WS–gluten blend with 11.0% gluten content, 11.0% blend; WS–gluten blend with 12.2% gluten content, 12.2% blend.
Figure 2.
Viscosity as a function of shear rate for the film-forming matrices at 25 °C: (A) pure WS, wheat flours with different gluten contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different gluten contents (8.5%, 11.0%, and 12.2%). Low-gluten wheat flour, LF; medium-gluten wheat flour, MF; high-gluten wheat flour, HF; WS–gluten blend with 8.5% gluten content, 8.5% blend; WS–gluten blend with 11.0% gluten content, 11.0% blend; WS–gluten blend with 12.2% gluten content, 12.2% blend.
Figure 3.
Storage modulus (G′, solid) and loss modulus (G″, hollow) as a function of strain of the film-forming matrices at a frequency of 1 Hz at 25 °C: (A) pure WS, wheat flours with different protein contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 3.
Storage modulus (G′, solid) and loss modulus (G″, hollow) as a function of strain of the film-forming matrices at a frequency of 1 Hz at 25 °C: (A) pure WS, wheat flours with different protein contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 4.
Storage modulus (G′, square), loss modulus (G″, circle), and tan (triangle) as a function of temperatures for the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 4.
Storage modulus (G′, square), loss modulus (G″, circle), and tan (triangle) as a function of temperatures for the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 5.
Storage modulus (G′, solid) and loss modulus (G″, hollow) as a function of frequency for the film-forming matrices at 25 °C: (A) pure WS, wheat flours with different protein contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 5.
Storage modulus (G′, solid) and loss modulus (G″, hollow) as a function of frequency for the film-forming matrices at 25 °C: (A) pure WS, wheat flours with different protein contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 6.
SAXS patterns and their fitted curves for the films: (A) pure WS, wheat flours with different protein contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 6.
SAXS patterns and their fitted curves for the films: (A) pure WS, wheat flours with different protein contents (8.5%, 11.0%, and 12.2%), and (B) WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 7.
SEM images of the surface for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%) at a magnification of 300×.
Figure 7.
SEM images of the surface for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%) at a magnification of 300×.
Figure 8.
Tensile properties of the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%): (A) elastic modulus, (B) tensile strength, (C) elongation at break. Different letter (a, b, and c) means significant difference (p < 0.05).
Figure 8.
Tensile properties of the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%): (A) elastic modulus, (B) tensile strength, (C) elongation at break. Different letter (a, b, and c) means significant difference (p < 0.05).
Figure 9.
TGA curves (A) and DTG curves (B) for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 9.
TGA curves (A) and DTG curves (B) for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 10.
FTIR spectra for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Figure 10.
FTIR spectra for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Table 1.
Flow behavior index (n), fluid consistency index (K) during increasing shear rate for the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different gluten content (8.5%, 11.0%, and 12.2%) at 25 °C.
Table 1.
Flow behavior index (n), fluid consistency index (K) during increasing shear rate for the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different gluten content (8.5%, 11.0%, and 12.2%) at 25 °C.
Gluten Content (%) | Wheat Flours | WS–Gluten Blends |
---|
n | K | R2 | n | K | R2 |
---|
0 | 0.155 ± 0.012 a | 4.159 ± 0.244 e | 0.895 | 0.155 ± 0.012 a | 4.159 ± 0.244 e | 0.895 |
8.5 | 0.349 ± 0.007 d | 1.598 ± 0.036 c | 0.999 | 0.250 ± 0.010 b | 1.825 ± 0.031 d | 0.988 |
11.0 | 0.352 ± 0.014 d | 1.203 ± 0.055 ab | 1.000 | 0.264 ± 0.007 bc | 1.364 ± 0.031 b | 0.988 |
12.2 | 0.380 ± 0.014 e | 1.120 ± 0.055 a | 0.998 | 0.276 ± 0.003 c | 1.349 ± 0.045 b | 0.991 |
Table 2.
