The Versatile, Adaptable Tweedy Mixer
Wednesday, October 11th, 2017
The range of Tweedy mixers can help all bakery manufacturers improve their production efficiency while saving costs and maintaining safety. By Keith Graham, marketing manager, Baker Perkins
The Baker Perkins range of Tweedy high-speed mixers provides a broad range of doughs for a diverse range of bakery products throughout the industry, from small through medium to large scale plant bakeries.
These versatile mixing systems are most usually associated with high-speed, high-energy mixing in plant-scale tin bread bakeries, where they are used for the complete range of pan and tin bread doughs including white, brown, wholemeal, multigrain and mixed rye loaves.
However, several integral features make the Tweedy process ideal for many other products, including pizza, baguette, focaccia, ciabatta, batter, rye, soda, pita and artisan breads, brioche, breadcrumbs and Panko, bagels, cinnamon rolls and burger buns. The scope is still being extended.
A Versatile Machine
The Baker Perkins Tweedy is a completely integrated mixing system in which ingredient weighing, mixing and dough development takes place rapidly and seamlessly. High-speed mixing is the key to a number of fundamental advantages which lead to consistent high quality and low production costs.
Minimised Production Time
The Tweedy typically mixes and develops a batch of dough in three minutes; while one batch is mixing, another is being automatically weighed out. Short mixing cycles are a decisive advantage because the mixing process is rapid and batch sizes are small for a given output; each batch is processed through the divider and moulder before significant fermentation (or ‘gassing up’) can begin. This helps to achieve accurate weight control and consistent texture as well as easier downstream handling.
Automated ingredient feeds minimise dead-time, while the design of the bowl and beater—plus the speed of rotation—combine to produce a 3D mixing action that stretches and shears more of the dough for more of the time than in conventional mixers. The result is rapid structural development that allows up to 12 batches every hour. The process is the same as in conventional mixers—just much quicker.
Flexible Across Applications
Pressure/vacuum mixing controlling the dough texture is another fundamental Tweedy benefit. Achieving comprehensive development in the mixer involves the use of pressure and/or vacuum sequentially in the mixing cycle. By pressurising the bowl in the first mixing phase, more air is added, providing oxygen to enhance the action of ascorbic acid, which improves development and gas retention in the dough. Vacuum in the latter stages helps create very precise control over the size of bubbles in the dough to refine the crumb structure of the finished product.
The proportion of pressure and vacuum applied determines whether the dough texture is fine (e.g. for bagels or close-grained pan bread) or open (e.g. such as baguettes and artisan style loaves). And because these proportions are simply altered, it is easy to switch to a different product, say between an open textured deep pan pizza and a denser crispy pizza base.
Clean And Safe
Rapid product changeover is a benefit to every baker, particularly where a variety of products are needed each day. A time-saving automatic washout system developed for the mixing bowl gives a really effective cleaning action and eliminates operator involvement.
This rapid, thorough and fully automatic cleaning cycle means that the machine minimises downtime when making products where cross-contamination could cause quality or food safety problems. For example: coloured breadcrumb coatings for fish and meat, or products containing allergens such as nuts, eggs or dairy.
A further significant benefit is that the Tweedy mixer can produce good quality dough with lower protein flour because mixing is much more thorough. A combination of high-speed beater and baffles on the periphery of the mixing bowl simultaneously work a very high percentage of gluten molecules in the dough during the dough development stage of the process. This creates the potential to use flour with lower protein content, or reduce/eliminate additions of vital wheat gluten—both meaningful cost savings.
There are other benefits. There is fully automatic feed and discharge, schedule management without operator intervention, and a comprehensive automatic control system that includes storage and one touch loading of recipes and schedules. Hygiene and maintenance are simple—a wash-in-place system for the bowl and lid is much more thorough and rapid than manual cleaning.
One For Every Purpose
The range of Tweedy mixers covers the industry. The largest mixer has a 385 kg batch capacity and an output up to 5,400 kg/hr while the smallest offers a 170 kg batch size and 2,400 kg/hr. There is also the Tweedy 50 for small batch production.
The latest development is the introduction of two machines for test and laboratory applications. The Tweedy 8 and Tweedy 20 have maximum batch capacities of 8 kg and 20 kg respectively.
For bakeries looking to switch to the high-speed Tweedy process, these are ideal machines to try out the technology to ensure it will replicate their existing product range.
They are also intended for use by ingredient suppliers working on new formulations to improve high-speed mixing and research organisations studying high speed mixing and other aspects of the bread making process. Applications in artisan scale bakeries, bagel, pastry and other bakery sectors are also anticipated.
The small batch size is ideal for research and testing purposes: a viewing port in the lid allows progress of the mix cycle to be monitored and process parameters can be repeatedly changed to analyse and assess results. For even greater flexibility the batch size may be reduced by up to 50 percent without affecting the process.
All the important process control features found on the production mixers are incorporated, including variable speed control and pressure-vacuum mixing for enhanced texture control. This allows exact replication of the process of production systems, enabling successful scaling up to full production.
Tweedy mixers, plus proving and baking facilities, are installed at Baker Perkins Innovation Centre in Peterborough in the UK. Customers can bring their own ingredients to try out any kind of recipe.
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