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Rheological Properties of Fermented Rice Flour Gel

¹College of Food Science and Nutritional Engineering, China Agricultural University, PO Box 40, Beijing 100083, China. ²Food Physics Laboratory, National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan. ³Present address: School of Life Science, Jiangxi Science and Technology Normal University, Nanchang 330013, China. ⁴Corresponding author. Fax: +81-29-838-7996. E-mail: kaoruk@affrc.go.jp

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 fermentation process.