What is Dough Fermentation
Dough fermentation involves much more than simply allowing dough to “rise” during fermentation. It involves the interaction of yeast, temperature, time, hydration, strength, acidification, and gas retention of the dough. This guide describes major challenges involving dough fermentation and controlling the dough fermentation process in a bakery or during food production.
Dough fermentation means yeast has time to consume fermentable sugars and produce various carbon dioxide and ethanol, flavor compounds, and various metabolic by-products.
The trapped carbon dioxide created from yeast fermentation serves an important function within the gluten network. It causes dough to expand and creates gas cells that ultimately determine the volume of the final product and the crumb structure.
Bread fermentation can be expressed by the following equation:
Yeast + Sugars → CO2 + Ethanol + Flavorings
In the end, carbon dioxide is by far the most important of these compounds, as the gas produces the gas cells responsible for volume and the crumb structure of the bread.
Fermentation involves more than gas production, as the dough undergoes changes such as:
- Gluten structure
- Dough extensibility
- Dough elasticity
- Dough acidity
- Availability of sugars
- Enzyme activity
- Dough temperature
- Gas cell distribution
Why Dough Fermentation is Important?
Dough Fermentation is an important process in bread making, since it governs the ability of the dough to develop gas, flavor, structure, and the property of the Final dough to a considerable extent. Fermentation is the process of the conversion of sugars to C02 by the action of yeast. The gluten network traps the gas to allow the dough to expand carbon dioxide or fermentation.
Fermentation that is too rapid, too slow, or too long can affect an upset in the proper formulation balance and lead to poor loaf volume and undesirable crumb, weak dough, poor oven spring, consistently poor baking conditions, and reduced product quality.
The goal of fermentation control is not into fermentation as much as possible. The objective of fermentation control is to stop the fermentation process at the desired point.
Under-Fermentation
Under-fermentation is caused by insufficient time for fermentation to occur, low dough temperature, inadequate yeast activity, too much salt or sugar, characteristics of the flour that are not suitable, and process conditions that limit activity of the yeast. An under-fermented dough has not generated sufficient C02 and has not undergone the necessary structural changes. As a result, it proceeds to the next stages of processing (dividing, shaping, proofing, and/or baking stages) while still under-fermented.
One of the most obvious effects of under-fermentation is low bread volume.
During normal fermentation, yeast produces CO2 gas. The gas becomes trapped as the dough expands. If there is insufficient fermentation, little gas is produced before the dough reaches the shaping or baking stages. This means the gas is trapped within small volumes.
The result is a
- compact dough
- small gas cells
- dense bread
- underdeveloped volume.
Compact dough can result from a number of causes including insufficient fermentation or weak gluten. Because it is not possible to tell which of these caused the low volume, it is prudent to investigate both.
A number of reasons can cause low volume. Of these common reasons, undermixed dough and insufficient proofing is the most prevalent.
- Fermentation time is too short
- Dough temperature is too low
- Weak or inactive yeast
- Excess salt
- High sugar concentration
- Poor flour quality
- Incorrect mixing
- Poor proofing conditions
Control finally dough temperature, fermentation time, yeast condition, and proofing conditions and do not simply increase yeast.
Dense crumb can also be attributed to multiple causes. Other factors including insufficient mixing, poor shaping, excessive dusting, and poor proofing can produce dense crumbs.
- Control
- Evaluate fermentation along with:
- Dough temperature
- Mixing development
- Proofing time
- Flour strength
- Hydration
- Yeast activity
Poor Gas Cell-Development
The development of gas cells within the dough is critical to the final shape of bread.
When the yeast produces carbon dioxide during fermentation, the gas forms immensely tiny bubbles, which explode and join together and distribute themselves throughout the dough.
This development can become limited.
The dough will contain:
- Too small of gas cells
- Gas cells of an ununiform size
- Undeveloped internal dough structure
- A tight crumb
In order to develop gas cells of sufficient size and be able to hold the proper gas, adequate fermentation and gluten development is required.
Control
To improve gas cell development:
- Maintain the proper temperature of the dough.
- Adequate yeast activity.
- Time for appropriate fermentation.
- Gluten development.
- Limit mechanical work after fermentation.
- Final proofing.
Tight Texture
Excessive elastic resistance of a dough often occurs when the needed degree of relaxation of the structure due to fermentation does not take place.
This may result in:
- A compact texture
- Firm crumb
- Poorly developed extensibility
- Inferior eating qualities
Texture is a multiple variable system and may be due to protein of the flour, degree of hydration, added fats, sugars, extent of mixing, baking conditions and how the bread is cooled. Fermentation is one important variable of the system.
Control
During fermentation, the dough should be continuously tested to determine the extent of development and for complete, even expansion, prior to progressing to the next step.
Pale or Uneven Crust
Inadequate fermentation can lead to issues with crust characteristics.
