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Effects of Temperature and Mechanical Input on Semisweet Biscuit (Cookie) Quality and Dough Characteristics¹

¹Research supported in part by a program of Ministère de la Recherche et de la Technologie (MRT) and Institute de Recherches Technologiques Agro-Alimentaires des Céréales (IRTAC), and by Danone France (Branche Biscuit). ²Unité de Technologie des Céréales et des Agropolymères, INRA/ENSAM, 2 place Viala, 34060 Montpellier Cedex 01, France. ³Danone, Centre de Recherche Jean Thèves, 6 rue Edouard Vaillant, 91207 Athis-Mons Cedex, France. ⁴Ecole des Mines de Paris, Centre de mise en Forme des Matériaux, B.P. 207, 06904 Sophia-Antipolis Cedex, France. ⁵Corresponding author. Phone: +33-499-61-25-62. Fax: +33-467-52-20-94. E-mail: morel@ensam.inra.fr.

The effects of specific mechanical energy (SME) and dough temperature at the end of mixing (T_f) on semisweet biscuit dough characteristics and biscuit quality were studied using an experimental mixer fitted with monitoring devices. The fluid circulating in the double jacket of the mixing bowl was regulated at variable temperatures and mixed dough samples were prepared at T_f of 23, 30, and 37°C for three levels of SME input (20, 60 and 120 kJ/kg). Correlation analysis showed that semisweet biscuit length and thickness were independent quality parameters, influenced respectively by the T_f of dough and SME. Biscuit thickness and volume increased with SME input, but SME had no significant influence on the physicochemical characteristics of the dough. Biscuit length was related to the density and stickiness of the dough and to rheological behavior as assessed by fundamental and empirical measurements. A rise in dough temperature >35°C induced a dramatic increase in viscoelastic properties, leading to biscuit shrinkage. The increase of dough density with T_f seemed to be related to the melting of solid fat in the dough recipe. Melting of fat during mixing could also be a source of viscoelastic changes in the dough at T_f.