Mixer upgrade improves bread quality
Date: 06 January 2006
Baker Perkins' quality-enhancing and cost-saving technique of pressure/vacuum mixing is now available as a retrofit packaging for the Tweedy range of mixing systems.
This new capability covers all the mixers in the current Tweedy range, and also older machines installed before the introduction of the pressure/vacuum process.
Pressure/vacuum mixing has made a major impact in bakeries throughout the UK and continental Europe, Africa and Australasia. Retrofitting the process will enable bakeries to maintain their competitive edge without the need to replace machinery before the end of its natural life cycle.
The benefits of pressure/vacuum mixing include increased yield as dough is more machineable at a higher water content; improved crumb colour and softness - and hence improved shelf life; and a reduction in expensive Ascorbic Acid normally used to aid oxidation.
A retrofit package was piloted on a Tweedy mixer installed in a leading plant bakery; extensive trials produced the same process benefits as those achieved on new machines, and the bakery quickly added the pressure/vacuum option to the rest of the Tweedy mixers installed in the group.
The upgrade package includes a new mixing bowl and lid clamp arrangement, a pressure/vacuum blower and pipework, and strengthening of the mixer frame. The control element will involve either a modification package, or new customised controls, depending on existing arrangements. Each upgrade is individually specified after an initial site survey by Baker Perkins engineers.
The pressure/vacuum process involves application of pressure and vacuum sequentially to the mixing bowl. Air is occluded into the dough by pressurising the bowl in the first part of the cycle, providing more oxygen to enhance the operation of Ascorbic Acid as the oxidising agent. In the second mixing phase, partial vacuum controls the size of the bubbles in the dough to refine the crumb structure.
The pressure and vacuum stages of the cycle can be adjusted so that the full range of structures can be produced, from open-structured breads such as baguettes to pan breads with close and uniform structures.
Traditional process control characteristics - flour/water weight proportioning, accurate water blending and energy control - are all retained.
'Tweedy' mixers are marketed as a complete dough production system, from ingredient weighing to dough delivery to the divider. Optional automatic weighing and feeding of ingredients such as yeast, liquid flour brew, fats, oils, vinegar, improvers and salt can be incorporated into the system software and taken into account in the energy calculations that achieve the ideal dough temperature. Their use is also accounted for in the management information generated.
These mixers are suitable for bulk fermented, accelerated or mechanically developed doughs, using wheat or wheat/rye flour blends in bread, rolls, hamburger buns and pizzas. They are also suitable for pastry and cake mixing.
The five machines in the range have maximum batch sizes between 170 and 385kg, and maximum outputs reaching over 5,000 kg/hour Tweedy mixers are part of a range of market-leading equipment focused on improving bread quality through gentle handling.
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