The length and type of sugars undergoing fermentation determine the reaction sugars available for baking. Some sugars are fermented by the yeast. The balance of sugar reactions and residual sugars helps determine crust color.
If the dough is significantly under-fermented, the loaf can have:
- Pale color
- Uneven browning
- Poor surface development
- Unusual crust characteristics
However, the appearance of the crust can be attributed to:
- How the dough is formulated.
- Oven temperature
- Baking time
- Sugar (including milk solids)
- Egg
- Surfacing of the bread
- Baking humidity
So, a pale crust may not be attributed to fermentation. It is most likely a process issue.
Reduced Flavor
Sufficient fermentation is necessary for the development of bread flavor.
Besides producing carbon dioxide, yeast fermentation provides many other metabolic products that substantially contribute to the formation of the taste and aroma of the bread.
Short fermentation times can result in:
- Limited aroma development
- A simple flavor
- Lack of the characteristic flavor of bread
- Unbalance of fermentation products
Longer fermentation can increase flavor development, but very long times can result in further undesirable changes in the quality of bread.
Excessive Elasticity
Under-fermented dough is too elastic.
Under-fermented dough presents an immature gluten structure which is quick to snap back.
In the processing route, this causes:
- Resistance to rolling
- Resistance to sheeting
- Shrinkage after shaping
- Resistance during molding
- Poor hold in the application
The tendency is for the dough to become ‘tight’ or ‘young’.
Most of the time under fermented dough is elastic. A tight structure exhibits resistance to growth.
Difficult Shaping
Under fermented dough is difficult to shape because:
- Resist stretching
- Spring back
- Tear during stretching
- Requires higher process pressure
- Poor holding shape easily during processing
- There is increase in processing variation.
This is particularly important for industrial bakeries, since dough has to continually move through:
- Dividers
- Rounders
- Intermediate Proofers
- Molders
- Sheeters
- Depositors
- Not fully fermented dough causes issues throughout production.
Control
Check if the dough has relaxed and fermented. Also, check if the mixing conditions and flour strength work with and support the intended process.
Gas production can continue even as the dough begins to show other signs of structural evolution. The gluten network can become ineffective in gas retention.
Over-Fermentation
Some of the causes of over-fermentation are:
- Longer than optimal fermentation time
- High fermentation temperature
- Excessive yeast activity
- Delayed processing
- Suboptimal proofing conditions
- Bad production scheduling
The combination of a number of these causes can be very problematic.
One of the signs of over-fermentation is over-softening of the dough.
Over-softened dough may feel:
- Weak
- Loose
- Lacking in resilience
- Being difficult to control
- More stretchable than it ought to be
This can make it difficult to process mechanically.
Softness, however, doesn’t always mean over-fermentation. There are other factors like the strength of the flour, mixing, the hydration level, and enzymatic activity.
Control dough temperature and the fermentation time. Adjust the time accordingly if the dough temperature drifts out of normal operating range, as advised in the production procedures that have been validated.
Sticky Dough
Over-fermentation changes the physical state of the dough structure. Gluten can lose strength, causing the dough to break down and lose cohesion.
Operators may notice:
- Sticking of dough to equipment
- Difficult dividing
- Difficult molding
- Excess use of dusting flour
- Lack of shape retention
- Irregularity of pieces
Stickiness that is out of control can also be due to overhydration, weak flour, high enzyme action, and incorrect ingredient addition.
Therefore, over-fermentation has to be considered with these other factors.
Weak Dough
Increased fermentation causes a loss of dough strength and is one of the most important decadent effects on dough.
Dough strength is important in order for dough to:
- Hold carbon dioxide
- Maintain its shape
- Survive mechanical handling
- Expand during proofing
- Endure oven expansion
If the fermentation is excessive, the dough loses strength.
Events such as poor shape retention and tearing may occur. It may also become very difficult to lift, transfer or hold individual pieces. The dough may become very soft, extensible, sticky and weak.
Many problems may be attributed to the effects of weak dough in a commercial bakery. First, it can create variations in product quality and consistency. Second, defective product may result in production loss and increase the amount of defective product needing to be discarded.
Difficult to Handle
Many problems occur in both machinery and the bakers when over-fermentation results in dough that is too soft, sticky and very weak.
Dough that is too extensible and soft makes molding and shaping difficult.
There are a number of ways that both the machinery and the workers will respond to deal with the excessively soft and sticky dough. Workers may add excessive dusting flour. The machinery may become more aggressive in order to apply mechanical pressure to the dough.
A better solution is more dough control during fermentation rather than responding to changes during dough processing.
Difficult to Shape
Under-fermentation results in too much dough elasticity. Over-fermentation results in the opposite. Over-fermented dough lacks strength to hold its shape during shaping.
Shaping over-fermented dough results in various problems.
