When it comes to the impact of heat in the mixer, hydration has a lot to do with it.
“Generally, higher hydration level doughs are mixed at lower temperatures because the flour is more willing to absorb water at lower temperatures,” said Jim Warren, vice president, Exact Mixing, Reading Bakery Systems.
Additionally, warmer ingredients don’t hydrate as well as the cooler ones, and that can impact mixing.
“More energy is required to hydrate these ingredients,” he said. “But the additional mixing only heats the dough more, which makes the ingredients all the more difficult to hydrate.”
Mr. Warren calls this the “heat of hydration.”
In batch mixing, sponge-and-dough products pose a particular challenge in the mixer.
With a 60% sponge, for example, that portion of the dough enters the final mixer at around 78°F to 80°F, and the flour coming in is around 100°F.
“You’re not getting much help in that final mixing stage to cool the dough when a large amount of the ingredients enter the mixer at 78°F,” said Terry Bartsch, executive product manager, dough systems, AMF Bakery Systems. “You’re targeting a 78°F final dough, and you still have to put mechanical energy into it; that’s challenging, especially in the summertime.”
A good rule of thumb is the higher the hydration of the dough, the cooler it needs to be. One example is English muffin dough, which is inherently sticky, even at its optimum temperature. For this batter-like dough, a baker looking for a final dough temperature between 62 and 66°F.
Dough development also comes into play, according to Joe Cross, engineering and process manager, Zeppelin Systems USA.
“Less developed dough has a little bit greater range of forgiveness than a more highly developed dough like for a sandwich bread or hamburger bun,” he said. “Those doughs have a narrower operating range to get a higher quality product.”
In many cases, pre-hydration can reduce mixing time, which will naturally help control temperature. Zeppelin’s Dymomix technology achieves this.
“We’re pre-hydrating the flour — and all pre-blended dry ingredients — and we’re adding water, yeast and other liquid ingredients. By pre-hydrating efficiently, we significantly reduce the overall mix time, which lowers the friction that manifests itself as heat.”
When bakers are working with equipment manufacturers on mixer design, they should be sure to consider the product type and hydration needs when configuring the tools for temperature control.
This article is an excerpt from the September 2020 issue of Baking & Snack. To read the entire feature on mixing, click here.