Evaluation of bread dough aeration during kneading by an air-jet impulse system

Abstract

This paper presents a novel system able to determine in touchless conditions some rheological properties of bread dough, by application of a force driven by a short air-jet impulse, and the concomitant surface displacement measurement by a laser interferometer. In this work, it is shown that in the FPD (Food Puff Device) is based on the displacement measurement due to an air jet by a laser interferometer test, a “softening” of the bread dough along the kneading process is observed, although it is well known that the bread dough gets strengthened by the kneading. This paradox is explained by the fact that, during the kneading, not only the dough become smooth and elastic, but a certain air amount is incorporated in the form of small air bubbles. FPD provides an empirical short time rheology test exciting the time scales linked to the air bubbles entrapped in the dough, so that the surface displacement is mainly due to the dough aeration. Demonstrating a good sensitivity to the air content, the FPD test seems a relevant method to follow the kneading process, in the aim of developing a tractable and efficient supervision tool. The bulk properties of the dough are also measured by a conventional creep recovery test in a rotational rheometer. An attempt of modelling the viscoelastic behavior in FPD treated like a creep-recovery test is proposed here, to provide some insights in the baking monitoring.