April 01, 2009
by Shane Whitaker
Whether a bakery makes cakes, muffins, brownies, pancakes or waffles, these products all begin as batter. OK, they actually start as raw ingredients, but as soon as the process begins, those materials are incorporated into a batter. To finish with the best product, the batter has to be mixed and portioned properly. New innovations and equipment designs significantly improve systems for processing batters.
A wide variety of batter-processing equipment is available to work with all kinds of batters. Processors want industrial batter-processing equipment that is versatile and easy to sanitize and maintain, as well as provides accuracy and precision to reduce giveaway and waste.
MIXING IT UP. Batter can be mixed in a variety of equipment. Horizontal, vertical and continuous mix systems all may be used in the first step of batter processing. Double-sigma horizontal mixers are probably the least-used option for incorporating ingredients together into a batter, but they are an alternative.
Vertical, or planetary, mixers are more commonly used. "The planetary mixer is the most flexible mixer because it can mix any type or density of product from very light batter to a very dense product," said Kevin Wilkinson, president of Tonelli Group, Woodside, CA. "It can handle products with fruits or nuts, for instance."
Tonelli is known for its high-speed planetary mixers that range in size from 120 to 1,300 l. These mixers offer batch capacities ranging from 150 to 2,500 lb, and the typical size for US bakers is a 600-l mixer making 1,000 lb per batch. Tonelli planetary mixers are capable of doing as many as 12 batches per hour because they use two tools and a scraper blade, reducing mixing times because of increased agitation within the bowl. The comapny offers a wide variety of implements for its mixers, and its staff works with its customers to select the best tools for their products. Bakers can either use two of the same tools or two different tools. "For example, we have one common setup that uses a large spiral to lift the product slowly off the bottom of the bowl and then a flat paddle blends it," Mr. Wilkinson said.
These mixers also feature variable-frequency drives and Allen-Bradley touch-screen controls, so bakers can program multistep process into the system and recall these with the touch of a button. "The first process may be low rpm blending of dry ingredients, while the second step is a higher rpm mix," Mr. Wilkinson explained. "The third phase is higher rpm yet, as we are automatically metering in oil, eggs or liquids and then ramping up to a very high rpm for a period of time. We can have up to 15 phases in each mix, so the mixer can accommodate very complex multiphase mixing processes."
Continuous mixers are often used for manufacturing batters, and this process generally begins in a slurry mixer, which incorporates fats, oils, flour, water, eggs and other batter ingredients into a homogenous mix. Bob Peck, vice-president of engineering at E.T. Oakes, Hauppauge, NY, said a slurry mixer imparts medium sheer upon the ingredients. Slurry mixers feature a rotary blade with paddles that go between stationary implements, known as stator blades. It is an efficient process and mixes ingredients quickly, according to Mr. Peck.
E.T. Oakes is integrating PLCs on its slurry and continuous mixers. Operators can choose different mix times and procedures for staging batter from the user-friendly touch-screen controls, he said.
Matt Zielsdorf, vice-president, sales and marketing, The Peerless Group, Sidney, OH, pointed out that how a company loads and pumps materials out of the slurry mixer will determine the number of batches it is capable of making each hour. The biggest slurry mixer made by Fedco, a division of Peerless, is a 2,000-lb mixer, and some of its customers are producing in excess of 10,000 lb of batter per hour on this mixer.
CLEANING IT UP. Some of the most recent advances made to Fedco’s slurry mixers have focused on improving sanitation. Peerless was challenged by a client to reduce the amount of water needed to clean the machine, and the OEM was able to meet this test by changing the discharges on the mixers and the radius on the bottom of the bowl as well as by improving the seal designs. "We have flush-mounted stator blades and a flush mount on the outlet where batter discharges from the mixer; therefore, you don’t have pockets anymore where batter, flour, sugar or shortening can collect," Mr. Zielsdorf explained.
Mr. Peck noted that more of his clients also want mixers that can be cleaned in place. "We are making provisions to work with clean-in-place (CIP) systems and are mounting extra valves for CIP."
Tonelli also has fully automated CIP systems on both its planetary and continuous mixers. Its continuous mixers are pre-plumbed for CIP, as well as washdown, Mr. Wilkinson said.
After ingredients are incorporated in a slurry mixer, they are generally transferred to a holding tank via a positive-displacement pump. "Our rule of thumb is the holding tank should be 1.6 times the size of the slurry mixer because you want to be able to get that batch out of the slurry mixer and start loading and mixing the next batch while the depositor is calling for batter from the holding tank or continuous mixer," Mr. Zielsdorf said.
