When exploring the philosophy of mixing, it’s natural to debate what’s right and wrong or what works and what doesn’t. Put five veteran bakers on the production floor, and they can spend hours listing all the pros and cons about why they recommend one method of mixing instead of another.
Take, for example, the classic discussion over straight dough vs. the traditional sponge-and-dough process. For several practical reasons, many bakers lean toward straight doughs because the process significantly decreases footprint and investment in mixing and dough handling equipment, especially when it comes to making conventional bread and rolls, said Marc Ferree, sales engineer, Shaffer Mixers, a Bundy Baking Solution.
“The straight dough process also eliminates the sponge fermentation time, which gives the baker more control over the process,” he said. “The elapsed time from the start of mixing to dividing the first dough piece is measured in minutes, not hours.”
Regarding special design needs for the different systems, the sponge-and-dough process may require special modifications to the equipment. Mr. Ferree explained that advances in PLCs also allow mixers to interface directly with ingredient systems to automatically feed the exact amount at the correct time. In addition, the entire mixing cycle, including agitator speed changes, can be pre-programmed and stored for multiple formulas. The mixer can also be programmed to discharge dough automatically.
“This decreases the amount of human interface required in the mixing process,” Mr. Ferree said.
Despite straight dough’s time efficiency, bakers are reconsidering traditional methods of mixing because of clean label trends.
“In bread, a long fermentation time in a sponge-and-dough process can help achieve this,” noted Bobby Martin, executive product manager, AMF Bakery Systems. “The artisan baker’s techniques to produce flavorful sponges can migrate to the industry by using a sponge-and-dough process through a fermentation room and floor time process. AMF’s newest fully automated fermentation room design offers the ability to run different floor times for each individual sponge, therefore offering the flexibility required in artisan-style bread production.”
Other consumer trends are piquing interest.
“With overall bread unit sales heading downward because of Atkins, keto and other diets, bakers are all struggling to offer something different to create more enthusiasm about bread,” said Damian Morabito, president and chief executive officer, Topos Mondial. “They’re looking at specialty breads or organic items that are perceived as being healthier and boost consumption and sales. We’re seeing the trend toward older-style breads as bakers embrace a more natural process.”
The great debate
Mixing philosophies also vary geographically. Consider the age-old wrangling over North American vs. European-style methods. In reality, the argument has more to do about product preferences than the debate of different technologies.
“North American consumers are buying sandwich loaves or burger buns and expect days, if not weeks, of shelf life,” observed Rick Kesig, business unit technical advisor, Peerless Food Equipment. “Conversely, European consumers purchase more artisan products, which are fresher but have a shorter shelf life.”
From a mixing perspective, he added, Europeans rely on the more traditional two-step process with a larger array of starters and longer rest times before adding the sponge during the final mix.
While time and temperature remain the most universally monitored variables, many other inter-related factors play a critical role in going from formulas to final products.
“This not only changes the flavor profile but also produces a harder crust formation and a greater open-crumb structure,” Mr. Kesig said. “This is typical of a sourdough and can be incorporated by North American bakers when making artisan products.”
A number of additional factors are at the heart of this ongoing discourse. In America, Mr. Morabito noted, no-time doughs rely on additives to go directly from the mixer to the divider.
“They use oxidizers, dough conditioners and maturing agents to get the floor time that European bakers achieve naturally through fermentation and resting,” he said.
That’s why removable-bowl spiral mixers remain popular overseas.
“It’s common to sell a mixer with 8 to 10 bowls because bakers are going to make a dough and let it rest,” Mr. Morabito explained.
For bread and rolls, perhaps the most glaring difference involves U.S. preferences for horizontal vs. Europe’s penchant for spiral mixers.
“Horizontal mixing systems make sense for some products such as toast bread, burger buns and other products that need a very fine cell structure,” said Patricia Kennedy, president, WP Bakery Group USA. “But for most other dough types, it is important to have a very good, even, dough development and dough structure.”
Spirals, Ms. Kennedy added, allow for enhanced oxygenation and gluten development that can add flexibility and control of downstream production processes. Moreover, in semi-automated bakeries, bakers can easily dump in chocolate flakes or raisins during the end of the mixing process.
