I have copied a very informative article on how a mixing method effects the characteristics of a crust.The article is written for bread bakers however it has applications for pizza dough.The source is San Francisco Baking Institute Newsletter Summer 20007, Volume 2
This is “Part Two” of my article on
How to Develop a Formula. Please
see our Winter 2007 newsletter
for “Part One.”
Choosing a Mixing Technique
Three main mixing techniques are available
to the baker: short mix, intensive mix and
improved mix. Different fi nal product characteristics will be
obtained depending on the technique you choose.
A. Short Mix
Using the short mix technique, the mixing of the dough generally happens only in fi rst speed. Consequently, the gluten will be underdeveloped and a long fermentation time, with a few punch and folds, is required to achieve the proper strength necessary to shape and proof the dough. As a direct result of
this combination (short mixing and long fermentation time)
the bread will have very creamy color (very limited dough
oxidation keeps the carotenoid pigments intact), highly
complex fl avor (long fermentation time) and an open and
irregular crumb structure (short mixing time.)
Volume will be somewhat penalized since the underdeveloped
gluten won’t be able to retain as much gas during fi nal
proofi ng. This technique can be used when the characteristics
of a hand mix bread need to be duplicated. However, due
to the lengthy fermentation process and the underdeveloped
gluten (making machinability diffi cult) this technique is not
suitable for high volume production.
B. Intensive Mix
With the intensive mix method, the dough is mixed to its full development creating a perfectly organized gluten structure. Because the dough is already strong enough, fi rst fermentation time can be shortened, making the dough very suitable for high speed production. However, due to the long mixing time, the crumb of the bread will be whiter (more oxidation is created) and not as visually appealing. Because of the short fi rst fermentation time, it is preferable to use a preferment in the formula or the fl avor of the bread will be bland and the shelf life shortened. The intensive mix technique creates breads with larger volume, fi ne cell structure (due to the perfectly organized gluten structure, which allows for even gas distribution and expansion during proofi ng and baking) and thin crust. C. Improved Mix
A combination of the short and intensive mix process, improved
mix technique is probably the most common mixing technique
used in artisan baking. The dough is mixed to the point where the gluten reaches about 75%-80% of its full development, leaving some space for fermentation activity to take place to complement the strength of the dough. The shorter mixing
time (compared to intensive mix) preserves the creaminess
of the crumb and the necessary fermentation time allows
aroma production and good shelf life for the fi nished product.
continued from page 1
continued on page 4
The cell structure of the crumb will be open and irregular (not as much as with the short mix technique, but much more than with the intensive mix technique.) Because of the better gluten development during mixing, the improved mix technique achieves dough with good machinability properties. For optimum dough and bread characteristics, this method can also be complemented with the use of
D. Double Hydration Technique
The growing demand for breads that are moist and dense inside with large and open cell structure (such as Ciabatta) has triggered the development of the double hydration technique. “Ciabatta-style” bread characteristics are usually achieved by mixing highly hydrated and well developed soft dough. The mixing of this type of dough can be obtained using two techniques.
The first technique is to add all the water at once at the beginning of the mixing process, and mix the dough to complete development. But in this case, to obtain a well-developed gluten structure, the mixing must be sufficiently long, as the extra water will interfere with proper gluten formation. Another option is to keep the mixing time short and achieve dough development with a series of punch and fold.
The first option is not ideal for product quality since long mixing time generates a lot of oxidation (therefore, a loss of flavor) and the second option is not particularly suitable for high volume production since folding large amounts of dough is not very efficient.
The newer technique—double hydration—is to add the water two times into the dough. The main advantage of this process is to create very soft dough with well-developed gluten structure, great machinability properties and good strength, with minimum mixing time to avoid over-oxidation of the dough. First the dough is mixed with only a portion of the total water of the formula to reach a medium/soft consistency. Depending on the flour and the type of preferment used, the water proportion usually represents 60% to 70% of the flour in the final dough.
The goal is to properly hydrate the flour components without getting an excess of “free” water or water not fixed by any flour components. Molecules of free water impede gluten bonding and gluten structure formation, leading to longer mixing time and more dough oxidation. Once the medium/soft consistency has been reached, the dough is mixed to obtain an improved mix gluten structure. Then, the remaining part of the water is added and the mixing continues until the water is perfectly incorporated into the dough.