Values of n′, n″, G0′, and G0″ for the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different gluten content (8.5%, 11.0%, and 12.2%) at 25 °C.
Table 2.
Values of n′, n″, G0′, and G0″ for the film-forming matrices of pure WS, wheat flours, and WS–gluten blends with different gluten content (8.5%, 11.0%, and 12.2%) at 25 °C.
Sample | n′ | G0′ | R2 | n″ | G0″ | R2 |
---|
WS | 0.0837 ± 0.000 a | 117.695 ± 3.005 e | 0.9999 | 0.1760 ± 0.006 a | 12.948 ± 1.394 c | 0.9645 |
LF | 0.2048 ± 0.011 c | 11.356 ± 0.094 bc | 0.9926 | 0.4223 ± 0.003 d | 2.895 ± 0.041 a | 0.9981 |
MF | 0.2241 ± 0.002 d | 7.942 ± 0.312 ab | 0.9986 | 0.3772 ± 0.001 c | 2.312 ± 0.074 a | 0.9996 |
HF | 0.2801 ± 0.006 f | 6.525 ± 0.175 a | 0.9987 | 0.3546 ± 0.004 b | 2.706 ± 0.021 a | 0.9992 |
8.5% Blend | 0.1496 ± 0.003 b | 25.951 ± 2.342 d | 0.9977 | 0.3412 ± 0.015 b | 4.677 ± 0.431 b | 0.9969 |
11.0% Blend | 0.2043 ± 0.002 c | 14.275 ± 0.643 c | 0.9972 | 0.3940 ± 0.008 c | 3.273 ± 0.121 a | 0.9964 |
12.2% Blend | 0.2535 ± 0.000 e | 8.370 ± 0.148 ab | 0.9945 | 0.3922 ± 0.005 c | 2.245 ± 0.025 a | 0.9989 |
Table 3.
Fractal structure parameters for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Table 3.
Fractal structure parameters for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Gluten Content (%) | Fractal Dimension (D) |
---|
Wheat Flours | WS–Gluten Blends |
---|
0 | 2.56 | 2.56 |
8.5 | 2.44 | 2.43 |
11.0 | 2.31 | 2.27 |
12.2 | 2.25 | 2.20 |
Table 4.
Water vapor permeability for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Table 4.
Water vapor permeability for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Gluten Content (%) | WVP (g·cm/cm2·s·pa) |
---|
Wheat Flours | WS–Gluten Blends |
---|
0 | 1.647 ± 0.043 a | 1.647 ± 0.043 a |
8.5 | 1.738 ± 0.013 b | 1.687 ± 0.045 ab |
11.0 | 1.984 ± 0.043 d | 1.718 ± 0.023 b |
12.2 | 2.003 ± 0.052 d | 1.89 ± 0.007 c |
Table 5.
Specifications of wheat flours and gluten used in this work (obtained from the manufacturer).
Table 5.
Specifications of wheat flours and gluten used in this work (obtained from the manufacturer).
Sample | Starch Content (wt%) | Gluten Content (wt%) | Fat Content (wt%) |
---|
LF | 74.6 | 8.5 | 1.0 |
MF | 73.5 | 11.0 | 1.6 |
HF | 73.0 | 12.2 | 1.6 |
Gluten | 12.5 | 80.6 | 0.8 |
Table 6.
Thicknesses for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Table 6.
Thicknesses for the films of pure WS, wheat flours, and WS–gluten blends with different protein contents (8.5%, 11.0%, and 12.2%).
Gluten Content (%) | Thickness (mm) |
---|
Wheat Flour | WS–Gluten Blend |
---|
0 | 0.074 ± 0.002 a | 0.074 ± 0.002 a |
8.5 | 0.083 ± 0.003 b | 0.096 ± 0.001 d |
11.0 | 0.091 ± 0.004 c | 0.102 ± 0.003 e |
12.2 | 0.102 ± 0.002 e | 0.109 ± 0.002 f |