“Both processes are great,” Mr. Morabito said. “Both work well. It’s just a preference. The horizontal 3-roller bar mixers are heavier duty for large industrial plants, so they are more reliable for higher throughput production needs.”
A continuous discussion
While time and temperature remain the most universally monitored variables, many other inter-related factors play a critical role in going from formulas to final products. That’s why many bakeries house multiple mixers ranging from spiral and horizontal to continuous mixers outfitted with prehydration systems.
“Overall, there’s more openness to using a different mixing technology and tailoring it to the product,” said John Hunter, sales account manager, bakery and ingredient handling, Bühler. “Bakers are now exploring multiple mixing processes because of greater diversity of the product.”
Several bakeries also consider continuous mixing for bread, buns and rolls.
“They are looking to find solutions that give more process consistency in their baking lines,” Mr. Hunter said. “The latest continuous mixing solutions include functionality such as applying a vacuum during the dough development process to deliver a fully developed dough to the process line.”
Joe Cross, engineering and process manager, Zeppelin Systems USA, pointed out that bread and bun producers have long been driven by consistency, value and volume.
“While continuous mixers have delivered on the first two from the very beginning, it has only been in recent years that mixing and metering technologies have grown to support the volume of large, fully automated bread and roll lines,” he said.
In the United States, Mr. Cross added, continuous mixers began their climb to acceptance through the snack manufacturing industry, starting with long-shelf-life items such as pretzels and fabricated potato snacks.
“In Europe, though, Zeppelin’s CODOS mixers were making fresh items such as bread and rolls from the very beginning,” he said. “Now, the oldest and best-established manufacturers have hundreds of installed systems worldwide, ranging from toast bread to cookies, croissants to hard pretzels, and pizza crusts to donuts.”
Mr. Martin observed that going from batch mixing to continuous on hamburger bun production offers challenges from a formula standpoint.
“That is why AMF leverages the expertise of Reading Bakery Systems (RBS), also a Markel Food Group company, to support bakers considering such a change,” he said.
Jim Warren, vice-president of Exact Mixing at RBS, noted that most snack doughs are developed from one-stage mixing.
“You pour everything into the system and mix it,” he said. “For the highly developed doughs, you have to first form the dough and do the development in a separate step because it’s a different type of process.”
For bread and buns, RBS developed the HDX continuous mixer, which now has throughput exceeding 15,000 lbs an hour. Additionally, the bread mixer sometimes operates more than 200 rpm to develop bread and bun dough, or about four times faster than it operates for pretzel and snack doughs.
“It’s the bread and bun industry that requires these higher and faster rates,” Mr. Warren explained. “Because bread dough is more developed, it requires much more energy input. The mixers had to be much more efficient in mixing.”
With fillings, icings and batters for sweet goods and desserts, continuous mixing has led to reduced labor while improving accuracy and greater repeatability, said Bob Peck, vice-president of engineering, ET Oakes.
For a cleaner label, he added, continuous mix aeration can reduce the need for emulsifiers by more than half in most applications.
“Complete elimination of emulsifiers may be possible with most varieties of cake batter,” Mr. Peck said. “It is also suggested that baking powder be reduced to approximately 75% of the amount formerly employed. Leavening agents can also be reduced, resulting in lower ingredient costs.”
Philosophy of formulas
When exploring different mixing processes, should the baker tweak the formula or adapt the technology to create new products or more consistent existing ones? Not surprisingly, there’s more than one answer.
“The formula does not have to change at all,” said Rich Breeswine, president and c.e.o., Koenig Bakery Systems. “It should be every manufacturer’s goal to adapt the equipment to the formula, not the other way around. The mixing times might vary, but the formula of a product should never change as this is the unique feature of each bakery.”
Koenig recently has focused its initiatives on how mixing impacts dough handling and final products. Sanitary design has been a key driver as well.
“Mixing is not an isolated process,” Mr. Breeswine asserted. “It is one important step in the production of high-quality bread and rolls. The customer advises Koenig on the desired end product and conditions in the bakery, and Koenig gives recommendations about the type of mixer, temperature of ingredients, mixing time, resting time and other variables to have the optimized dough to process it in subsequent steps.”
On the other hand, Terry Bartsch, president and c.e.o., VMI North America, suggested that some changes in certain formulas might be considered when evaluating mixing processes.
