Cereal Chem 72:516-522 |
Effect of Mixing Conditions on the Quality of Dough and Biscuits.
A. S. Contamine, J. Abecassis, M.-H. Morel, B. Vergnes, and A. Verel. Copyright 1995 by the American Association of Cereal Chemists, Inc.
The effect of energy input during mixing on the standard French biscuit petit beurre was observed by means of an experimental mixer fitted out with monitoring devices. Results showed an energy threshold of approximately 60 kJ/kg, beyond which the biscuits retracted and grew thicker. This phenomenon was accurately studied by a rheological and physicochemical characterization of the dough. The viscoelastic properties of the biscuit dough were determined by dynamic measurements on a parallel plate rheometer The parameter tg delta (G"/G') decreased proportionally to the mixing energy, indicating an increase in the elasticity of the material. Consequently, doughs characterized by tg delta values greater than 0.48 are of poor quality, producing short and thick biscuits that are unsuitable for packaging. For low strains, G' is higher than G", whereas for high strains, the rheological behavior is modified (G" greater than G'), indicating a change in the structure of the material. The value of the limit deformation D corresponding to the point of intersection of the curves G' and G" depends on the energy input during mixing. The development of the gluten network was indirectly characterized by continuous measurements of the extractability of lipids by hexane. The more energy is absorbed by the dough and the more the gluten network develops, the smaller the amount of extractable lipids. Doughs that retain less than 80% of their lipids produce biscuits of poor dimensional stability.