TU Munich: Process design using forced dough relaxation

Figure 3: Infuence of the dough resting time or forced relaxation (ultrasound or alternating voltage) between kneading and processing on the pore pattern of tin loaf white bread. Illustration in a), as well as evaluation of the number of pores and the area percentage of the pores on the total surface of the bread slice in b).

(results not shown). Likewise, after baking, there are also effects equivalent to resting time for ultrasonically treated doughs with regard to volume and crumb hardness. However, the effect of ultrasonic treatment is significantly lower compared to stress treatment. This also becomes apparent when the pore pattern of the reference breads with 0 and 10 minute rest time between kneading and processing is compared with the pore pattern of the forced relaxed breads (Fig. 3 a)). The 10 to 20-minute rest period between kneading and processing gives the breads a coarser-pore structure. This can also be seen from the decrease in the number of pores with a simultaneous increase in the proportion of pores in the total area of the bread slice (Fig. 3 b)). The pores are thus reduced in total by the resting period, but become larger. A nearly identical effect as a 20-minute resting period becomes apparent for the voltage treatment. This can be seen visually as well as via the non-significantly different number and area of pores. The ultrasound treatment also shows a resting time equivalent effect on the pore pattern, but this corresponds to a resting time of about 10 minutes. With the results of the baking tests, the effects of forced relaxation on structure and/or yeast damage can be excluded and bread properties (volume, crumb hardness, pore structure) can be demonstrated to be equivalent to those of dough that has been left to rest.

The easy applicability and short application time (1-60 sec) of the electrical/mechanical impulses allows the integration of the dough resting step into the running process. This leads to a simplified and more effective process in terms of plant effort and time. The detailed micro- and macrostructural analyses, some of which are presented here, consisting of rheological analyses, strain measurement, microscopic methods and baking tests, have clarified the underlying functional mechanisms of forced dough relaxation for different flour qualities. Based on the presented shortening potential, existing process sequences in bakeries were evaluated with respect to their suitability (dwell time for application of the impulses) for the integration of the relaxation methods: Conveyor and transport belts in particular proved to be suitable application points. In summary, the forced dough relaxation is a method that allows for the elasticity, softness and resilience of wheat doughs in a few seconds without significantly changing the gas release and holding capacity of the products. +++

This IGF Project of the FEI is/was supported via AiF within the program for promoting the Industrial Collective Research (IGF) of the German Ministry of Economic Affairs and Energy (BMWi), based on a resolution of the German Parliament. Pro-ject AiF 18565N

Literature notes

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Confectionery-Management, vol 5 Gildebuchverl., Alfeld 4 Klingler RW (2010) Fundamentals of Grain Technology, 2nd, fully revised edition Behr, Hamburg 5 Zentralverband des Deutschen Bäckerhandwerks e. V. Facts & Figures -

Bakery trade – Baker's trade. COSMOTO | Lime Flavour.

Authors:

S. Brandner, T. Becker, M. Jekle Technical University of Munich, Institute of Brewing and Beverage Technology, Research Group Cereal Technology and Process Engineering 85354 Freising, Germany; contact: mjekle@tum.de

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