Last fall I wrote about mixing for this column, and in that article we looked at the mixing process in a generalized sense: a basic overview from incorporation of ingredients to the final stages of dough development. In this column we are going to add some detail to that discussion, and will specifically examine mix times.
By way of some background we should quickly review the actual transformation that the dough is undergoing as it moves from a rough mixture of ingredients to a well-formed and cohesive dough. The proteins found in wheat that allow a cohesive dough to form and are capable of trapping the gases produced during yeast driven fermentation are the gluten forming proteins: gliadin and glutenin. As the flour particles are wetted and the action of the mixer beings to organize the protein strands the dough starts to develop strength as the sulfur units that protrude from the protein strands come in contact with one another and, through oxidation, form linkages known as di-sulfide bonds.
It has been determined that the gliadin proteins contribute to dough extensibility and that glutenin contributes to dough strength and elasticity. It should come as no surprise then that the relative ratio of gliadin to glutenin as found in various grains will have a direct affect on the overall dough characteristics. Bread wheat, on average, has a glutenin to gliadin ratio of 0.55 whereas spelt has a ration of 0.33. Anyone who has worked with 100% spelt dough will certainly recognize that those doughs do not exhibit the elasticity of a dough made from bread flour and that is because there are more gliadin (extensibility) proteins relative to glutenin (elasticity) proteins in spelt.
While the gliadin-glutenin ratio certainly contributes to the overall protein "quality" of a particular flour it is not a realistic measurement that a baker will have access to prior to working with a particular lot of flour. However, in terms of understanding the mixing characteristics of a particular flour prior to working with it there are two widely used analysis methods: the alveograph, and the farinograph. Here in the U.S., most of our flours are analyzed using the farinograph, whereas Europe and Latin American bakers tend to rely more on the alveograph. For this article we will use the farinograph since it is what most of us are likely to encounter on a daily basis.
There are several resources available for understanding the results of a farinograph analysis (including one I wrote for the 2008 Baking Buyer Basics of Baking issue, and I would suggest that, if you are interested, you seek one of those out as we will not have the space here for a thorough overview. For now, please look at figures 1 and 2. These represent farinograms for two different flours. Basically, a farinogram is a graphical representation of the amount of energy it takes to mix a dough from initial incorporation of the ingredients (the left side of the graph) through dough breakdown (the right side) with the optimum mix occurring where the graph is centered on the 500 BU (x-axis) line. The units along the bottom axis are time measured in minutes.
Just by looking at the farinograms you can see that these two flours exhibit different characteristics. We'll focus on just two characteristics of these flours as measured by the farinograph: development time and stability. The development time is the amount of time it took to mix the dough to full development. In the first flour example you can see that the dough mixed together relatively quickly and has a development time of 2 minutes. (A typical hi-gluten flour (14% protein), in contrast, might have a development time of 7 minutes: there is just more protein to organize.) The flour analyzed in the second farinogram has a slightly longer development time of 2.5 minutes. Here is the key thing to remember: you cannot use these as your mix times when mixing doughs in a production setting. These are the times that it took the farinograph to mix to an optimized dough strength, not a production mixer. The value of the farinograph, then, comes when you compare two (or more) farinograms relative to one another. From these two examples we can determine that the flour in figure 2 should take slightly longer to mix to development than the flour in figure 1.
The second characteristic we will look at is "stability." This is a relative measure of how long a dough can be mixed before the gluten network begins to breakdown resulting in an over-mixed dough. The two flours in our example show marked differences in their ability to handle increasing amounts of mix. The flour in figure 1 has a "stability" of 2.7 minutes whereas the flour in figure 2 has a "stability" of 11.6 minutes. This indicates that when mixing a dough using the first flour you have a much narrower "window" of time before the dough begins to breakdown and exhibit the characteristics of an over-mixed dough. Whereas the bottom flour has much more tolerance to continued mixing and will remain a relatively workable dough for some time past the point of initial full development.
Now we are narrowing in on the real challenge in mixing a dough: when do you stop the mixer. It is certainly not a trivial point, even though the flour in figure 2 would indicate that you could just "mix for awhile" and then stop and still be all right. The reason is that in most instances you do not want to mix to full development, especially if your doughs are going to have long fermentation times or undergo other strength building steps such as folds, or mechanical dividing and shaping.
Martin Phillip, a baker at King Arthur's Bakery in Norwich, Vermont told me, "that the level of mix (or, the amount of development) is completely variable by product. The only doughs that we look for a true “window pane” [full development] are brioche and Challah. Ciabatta also needs good development in order to support the high hydration, but I would say that as a general rule rather than adding mix time to achieve development we use an autolyse [a rest in the mixer bowl after the ingredients have been incorporated] and rely upon folds to give strength."
