Doughs for soft baked goods are mixed intensively. The gluten network should be well developed to achieve a uniform crumb texture. Sometimes, the doughs are slightly overmixed, which results in plastic and flowable doughs. This ensures that the moulds are evenly filled with dough. This effect is known as the “pan flow” effect. Doughs containing fat and sugar require slightly more intensive mixing, as the build-up of the gluten network is delayed by the amounts of fat and sugar. Spiral mixers, twisting mixers or horizontal mixers are used in the batch system in plant bakeries. Particularly in areas where wheat flour is very rich in gluten (USA, South-East Asia, Australia), horizontal mixers performing intensive mixing are mostly used.
A distinctive method is the Chorleywood Bread Process. This process, developed in Chorleywood, England, is used to achieve a particularly fine and cotton wool-like crumb texture, a light-coloured crumb and a high specific volume of baked goods. This involves intensive mixing in special vertical mixers with various pressure curves (partial vacuum to overpressure). The mixing time depends on the amount of energy applied and is 150 to 180 seconds. The doughs are processed without bulk fermentation time.
A distinction is made between vacuum mixing and pressure-vacuum mixing. With vacuum mixing, the pressure in the mixing chamber is reduced to approx. 0.5 bar after the first mixing phase (25 to 45 seconds) while the mixing process continues. Mixing then continues at normal pressure. The gas bubbles, which are initially enlarged by the vacuum, are split into small, fine gas bubbles and distributed evenly throughout the dough.
In pressure-vacuum mixing, the dough is mixed with a slight overpressure (approx. 1.4 bar) after the dough formation phase. The main purpose of the pressure phase is to improve the oxidation of the gluten and the development of the gluten network. The pressure in the mixing chamber is then reduced to approx. 0.5 bar, leading to an enlargement of the gas bubbles and subsequent splitting into small gas bubbles. These are compressed at the end of the mixing process. The effects with regard to the fine crumb texture are enhanced by pressure-vacuum mixing.
