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Use of Elongational Viscosity to Estimate Cookie Diameter¹

¹Contribution 97-185-J from the Kansas Agricultural Experiment Station, Manhattan, KS. ²Research associate and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ³Corresponding author. Phone: 913/537-5199; Fax: 913/537-7477. E-mail: r_and_r@kansas.net ⁴R&R Research Services, Inc., 8831 Quail Lane, Manhattan, KS 66502.

Cookie diameter is a function of spread rate and set time during baking. Dough viscosity appears to control cookie spread rate and, thus, will affect final cookie diameter. The technique of lubricated uniaxial compression was used to measure the elongational viscosity of cookie dough. Full-formula cookie doughs made with a commercial hard wheat flour had a significantly higher elongational viscosity (5.88 × 10⁶ ± 9.17 × 10⁴ Pa·S) than cookie doughs made with a commercial soft wheat flour (2.17 × 10⁶ ± 1.05 × 10⁴ Pa·S). Elongational viscosity correlated significantly (P < 0.05) with the diameter (r = -0.796) of cookies made with flours from various soft wheat cultivars. Using a simplified cookie formula decreased the testing time without greatly changing the correlation coefficient (r = -0.738). Thus, lubricated uniaxial compression appears to be an appropriate technique to measure the viscosity of cookie doughs and may be useful for predicting the cookie baking quality of soft wheat flours.