It is important to recognize that in addition to strength being built mechanically in the mixer and through folds during bulk fermentation, the dough will also continue to strengthen "chemically" over time due to the acidity of the dough. Therefore, if you mix to full development in the mixer, your dough can become too strong by the time you reach the later stages in the baking process. Michael Eggebrecht, Bakery Consultant and King Arthur Flour's Technical Support Advisor put it this way: "you either mix to full development or you ferment to full development," and your overall process determines which way you need to go.
Determining your mix times is largely gained through knowing the relative differences from flour lot to flour lot as indicated by the farinograph, and through the experience of working with your doughs all through your baking process. Once you have determined the optimum mix time for your various doughs you should stick to them. Again, Martin from the King Arthur Bakery: "...we never mix anything without a timer running. Bakeries running relatively standard batch sizes should be able to quantify the needs of their dough and the necessary amount of mix time." Consistent mix times, adjusted slightly for differences due to changes in the flour, are going to allow you to mix the dough to same stage of development each time giving your dough a consistency which not only helps your bakers further along during the baking process but also will allows you to deliver consistent products to your customers.
Figure 1: protein: 10.91%, ash: 0.527%, Development time: 2.0 min, Stability: 2.7 min.
Figure 2: protein: 12.10, ash: 0.476, development time: 2.5 min, stability: 11.6 min.
World’s Fair of Bread
The Bread Bakers Guild of America will sponsor a tour of Heartland Mill, a pioneering organic flour mill in Marienthal, Kansas, on April 26 to educate bakers about how wheat varieties are selected and bred and how the wheat is processed into flour.
The Kansas Mill and Farm Tour is the first of three mill tours taking place around the country this year as part of The Guild’s World’s Fair of Breads 2010.
Attendees will have the opportunity to walk through the milling operation and visit the quality control laboratory. They will watch demonstrations of the Alveograph and other apparatus and learn how to interpret test results and apply this knowledge in the bakeshop.
Tour leaders will be Thomas Leonard, former Guild Board member and founding partner of WheatFields Bakery Café in Lawrence, Kansas, and Mark Nightengale, co-founder and General Manager of Heartland Mill. The all-day event will also include tours of local wheat farms and a presentation by Stephen Baenziger and Richard Little from the organic wheat-breeding program at the University of Nebraska
Leonard says, “I’m excited about being able to share with fellow bakers some of what I love about western Kansas – the uninterrupted views to the horizon in all directions, shortgrass prairie, grazing bison and pronghorn, the distant grain elevators marking the next town, 10 or 15 miles down the road. This is a great opportunity for bakers to learn more about their single most important ingredient, and there’s no better place to get it than the High Plains of western Kansas.”
Heartland Mill is a farmer-owned company dedicated to developing ethical partnerships with organic farmers. For more information about the mill, visit www.heartlandmill.com.
In other events from the World’s Fair of Breads 2010, The Bread Bakers Guild of America plans the following:
May 15-16 – Traditional Italian Holiday Baking in Providence, RI
June 5-6 – Indian Bread Craft in San Francisco and Oakland, CA
June 19-20 – Introduction to Artisan Bread in South San Francisco
July 9-10 – Breads from the Wood-Fired Oven in Norwich, VT
For more information on these events, visit The Guild online at www.bbga.org.
The Guild on April 9-10 presented a sold-out baking education class on rye breads taught by Master Baker Jeffrey Hamelman as part of its 2010 Master Class series, The World’s Fair of Bread, which spotlights international breads.
“Rye breads have always enjoyed a special significance in northern and eastern Europe,” notes Hamelman. “Knowing and understanding rye’s unique requirements is the key to being able to produce rye bread with its rich aroma and unique flavor.”
The class on rye breads was held at the King Arthur Flour Company’s Baking Education Center in Norwich, VT. The lecture and hands-on class, aimed at beginning and intermediate bakers, covered all aspects of rye bread production, including sourdough rye culture, mixing techniques, fermentation, and steaming. The characteristics of rye flour, which produce results quite different than those of wheat flour, were also a focus.
Hamelman is a Certified Master Baker, the highest rank available to American bakers, and has over 30 years of experience baking sourdough rye breads. He was a member of Bread Bakers Guild Team USA 1996 and coached the 2008 team. The author of the highly acclaimed Bread: A Baker's Book of Techniques and Recipes, he is a past recipient of The Guild’s Golden Baguette Award (now the Raymond Calvel Award), which recognizes individuals who have contributed significantly to the advancement of artisan baking. He is an employee-owner at King Arthur Flour, where he directs the production bakery and teaches professional level classes in the King Arthur Baking Education Center.
The King Arthur Flour Company is America’s oldest flour company, founded in 1790. Today it is an employee-owned, open-book, team-managed company. Education is a significant part of its mission.