As with butter in brioche dough, properly developed gluten can very easily take an extra “load” of ingredients or water. The final result is a dough with a very soft consistency but not sticky, and a well-developed gluten
that won’t require any folding during the first fermentation time. However, because of the soft consistency, the dough after mixing has an excess of extensibility, and requires some fermentation time to reestablish a good balance in strength. Obviously, this fermentation time is a positive thing for the quality of the bread as some gas and acidity will be developed, improving the cell structure of the finished product as well as its flavor and shelf life. After the first fermentation, because of its strength and its property of not being sticky, the dough can be processed by hand, and also has the characteristics required to run perfectly through a stress-free dividing and molding line.
Once bakers have mastered these well- established mixing techniques, they can easily create their own mixing process according to the desired type of bread, the equipment available at the bakery, or production requirements.
For example, a compromise between short mix and improved mix technique could be developed. To achieve this, it becomes important to modify the formula. If the mixing time is reduced, the first fermentation time must be increased to complement the development of the gluten structure.
The growing demand for breads that are moist and dense inside with large and open cell structure (such as Ciabatta) has triggered the development of the double hydration technique.
continued from page 3
continued on page 5
At this point, it becomes necessary to decrease the amount of yeast in the formula to control the fermentation activity. Water content should also be increased to counter the fact that acidity increases strength and penalizes extensibility of the dough after the first fermentation. Starting with a well-hydrated dough, which is adequately extensible, is necessary or machinability will be penalized. The possibilities are endless, but the baker must keep in mind that formula and process are
very interconnected and should be balanced carefully.
How long should the first
The first fermentation time depends on the mixing technique used, and also on the type and proportion of preferment used in the formula. Intensive mixing generates dough with fully developed gluten structure. This type of technique is necessary when tight and even cell structure is required. As a result of the long mixing time, the dough is strong enough after mixing. Allowing the dough to ferment after mixing would add some strength (due to the acidity production) and might create dough very difficult to work with (lack of extensibility.) However, not having sufficient fermentation time will penalize flavor and shelf life. The only way to compensate is the use of preferment in the final dough.
Short mixing time will automatically require longer first fermentation time to achieve proper dough development. The carbon dioxide naturally generated during the first fermentation will stretch the gluten, while the acidity will reinforce the bounding of the structure. These two combined actions will improve the strength of the dough.
Some folds might be necessary if the gluten is deliberately left very underdeveloped at the end of mixing time. The folding will also improve the gluten structure by creating more bonds (a little bit like the hook of the mixer will do but in a much more gentle way.) The very positive aspect of having a long first fermentation is the aroma development and increase in shelf life. Both of these qualities are obtained by some specific acids developed during advanced stages of the fermentation time.
When a production process doesn’t allow much time for a long first fermentation, the formula must be modified. To avoid penalizing final product quality by shortening the first fermentation, the baker must do before mixing what can’t be done after: a portion of the flour is incorporated into a preferment to allow acidity production to happen before mixing. Once this portion of pre-fermented flour is returned to the final mix, it will bring most of the benefits of the fermentation (strength of the dough, flavor and shelf life.) First fermentation can then be reduced without compromising final product quality.
When formulating, very precise numbers are difficult to calculate, but as an average, involving 20% of the flour weight into a preferment could allow the baker to cut down his first fermentation from two hours to one hour. The amount of yeast would have to be adjusted in order to get the same amount of gas production.
The dough can also be placed at lower temperature (around 40°F to 50°F) after mixing. This technique allows the baker to delay the first fermentation time to accommodate production requirements. For example, the baker may mix the dough at the end of the production day and place it in the cooler until the next day. The dough is then ready to be divided as soon as the baker arrives at the bakery. This technique allows the baker to reduce night shift hours and still have some bread ready to bake early in the morning. The other advantage is that some of the dough can be divided first thing in the morning and the rest later in the day to offer fresh bread to customers without having to mix several times during the day. When using this technique, a very low amount of preferment is generally used in the formula.
The long first fermentation at low temperature naturally develops enough acidity to improve dough characteristics and bread qualities. Using too much preferment can negatively affect the gluten structure, as too much enzymatic activity and dough degradation can happen during the pre-fermentation process and the long first fermentation.
The possibilities are endless, but the baker must keep in mind that formula and process are very interconnected and should be balanced carefully.