by Melissa Hillebrand , assistant editor
Donatos Pizzeria uses a mixer that automatically collects scrap on a conveyor and feeds it into the hopper.
In continuous mixing, ingredients are fed into the mixer nonstop and dough continuously feeds out.
During the last 10 years, advancements in mixing technology have skyrocketed. Mixer manufacturers now can offer bakers more sophistication and control.
Manufacturers can provide mixers that are faster, gentler and sturdier than what was available. These mixers are ideal for handling the new waves of high-fiber and whole grain doughs, due to new mixers' robust designs and efficiencies. They also improve the processing of traditional doughs through better controls and designs.
Continuous, high speed, horizontal and vertical mixers all have undergone transformations to offer bakers stateofthe-art technology and controls.
For bakers who want more efficiency in a high-speed environment, advancements in continuous mixing have evolved. In continuous mixing, ingredients are fed into one end of the mixer nonstop, and dough continuously feeds out of the other end.
These mixers have evolved to handle highly developed doughs, such as sweetgoods, honey buns and whole grains. "Continuous mixers have gone through an evolution so they can offer more mixing, but less sheering," one manufacturer says. "The highly developed doughs don't like the sheering or the tearing action."
High-speed mixing with low sheer is one trend to hit continuous mixing. Another trend in this mixing field is flexibility. With new mixer designs, changes to the mixing profile can be made on the fly while the equipment is running, one manufacturer says. "This is a very important design feature," he says, "because when you go from product A to product B, you want to quickly change the mixer without spending a lot of time in the changeover."
Like continuous mixers, high-speed mixers offer more mixing in less time. One manufacturer offers a mixer that turns the dough at 1,200 rpm. It can mix pizza dough in two minutes, as opposed to 10 minutes for a traditional mixer, the manufacturer says. Because this mixer is so intense, it hydrates the flour and ingredients better, the manufacturer says. This ability to hydrate the dough makes this mixer ideal for handling stiff doughs, such as whole grain or high fiber. "You are not going to get the development of that dough until you get those ingredients fully hydrated," he says. "And they are difficult to hydrate."
This mixer is able to turn fast because it uses a direct drive motor, which spins at 1,200 rpm, and is mounted to the motor shaft. Mixing tools also are attached to the shaft, allowing the mixer to turn at 1,200 rpm. This mixer also features variable speeds. It can run as slow as 150 rpm, if a baker wants to incorporate particulates into the dough.
This high-speed mixer also features an automated system that adds scrap back to the mix. This system trims the dough from the baker's production line, weighs it, and adds the dough to the mixer when the program calls for it.
Donatos Pizzeria LLC took advantage of the benefits of this mixer. Seven years ago, the chain moved dough making from its restaurants to a facility located in Columbus, Ohio. Donatos was using three bowl mixers and needed to expand its capacity. Instead of purchasing a fourth bowl mixer, the company bought an automated high-speed mixer that replaced its existing mixers.
The company used to collect the scrap by hand and place it into the bowl mixers. Now, scrap conveyors gather web trim from the sheet-and-cut pizza shells, move the scrap to one cross conveyor, then discharge the scrap into a chunker hopper once the scrap has reached a certain weight.
"It's all hands-off," says Bob Zaborski, Donatos' executive director of commissary operations. "There's very little physical labor involved with the mixing."
After purchasing the mixer, Donatos' mix times dropped from six and a half minutes to 90 seconds. Furthermore, the company's efficiency increased significantly. "I wrote the project and sold it on what I thought would be an 18% efficiency increase," Zaborski says, "and we actually realized a 35% efficiency increase. What it's done for us is huge."
Horizontal, vertical options
Like continuous and high-speed mixers, horizontal and vertical mixers also have seen advancements. One manufacturer offers a horizontal mixer with a sanitary, open-frame design. This stainless steel system features a direct drive system that has no sprockets, chains, pulleys or belts for the baker to maintain.
New vertical mixers offer advantages for bakers who formulate frozen or highly developed doughs. One manufacturer offers a vertical mixer that adds very little heat to the dough. This mixer has two vertical bars that rotate and intersect while they stretch, compress and intersect the dough. Because this adds very little heat, the dough experiences less friction, and there is less wasted energy, the manufacturer says.
"It has the amazing property to develop the gluten better so the dough will hydrate," the manufacturer says. This feature makes this vertical mixer ideal for highly developed doughs, including laminated doughs.
This manufacturer offers a unique drive system in all of its vertical mixers. They system has a large pulley on the motor with belts driving a parallel axis gearbox. The gearbox, mounted on shock absorbers, changes the speed of the spiral tool. The vertical mixer's structure absorbs the shock, and this translates to a much more secure and strong drive system, the manufacturer says. Secondly, the spiral tools are constructed in a special way where they are strengthened through an annealing process that relaxes the tension normally found when stainless steel is curved.
Advances in controls
In addition to design advances, improvements have been made in mixer technology. One advancement allows bakers to mix doughs to an energy level, as opposed to mixing for a specified time. The manufacturer who offers high-speed mixing also provides a system that mixes to a certain amperage or energy level on the motor. This tells bakers when the dough has reached its proper development. This helps bakers who have flour that changes from season to season, the manufacturer says.
The manufacturer offering horizontal mixers also promotes variable frequency drives instead of a twospeed starter operation. The variable frequency drives allow bakers to change agitator rpm for a particular product. Bakers can run one product at a high speed, and another at a lower speed. This program also lets bakers ramp up and down at the beginning and ends of the agitation, which minimizes the shock load that the equipment experiences, the manufacturer says. This also minimizes the mixer's power spikes, which will reduce energy costs, he says.
Preventative maintenance programs also are available for mixers. These programs record how many hours that mixers have ran and alert bakers when inspections are necessary.
Mixing dough has never been more easy or advanced with today's technology. Continuous, high speed, horizontal and vertical mixers all offer bakers special features to ensure that the dough is mixed correctly. In addition, further advancements in technology improve dough development and maintenance.