Energy Transfer in CBP/MDD Mixing Equipment – Managing Dough Development

Presented as part of Technology Transfer Seminars 2023

Stan followed up his thought-provoking first presentation with a second talk about the controversial subject of energy transfer during dough mixing. The key in all cases, he said, is understanding the concept as well as the consequences of energy transfer during mixing.

90% of final bread quality is determined by what the baker chooses to do in the mixer. Dough development can’t be undone. After the dough has left the mixer, there is almost nothing the baker can do to compensate with changes in dough processing for errors in the mix, so getting it right first time is crucial.

Stan revised what goes on during mixing, starting with the dispersion and uniform blending of ingredients, and going on to cover the hydration of flour protein to form gluten, hydration of damaged starch, delivery of energy as part of dough development, incorporation of air and initiation of oxidation, creation of gas bubble structures, and the final dough temperature being higher than the sum of the ingredient temperatures, the control of which has serious implications in practical terms.

Stan shared his “house of bread quality” concept, in which the strength begins with the foundation of the development of the gluten network through the transfer of energy – work input – and the control of final dough temperature. The “walls”, he said, are the ascorbic acid-assisted oxidation of the gluten network coming from the gas that is incorporated in large quantities through mixing, and oxygen, the presence of which is an important part of the AA oxidation. The “roof” is made up of improvers that are usually expensive so there is a need to use as little as possible. Inside the “house” are the gas bubbles created during the mixing process which will grow and develop.

The whole of the baking process, Stan emphasised, is about creating a set of conditions which we don’t know quite know the outcome of until the dough goes into the oven and comes out again. He stressed the need for bakers to be consistent in the bakery too, rather than just asking flour millers to provide consistent flour.

He discussed in detail mechanical dough development, work input versus mixing time, the impact of mixing speed on crumb structure, the role of energy in dough development, the two approaches dough temperature of choosing and controlling, and then went on to elaborate on the principles and practice of controlling dough temperature. Further topics were the effect of ingredients on dough rheology, gas volume incorporated during mixing, the contribution of pressure control, cell creation and crumb structure control, and controlling oxidation and structure.

Stan’s final topic was one that could be particularly useful to bakers – how understanding mixing curves helps understand dough development and working out exactly what is happening in the mixer. He looped back to his previous presentation to emphasise that the analytical data are not wrong. The problem is that the right things are not being measured to allow prediction of baking quality.

He concluded by reiterating that it is not just about controlling energy, it is about understanding a whole series of complicated relationships occurring during the dough mixing process, all of which contribute to final bread quality.

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