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Continuous mixing/aeration systems are typically composed of several separate machines. First, a slurry premixer blends dry and liquid ingredients, which can be added either manually or with automated ingredient handling systems. This medium sheer mixer incorporates oils, flour, water, eggs and other ingredients into a uniform mix.
The slurry is then pumped to an intermediate buffer holding tank, which is often jacketed for cooling and heating. Buffering tanks are available with or without agitation and are generally two to three times as large as the slurry mixer.
Batter from the buffer tank is continuously fed to a continuous/aeration mixer, where air or nitrogen can be mixed at a controlled pressure. The batter or filling exiting the mixing head is measured with an electronic metering device for density and flow rate. Sophisticated control systems can adjust several variables in the continuous mixer, thereby controlling the finished products’ characteristics such as specific gravity, density and temperature.
Continuous batter mixers offer many advantages to bakeries in automation and product consistency. “Continuous mixers allow uninterrupted continuous flow of constant batter or creme topping and fillings at a consistent flow rate and with precise specific gravity and in certain models at consistent temperatures,” said Kevin Wilkinson, president of Tonelli Group, Woodside, CA.
E.T. Oakes Corp., Hauppauge, NY, uses Micro Motion Coriolis flow and density meters to constantly measure the specific gravity of batters as they are pumped to the hopper or depositor. Also, the company’s mixers feature Flowrators to control the amount of air or nitrogen that is being injected into the batter. This computer-controlled system allows processors to maintain their specific gravity, according to Jeremy van Bemmelen, the company’s sales engineer.
Bakeries commonly use continuous mixers when they need constant density, flow rate, specific gravity and temperature of cake batters, whipped toppings, icings and fillings, according to Mr. Wilkinson. “Producers needing high levels of automation with minimal product changeover and longer production cycles generally benefit most from continuous mixers,” he added. “However, it should be noted that Tonelli continuous mixers are also used in smaller operations by customers demanding precise control of their operations. ‘Continuous mixers,’ as the name implies, means continuous production, which allows for high efficiency and product accuracy.”
Continuous batter mixers are not for every operation, and the lack of quick changeovers between products and relatively narrow range of production applications for a specific model can limit the usefulness of continuous mixers in smaller bakeries with a variety of products.
“Continuous mixers, however, are the most efficient way to produce cake batters or creme toppings and fillings for larger producers requiring low labor and consistency in product results such as density, temperature and production rate,” Mr. Wilkinson added.
The Tonelli Group manufactures a wide range of continuous batter and creme mixers for production rates ranging from 350 lb per hour up to 10,000 lb per hour. “Some of the newer Tonelli systems include internal scrapped surface heat exchangers, which allow the production of very cold products and even the option of pasteurizing of dairy products inline in a continuous process of heating, cooling, aerating and depositing,” he said.
The Mondotherm is a scraped surface heat exchanger from Haas Mondomix B.V., Almere, The Netherlands. It continuously heats or cools viscous products or products with particulates. The Mondotherm features a sanitary design with no dead corners and stainless steel product surfaces.
The Peerless Group, Sidney, OH, has focused on improving sanitation of its Fedco continuous mixing systems. After being asked by a client to reduce the amount of water to clean its machines, Peerless redesigned the discharges on the mixers and the radius at the bottom of the bowl as well as improved seal designs. And by using flush-mounted stator blades as well as a flush mount on the batter discharge outlet, the company eliminated pockets where batter, flour, sugar or shortening could collect.
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