“Whether it is the type of flour or yeast, or the use of eggs, butter and other inclusions, each specific ingredient affects all phases of the product’s gluten network,” he said.
Other factors such as ingredient blending, hydration, energy transfer and aeration should be examined. It doesn’t matter if it’s continuous, batch, horizontal, vertical, spiral, fork or double-tool mixers, all which VMI makes.
“Depending on the required product, the type of kneader will act more or less on different aspects of the mixing: shear, extension, compression, aeration and energy transfer,” Mr. Bartsch said. “The mechanisms involved will have an impact on the texture of the final dough, including its stickiness, elasticity, firmness and extensibility.”
VMI is collaborating with ONIRIS University in France to develop more scientifically effective ways to identify, record and analyze key performance parameters to quantify which ones are optimal for producing specific baked foods. While mixers must adapt to a baker’s formula, it is possible to further improve some products by adjusting the salt or sugar levels, for example, to a specific process. Mr. Bartsch said such research at VMI’s Process Development Center may help bakers produce baked goods with a cleaner label and even longer shelf life.
Game on for fermentation
When it comes to sourdough, starters, sponges and fermentation, the playbook is totally different in Europe than in North America. In Europe, Mr. Hunter explained, a sponge or preferment is a liquid, free-flowing dough with a 50-50 ratio of water and flour that’s often fermented for hours before mixing. In North America, the solid sponge developed in a smaller horizontal mixer with flour, yeast and minor ingredients ferments in a bowl or trough for a few hours before it’s dumped into a second, larger horizontal mixer with more flour, water and other ingredients to create the dough.
“People are talking more about that process in the U.S. than they were a few years ago,” noted Kevin Knott, technical sales manager, Franz Haas Machinery of America, a division of Bühler. “Part of it comes from making more European-style breads, but it’s also from bakers wanting improved hydration of ingredients before they enter the mixer to create a more efficient process and, ultimately, more consistent and flavorful breads and rolls.”
Mr. Bartsch pointed out that adding preferments increases the dough preparation and undeniably makes the mixing process more complex.
Despite straight dough’s time efficiency, bakers are reconsidering traditional methods of mixing because of clean label trends.
“To carry out these processes in a repeatable way, automation and process programming are key to the success of a fermentation-based recipe,” he said.
The use of buffer tanks for these fermentation steps, automatically managed by a monitoring system, makes it possible to implement batch technology to enable flexible and scalable processes, Mr. Bartsch added.
European bakers have built automated floor time into the process, said Mr. Morabito. Such systems may include multiple bowls in a carousel or rack system, which automatically adds the bowls to a mixer when needed.
“You can automate the floor time either using a trough or bowl, or a dough handling belt system, which takes up less floor space by using vertical space,” he said.
Hydrating before mixing
One of the more talked about developments involves prehydration.
“It’s the next step in mixing technology,” Mr. Warren said. “Prehydration is the process of bringing liquids and dry ingredients together at the individual particle level, which results in near instant hydration.”
Mr. Hunter listed such benefits as increased water absorption, dough softness, loaf volume and longer shelf life as well as reduced fermentation time, mixing times, energy usage and microbial growth.
Bühler’s JetMix system delivers hydrated ingredients directly to the mixer with throughputs of more than 7 tonnes, or 15,000 lbs per hour.
Typically, Mr. Warren said, a prehydrator is physically small and attached directly to a continuous mixer.
“Prehydrators can also be used in conjunction with batch processes but must be explored on a case-by-case basis,” he said.
Many bakers are collaborating with mixing companies to incorporate prehydrators, such as RBS’ Hydrobond, with a variety of industrial-sized batch mixers.
WP Kemper and Zeppelin Systems partnered last year to create the KROMix system, a combination of Zeppelin’s Dymomix prehydration system and WP’s Kronos spiral mixer. Ms. Kennedy noted KROMix reduces mixing time by up to 40% while bakers can add up to 2% to 10% more water to the dough without affecting the process.
For students of mixing philosophy, there are many schools of thought while new advances in technology are adding to the debate. For bakers, it all comes down to freedom of choice and keeping an open mind to determine which methods are best for them in the long run.
