Lida Shashavani Mojarrad; Ali Rafe
Abstract
Textural, thermal and microstructural properties of single component gels and binary composite gels (BCG) of high amylose corn starch (Hylon VII) mixed with wheat flour at different wheat flour/Hylon VII (WF/H) ratios (95:5, 90:10 and 85:15) and temperatures (100, 121 and 135ºC) were investigated. ...
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Textural, thermal and microstructural properties of single component gels and binary composite gels (BCG) of high amylose corn starch (Hylon VII) mixed with wheat flour at different wheat flour/Hylon VII (WF/H) ratios (95:5, 90:10 and 85:15) and temperatures (100, 121 and 135ºC) were investigated. The visual appearance showed that as Hylon VII was increased in BCG, the stronger gel was achieved. Textural results confirmed by increasing Hylon VII, the firmness was increased, but the springiness, cohesiveness and adhesiveness were reduced. Moreover, the BCG at high temperatures showed the higher level of Hylon VII, the higher water solubility index would be achieved. The gelatinization enthalpy (ΔH) and peak gelatinization temperature (Tp) increased by improving the content of amylose in BCG. Hylon VII showed the lowest peak viscosity and the BCG gel containing high amount of Hylon VII indicated a reduction in the paste viscosity. The differences in the microstructure of WF and HylonVII gels were also reflected the pasting properties of the gels. Consequently, BCG of WF/H develops the stronger gel which can withstand at high thermal processing such as retort to improve the shelf-life of the final product.
Reza Farahmandfar; Seyed Ali Mortazavi; Farideh Tabatabaei Yazdi; Arash Koocheki
Abstract
In this study, variations of the pasting properties, swelling power and solubility of two rice starches, low amylose (8.7%) and high amylose (26%) at two citric acid concentrations (0 and 0.01 M) was investigated. The results showed that the peak viscosity and breakdown viscosity of rice starch decreased ...
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In this study, variations of the pasting properties, swelling power and solubility of two rice starches, low amylose (8.7%) and high amylose (26%) at two citric acid concentrations (0 and 0.01 M) was investigated. The results showed that the peak viscosity and breakdown viscosity of rice starch decreased significantly (P<0.05) with increased the proportion of amylose while hot past viscosity and cold past viscosity increased significantly (P<0.05). As the concentration of citric acid increased, pasting properties decreased but did not change (P>0.05).The swelling power and solubility of both starch pastes with and without citric acid increased with the increase of the temperature. As the concentration of citric acid increased, swelling power of low and high amylose starch decreased and this event was clearer in low amylose samples. On the other hand, citric acid induced solubility of samples particularly in high amylose rice starches. Furthermore, the swelling power and solubility of treatments decreased and increased with increasing amylose content of rice starch, respectively.