The dough shape may tear. The dough shape may lose its tension. The dough may collapse and lose its uniformity.
This is a greater issue when shaping products like bread, buns and rolls, baguettes, or any product that requires shaping with uniformity.
Control
Minimizing delays between dividing, shaping, and baking reduces excess fermentation.
Prone to Collapse
An over fermented dough may have a lot of gas, but as the gas builds, the integrity of the structure begins to break down.
Gas cells may develop an unstable structure with poor support.
This can result in the complete breakdown of the structure either during handling or while baking.
The final result can be a bread with
- Low volume,
- Irregular crumb,
- Flattened shape,
- Large irregular holes
- Weak internal structure.
The breakdown of the structure happens during all stages of the process including proofing, scoring, transfer of the loaves to the baking surface, and during baking.
So rather than allowing the dough to ferment as much as possible, it is important to control the fermentation to the required extent.
Over Acidic in Some Fermentation Systems
The degree of acidity affects the outcome of the process when dealing with long fermentation processes like sourdough.
During the fermentation process, the sourdough microorganisms produce lactic and other organic acids. The degree of acidity produced depends on the following factors:
- Population of microorganisms,
- Temperature,
- Length of time,
- Type of starter,
- Hydration,
- Flour
Poorly controlled acidity affects the following:
- Flavor
- Aroma
- Dough strength
- Characteristics of the crumb
- Overall product quality
This however does not mean that acidity should be avoided. Controlled acidity is a desired attribute in the final product of sourdough.
Over control produces an undesired final product of sourdough.
Poor Oven Spring
Oven spring describes the large expansion that occurs when the dough enters the oven.
This expansion is caused by several factors like:
- Vaporization of existing moisture
- Increase in pressure of the gas
- Formation of water vapor
- Early activity of the yeast
- Structure of the dough
Dough that has been over-fermented may have poor structure and will not benefit from expansion.
As a result, a loaf may show:
- Limited oven spring
- Short height
- Flat profile
- Poor scoring
- Irregular shape
Prior to baking, bread may appear large but will not be able to achieve desired final structure.
Elements Affecting the Process of Dough Fermentation
Several variables impact the process of fermentation simultaneously.
The most significant of these are the following:
- Temperature of the dough
- Duration of the fermentation process
- Number of yeast cells and their activity level
- Quality of the flour
- Level of water
- Concentration of salt
- Concentration of sugar
- Level of acidity of the dough
- Strength of the dough
- Environment of fermentation
- Conditions of dough mixing
- Size of the dough
- Use of sourdough or preferments
- Type of equipment
- Conditions of handling and proofing
Understanding the above will help develop reliable control systems of the process of dough fermentation.
Control of Fermentation During the Summer
This is an area where we deal with the greatest challenges.
Things we must do include the following:
- Check temperature of flour.
- Check temperature of the room.
- Use cool mixing water.
- Monitor temperature of newly mixed dough.
- Avoid holding mixed dough more than required.
- Check conditions of proofing.
- Control yeast storage.
- Do not expose dough to hot production areas.
- Keep in mind the need to avoid uncontrolled temperature rises.
- Control of Fermentation During the Winter
- During this time use warm mixing water.
- Avoid overly cold flour.
- Check final dough temperature.
- Keep proofing conditions under control.
- Do not rely on long extended fermentation times.
If the fermentation process slows down, investigate the reason before increasing the amount of yeast.
Control of Fermentation Using Data
In order to improve control of the process recording the various process data is essential.
For every batch, include the following:
- Date
- Product
- Flour lot
- Flour temp
- Water temp
- Yeast lot
- Yeast amount
- Mix time
- Final dough temp
- Bulk fermentation time
- Proof temp
- Proof humidity
- Final proof time
- Oven conditions
- Final bread volume
- Product defects
After several weeks, you can see trends.
The bakery may notice that loaf volume decreases with lower dough temperatures, or that a certain flour lot requires a specific fermentation schedule.
This shifts the control of fermentation management from the subjective judgment of the operator to a measurable process control system.
HACCP and Fermentation
As with any other process, fermentation should have controls built into the safety system.
Fermentation, although a quality system control process, can affect the behavior of microorganisms with the application of time and temperature.
Therefore, the bakery should establish procedures for:
- Hygiene
- Equipment sanitation
- Ingredient controls
- Temperature controls
- Holding time limits
- Cleaning
- Documentation
Staff Training
An excellent fermentation system can still fail unless operators are trained.
Operators need to know:
- The effects of dough temperature
- How to measure dough temperature
- Signs of under-fermentation
- Signs of over-fermentation
- How to control proofing
- How to capture differences
- When to report to a supervisor
Operators should not be permitted to make large, unrecorded adjustments to yeast, water, fermentation time, or temperature.
Changes need to be made following a controlled process.