Continuous mixers are used to aerate batters and to give the batter a consistent specific gravity. However, continuous mixers cannot handle batters with inclusions because the high shear of these mixers will pulverize large particulates such as blueberries or nuts. Also, dense batters such as those for loaf cakes or muffins generally do not need to be aerated. However, continuous mixers are ideal for layer cake batters that require an aerated batter.
One thing that sets the Fedco continuous mixer apart from others is that its rotors and stators begin as a stainless cast that is then machined, according to Mr. Zielsdorf. "It is not a fabricated process; it is a machined process," he said. "Our teeth are pure metal, and they are machined out of a stainless steel cast, so we don’t have a process where we fabricate or weld pins to a shaft. Our design results in lower rpms per mixing speed to get the same shear. It is a much more condensed head, so product has to spend less time in the head, which generates less heat."
If a processor wants to use a continuous mixer yet still have particulates in the final product, E.T. Oakes offers an option to take the aerated dough through an inclined mixer, which is a bowl-type mixer where inclusions can gently be folded into the batter. This system would then use a sine pump, featuring special rotors to gently pump the product without destroying the particulates, according to Mr. Peck. "You can pump whole strawberries without damaging them," he observed.
SERVING IT UP. Delicate handling of batters is a top priority for bakers because they do not want products condensed, said Rod Gregg, general sales manager, Hinds-Bock Corp., Bothell, WA. The company manufactures industrial depositors, and its equipment features large open flow passes all the way through the machines, he said. "Bakeries want to make gourmet muffins or cake products that look handmade and to do that they increase the size of the particulates, so we have to increase the size of the opening in our machines," Mr. Gregg added.
Viscositywise, he pointed out that batters over the past few years have tended to become thicker. To portion these batters at high rates of speeds into pans or muffin cups without having the product tail or drip over the edge can be challenging. "We do that with specialized diving nozzles on our machine." Mr. Gregg said. "We literally dive the nozzles down into the pans, make our deposit and lift up to break off any product so it doesn’t string from one row to the next. That is a unique feature that not many depositing companies offer."
A clean cutoff is important to a baker because if batter tails, it can weld paper liners to pans, and when the product is depanned, it can break, leading to wasted product. Also, because ingredient costs have skyrocketed, bakers want to ensure that they are not giving away extra product, thus they demand depositors be extremely accurate.
"Typically in our industry we are asked for ±1% accuracy," Mr. Gregg said. "We have individual measuring chambers on our machines, so each nozzle has a piston and cylinder measuring the product, and that is how we control accuracy on a multiple deposit."
Peerless recently developed a new batter depositor that uses coriolis mass flow meters to control the deposit. The Fedco Next Generation Depositor (NGD) can run at much higher speeds than a piston depositor, according to Mr. Zielsdorf. However, accuracy is probably the greatest feature of this new depositor. A coriolis flow meter measures the mass of the product flowing through a tube as opposed to measuring volume as in a traditional piston depositor. The NGD has been able to achieve a standard deviation of less than 0.1 oz on a 14-oz deposit, he noted. Because companies may drastically reduce product giveaway with the patent-pending depositor, Mr. Zielsdof said, "It is going to have a payback for some people inside of a month."
The new depositor also features a tool-less quick-change conveyor belt, and the new design is CIP, meets BISSC standards and has very few moving parts. "We’ve eliminated the hopper above the deposit heads and use a bypass manifold/circulation to maintain constant pressure and a continuous ready-to-deposit mode," Mr. Zielsdorf added.
Bakers desire greater flexibility from the software programs and the depositors, and they want PLCs with password protection, according to Mr. Gregg.
Processors also want output counts on the controls that tell the number of cakes or muffins or deposits made per run. "If they monitor the output daily on specific products, they can calculate the number of cycles on the machine per day, per week, per month, and it tells them when to do their maintenance," Mr. Gregg said.
From a sanitation standpoint, Hinds-Bock manufactures its hoppers so that they clamp down instead of bolt on. The hopper is also on hinges, allowing the operator to unclamp the machine and tilt back the hopper to clean it. "Also, once it is tilted off the head of the machine, it exposes the internal components of the depositor, making it easier to take apart and clean," Mr. Gregg explained.
Many exciting developments to batter mixing and depositing equipment are taking place, and if your bakery is making a product with batter, it very well may be worth further investigating some of these advances in equipment design.
This article can also be found in the digital edition of Baking & Snack, April 1, 2009, starting on Page 82. Click here to search that archive.