Zhanhui Lu

The Effects of Vital Wheat Gluten and Transglutaminase on the Thermomechanical and Dynamic Rheological Properties of Buckwheat Dough

The improvement of the processing properties of gluten-free cereals is a challenging issue for cereal technologists. Vital wheat gluten (VWG), transglutaminase (TGase), or combinations of the two have been successfully used to improve the processing properties of food materials. In this study, a Mixolab system and a rheometer were used to investigate the effects of TGase on the thermomechanical and dynamic rheological properties of buckwheat flour dough (BF dough) and a buckwheat flour dough containing 15% VWG (BF-VWG dough). The results indicated that the addition of 1.0% TGase decreased the water absorption and significantly increased the stability, storage modulus (G′), and complex modulus (|G*|) of the BF dough. The presence of 15% VWG had a synergistic effect, enhancing the effectiveness of the TGase in improving the thermomechanical and dynamic rheological properties of the BF-VWG dough. Quantification of the free amino groups showed that the amino groups were more effectively bonded in the BF-VWG dough than in the BF dough when the TGase level exceeded 1.0%. Confocal laser scanning microscopy (CLSM) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis confirmed that the TGase promoted the formation of protein complexes. These data indicate that the combination of VWG and TGase can be used to improve the properties of buckwheat flour for buckwheat-based food production.

Rheological Properties of Fermented Rice Flour Gel

ABSTRACT To clarify the rheological properties of fermented rice noodle (sour mifen) produced in South China, we studied the mechanical properties of gels made from fermented and nonfermented (control) rice flours using static tensile testing, two-bite testing, and dynamic viscoelastic measurement. Rheological measurement under large deformation showed that retrogradation in fermented rice gel proceeded more slowly than in nonfermented rice gel. Lower hardness and brittleness and higher cohesiveness and resilience (degree of recovery) for gels made from fermented rice flour demonstrated that the gel was less firm but more elastic and flexible. Storage moduli of both types of gel increased with time, but the starch retrogradation was suppressed for fermented rice gel. Fermented rice gel exhibited higher resilience and lower rigidity than nonfermented gel, thus the gel stability improved. The chemical analysis of both starches suggests that the partial hydrolysis of amylopectin occurred during the fermentat...

Elucidation of Fermentation Effect on Rice Noodles Using Combined Dynamic Viscoelasticity and Thermal Analyses

ABSTRACT Natural fermentation of whole polished rice grains (indica) is a traditional processing method widely applied in China and South Asia to improve the texture of rice noodles. To elucidate the effects of fermentation on noodle texture, thermal analysis of rice flour and rheological measurement were performed on a gel made from the rice flour with the same solids concentration as practical noodles. The test method proved useful for monitoring starch granule swelling, gel forming, and retrogradation of rice gels during rice noodle production. Dynamic viscoelasticity in a temperature ramp sweep test showed that starch granules of the fermented sample swelled more and were more resistant to breakdown than those of the nonfermented sample. Differential scanning calorimetry revealed that the gelatinization temperature of fermented rice flour shifted to a lower temperature. The decreased protein content after fermentation also played a role in the modified rheological and thermal properties of fermented r...

Suitability of Different Starches for Production of Kuanfen (Chinese Flat Starch Noodles)

ABSTRACT Starches from potato, corn, sweet potato, and rice were compared with mung bean starch for their suitability for producing kuanfen, Chinese flat starch noodles. Significant differences were found in the chemical composition and swelling power among starches (P < 0.05). Maximum tensile stress and maximum tensile strain was highest for kuanfen made from mung bean starch and sweet potato starch, respectively. Higher work was needed to break kuanfen made from mung bean and sweet potato starches. Kuanfen made from mung bean starch was most favored by panelists, followed by those from sweet potato starch. General acceptability of kuanfen correlated positively and significantly with chewiness, cohesiveness, and elasticity of the noodles. For predicting sensory acceptability of kuanfen using instrumental methods, correlation was performed between sensory variables and tensile parameters. Results showed that work-to-break correlated significantly with chewiness, elasticity, and general acceptability while...