Pre-feed rollers between the hopper and compression head can improve the consistency of dough flow, which keeps production moving. Source: Reading Bakery Systems

The key to efficiency
Consistency — in fillings and doughs — is vital not just in final product quality but also in processing efficiently and safely. Dough hydration and filling temperature affect how smoothly product is extruded.

Some fillings, such as meats and cheeses, need to be stored at colder temperatures, but those temperatures make them more difficult to extrude.

“When cheese is at 70°F it’s soft, but when it’s at 35°F, it’s near that freezing point, and it becomes hard and stiff,” Mr. Zelaya said. Stiffer fillings require more power to pump and extrude the material.

“Handtmann has some forming systems that can handle stiffer or cold fillings in combination with hard, soft or sticky doughs and smoothly combine a coextruded pretzel,” he continued.

The Vemag from Reiser can also portion fillings and doughs from a wide range of viscosities, including cold and stiff cheeses.

Consistency is especially vital for yeast-raised doughs. Yeast, being an active ingredient, changes the dough continuously once it is activated.

“The viscosity of the dough is changing due to the addition of carbon dioxide gas generated during early fermentation stage,” Mr. Eshelman said. “It’s going to make the dough spongier and less dense. If you extrude that gassy dough, it’s going to extrude at a different rate than that of a dough with lower levels of yeast or no yeast at all, which would result in a higher density dough.”

Between the hopper and the compression head on RBS’s Filled Stick Extrusion System, pretzel producers can add powered pre-feed rollers to increase dough flow consistency. These counter-rotating rollers force feed the dough from the hopper into the main augers for extrusion.

“There’s a lot going on inside that chamber,” Mr. Eshelman said. “It’s impeding the dough flow. It can get congested inside the machine, and these pre-feed rollers meter the dough and make the dough flow far more consistently.”

Achieving the most consistent bake, however, requires not only the proper dough-to-filling ratio but also the proper shape choices. For example, if the dough jacket is an oval, but the filling is extruded in a round shape, the thickness of the dough jacket will be inconsistent.

“You’re going to have a heavy mass of dough on the top or bottom and very little mass on the opposite side,” Mr. Eshelman explained. “That lower mass of dough is going to bake much faster than the heavier mass, and that’s where you start to burn, blister or have blowouts.” Matching the filling shape to the dough jacket shape is an easy way to avoid this issue.