dough handling
sponge and dough development. Technosilos highlighted the fact that principle sources of high temperatures can be the heat of hydration (flour absorbing water), heat of friction (mixer motor energy) , and the base temperature of the raw materials. It went on to highlight the wide variety of different technologies that can be employed to control the dough temperature and cool it down. These include: Mixing: The temperature rise during mixing is caused by the penetration of the mixing tool into the dough, and by the friction of the dough against the mixer bowl. Therefore, the design of the mixer and the speed of the tools are critical. To maintain consistency in dough temperature, mixer manufacturers are constantly improving the design of their mixers to reduce the heat of friction. Tools are also available to monitor dough temperature during mixing. The use of temperature sensors is becoming common, working in conjunction with the mixer, usually through a programmable logic controller (PLC), to control the mix time.
Mixers also often incorporate cooling features into their equipment design – for example through the provision of refrigerated jackets on the bowl or refrigerated agitator bars. Water temperature: Chilled water and/or ice can be
used to offset the heat factors of mixing. Indeed, water temperature is the main element that enables bakers to have a direct influence on temperature, as this can be increased or lowered to maintain dough temperature. There are many suppliers of water chillers to choose from. The installation of the system will also be critical, as water temperature at 3°C at the outlet of the chiller can reach 6°C in the mixer. Ice: ice is most often used in summer months when
the flour is at its hottest. It is usually dosed manually and compensates for a volume of water. It is important to remember that the addition of ice will modify the mixing parameters since it takes time to melt and disperse homogeneously in the dough. Flour temperature: This can be subject to change
as a result of carrying and storage conditions. The type of pneumatic transfer also has a role to play in flour temperature. Some facilities offer recirculation of the flour from silo to silo – the air generated by the blowers performs a thermal exchange with the flour during the transfer phase, while modifying the atmosphere in the silos to a dew point. To overcome the heat exchange, suppliers of pneumatic handling systems often offer vacuum conveying without recirculation (dead end receivers). Vacuum conveying typically conveys material at ambient air temperature. Technosilos believes that the optimal solution to
ensure consistent dough temperature is automated flour cooling – units operate on the principle of cryogenic gas injection (liquid carbon dioxide or liquid nitrogen) or by heat exchange with cooled air in a closed circuit. The Delta T (the difference of the temperatures between two measuring points) obtained can go from 8 to 16°C for some models. This means that a flour temperature of 30°C in the silos can be dispensed at 14°C to the mixer.
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systems_2022_Suedback.indd 1 Kennedy’s Bakery Production October/November 2022 12.07.2022 11:49:18 29
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