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Biaxial Extensional Viscosity of Sheeted Noodle Dough

¹Assistant professor, Department of Food Science, China Institute of Technology, 245, Yen-Chiu-Yuan (Academia), Nankang, Taipei City 115, Taiwan, ROC. ²Corresponding author. Phone: 886-227821862 Ext 274. E-mail: markliao@cc.chit.edu.tw. ³Associate professor, Department of Biological Science & Technology, China Institute of Technology, Taipei City 115, Taiwan, ROC. ⁴Faculty of Science, Department of Food Technology, Chulalongkorn University, Bangkok, 10330 Thailand.

The flows encountered during the sheeting process contain a more extensional component and more stretching than simple shear. Evaluating the properties of the extensional rheological flow of wheat flour dough is essential to better understand the sheeting process and the final quality of the product. Our results show that the curves of biaxial extensional viscosity versus extensional strain rate for dough from different wheat cultivars including Dark Northern Spring (DNS), Hard Red Winter (HRW), and Western White Wheat (WW) with protein contents of 7.81–18.09% and water contents of 32–40% could be discriminated. During a lubricated compression test, the sheeted dough displayed a region of extensional thickening followed by a region of mild extensional thinning, giving rise to an s-shaped extensional stress-strain rate curve. The higher degree of extensional thinning was exhibited for the sheeted dough prepared from the flour of DNS and HRW wheat mixture with an extensional thinning index of n = 0.65–0.74; while the lower degree of extensional thinning was displayed for the DNS wheat with an extensional thinning index of n = 0.89–0.96. The data of biaxial extensional viscosity (η_Bmax) versus water content and protein content could be described by power relationships. The results suggest that biaxial extensional viscosity can be a useful modeling and process design parameter that objectively represents the rheological properties during dough sheeting.