Proteases in Food Processing: Types, Functions, Applications and Role in Cereal Fermentation

By GIFSQ | Published August 12, 2026

Proteases in food processing are enzymes that hydrolyze proteins into smaller peptides and, with further enzymatic action, amino acids. They are important in cereal processing, baking, fermentation, brewing, protein hydrolysis, meat processing, and other food applications.

Cereal grains naturally contain proteases and peptidases. In mature, sound cereals, their activity is generally relatively low. During germination, fermentation, and food processing, proteolytic reactions can become more significant and influence protein structure, peptide formation, soluble nitrogen, dough properties, and fermentation performance.

In wheat-based systems, endogenous cereal proteases and microbial peptidases contribute to the breakdown of cereal proteins during fermentation. Research on sourdough shows that proteolysis can affect bread flavour, volume, and texture and that acidification can increase the activity of cereal proteases and improve substrate accessibility.

What Are Proteases?

Proteases are enzymes that hydrolyze peptide bonds in proteins.

A simplified reaction is:

Protein → Protease → Peptides → Smaller peptides → Amino acids

Proteolysis does not occur as one single reaction. Different enzymes can act at different stages of protein degradation.

Proteinases

Proteinases, also called endoproteases, hydrolyze peptide bonds within protein chains.

Their action can reduce larger proteins into smaller peptide fragments.

Peptidases

Peptidases hydrolyze peptide bonds in smaller peptide substrates and can contribute to the formation of still smaller peptides and amino acids.

A useful simplified sequence is:

Protein → Proteinase → Peptides → Peptidase → Smaller peptides + Amino acids

This distinction is particularly useful when discussing cereal fermentation.

Proteases in Cereals

Mature, sound cereal grains contain endogenous proteases and peptidases, but their activity is generally relatively low.

These enzymes have biological roles in the grain and become important during processes such as germination and fermentation.

In wheat and rye, endogenous cereal proteases contribute to protein hydrolysis during sourdough fermentation. Research identifies aspartic proteinases and carboxypeptidases among the important proteolytic activities in wheat and rye flours, with activity under acidic conditions.

The extent of proteolysis depends on:

• Cereal variety
• Grain condition
• Protein composition
• Enzyme activity
• pH
• Temperature
• Water availability
• Fermentation time
• Microbial population
• Analytical method

Therefore, protease activity should not be described using one universal value or operating condition.

Protease vs Peptidase

Proteases and peptidases are closely related but can be distinguished by their typical substrates and modes of action.

In cereal fermentation, these enzyme activities can operate together.

A simplified pathway is:

Cereal proteins → Proteases → Peptides → Peptidases → Amino acids and smaller peptides

The actual reaction pathway is more complex and depends on the enzymes present and the characteristics of the substrate.

Proteolytic Activity in Wheat Flour

Wheat flour contains endogenous proteolytic activity.

The activity in mature, sound grain is generally relatively low, but it can become more relevant during processing and fermentation.

The source material associated with this article reports proteolytic activity in wheat flour at an acidic pH around 4.1 and suggests that this activity may be relevant to fermentation. This value should not be interpreted as a universal optimum pH for wheat proteases.

Proteases differ in their pH profiles, substrate specificity, and stability. Research on wheat and rye sourdough identifies endogenous cereal proteases that function under acidic conditions.

For this reason, enzyme performance should be evaluated using the specific cereal system and analytical method under investigation.

How Proteases Break Down Cereal Proteins

Cereal proteins provide substrates for proteolytic enzymes.

In wheat flour, gluten proteins, particularly gliadins and glutenins, are important because they contribute to dough structure.

Proteolysis modifies these proteins by hydrolyzing peptide bonds.

A simplified pathway is:

Gluten proteins → Proteolysis → Smaller proteins → Peptides → Amino acids

The extent of hydrolysis is important.

Controlled proteolysis

Controlled protein hydrolysis can modify:

• Dough resistance
• Dough extensibility
• Protein solubility
• Peptide formation
• Fermentation-related nitrogen availability

Excessive proteolysis

Excessive protein hydrolysis can weaken the gluten network and alter dough handling and gas-retention properties.

Research on sourdough fermentation confirms that the degree of cereal-protein degradation is an important factor affecting bread quality.

The objective in baking is therefore not maximum protease activity. The objective is controlled protein modification appropriate to the process.

Proteases and Dough Quality

Wheat dough depends heavily on the structure and interactions of gluten proteins.

During dough development and fermentation, proteolytic reactions can modify the gluten network.

This can affect:

• Dough strength
• Dough extensibility
• Dough handling
• Gas retention
• Bread volume
• Crumb structure

A controlled degree of proteolysis may be useful in some formulations, while excessive hydrolysis can compromise dough structure.

The effect depends on the type and amount of proteolytic activity, flour characteristics, fermentation conditions, and desired product properties.

Proteases and Fermentation

One important consequence of cereal proteolysis is the formation of soluble nitrogen-containing compounds.

A simplified sequence is:

Cereal proteins → Proteases → Peptides → Peptidases → Smaller peptides and amino acids

These compounds contribute to the pool of soluble nitrogen available during fermentation.

The original source specifically identifies peptidases as potentially important in producing soluble organic nitrogen used by yeast during fermentation.

This should be interpreted carefully.

Proteolysis can influence nitrogen availability, but the amount and form of nitrogen available to microorganisms depend on:

• Protein substrate
• Protease activity
• Peptidase activity
• Microbial species
• Fermentation conditions
• Peptide and amino-acid composition

Therefore, it is more accurate to say that proteolysis can contribute to microbial nitrogen availability rather than claiming that increased protease activity automatically increases fermentation.

Proteases in Sourdough Fermentation

Proteolysis is an important biochemical process in wheat and rye sourdough.

During fermentation, acidification can influence cereal proteases and the accessibility of protein substrates.

Research indicates that acidification and changes in gluten structure can increase cereal protease activity and substrate accessibility. Microbial peptidases can then contribute to the accumulation of amino acids and other nitrogen-containing metabolites.

A simplified model is:

Wheat proteins → Cereal proteases → Peptides → Microbial peptidases → Amino acids

These reactions can influence bread flavour, texture, and other quality characteristics.

However, sourdough proteolysis must remain controlled in conventional bread production because excessive gluten degradation can adversely affect dough structure.

Proteases in Baking

Proteases can be used in bakery processing to modify wheat proteins.

Potential technological effects include:

• Modification of gluten structure
• Changes in dough rheology
• Changes in dough extensibility
• Protein hydrolysis
• Peptide formation
• Modification of dough handling properties

The appropriate degree of proteolysis depends on the product and process.

For example, a process requiring highly extensible dough may have different protease requirements from one requiring strong gas retention.

Protease dosage should therefore be established through process validation rather than through a generic recommended value.

Proteases in Brewing and Malting

Proteolysis also occurs during cereal malting and brewing.

During germination and malting, cereal proteins are hydrolyzed into smaller nitrogen-containing compounds.

These changes can influence the soluble nitrogen content of the cereal-derived extract and the availability of nitrogenous compounds during subsequent fermentation.

The extent of proteolysis depends on:

• Cereal variety
• Grain condition
• Germination
• Malting conditions
• Enzyme activity
• Processing conditions

Proteolysis therefore forms part of the broader biochemical transformation of cereal grain during malting.

Proteases in Food Protein Hydrolysis

Proteases are also used intentionally to hydrolyze food proteins.

Applications include the production of:

• Protein hydrolysates
• Peptide-rich ingredients
• Hydrolyzed proteins
• Modified protein ingredients

Different proteases produce different peptide profiles because enzyme specificity varies.

The choice of enzyme therefore depends on the desired degree of hydrolysis and final product characteristics.

FDA’s current information on enzyme preparations used in food includes protease-containing preparations and describes specific regulatory pathways for enzyme preparations.

Proteases in Meat Processing

Proteolytic enzymes are also used in meat-processing applications.

Certain food-enzyme preparations can hydrolyze structural proteins and modify meat texture.

However, enzyme selection and use conditions must be specific to the intended application.

Health Canada’s current permitted food-enzyme list includes protease preparations for specified uses including meat tenderizing preparations, prepared meat and poultry, and other food applications under the conditions listed by Health Canada.

This demonstrates why food-enzyme regulatory status should always be evaluated according to the specific enzyme source, food application, and jurisdiction.

Measuring Proteolytic Activity

Several analytical approaches can be used to measure proteolytic activity.

One general approach measures the formation of soluble protein or peptide material following enzyme hydrolysis.

A simplified analytical concept is:

Protein substrate + Protease → Soluble hydrolysis products

The resulting soluble fraction can then be measured using an appropriate analytical procedure.

However, protease activity is not represented by one universal assay.

Results can vary according to:

• Protein substrate
• Enzyme concentration
• pH
• Temperature
• Reaction time
• Extraction procedure
• Detection method

Therefore, a reported protease activity value should always be accompanied by the analytical method and test conditions.

Factors Affecting Protease Activity

pH

Proteases differ substantially in their pH activity profiles.

Some cereal proteases operate under acidic conditions, while other protease preparations may have different activity ranges.

The reported pH of approximately 4.1 for proteolytic activity in wheat flour should therefore be treated as a source-specific observation, not a universal optimum.

Temperature

Temperature affects both protease reaction rate and enzyme stability.

As temperature changes, the balance between catalytic activity and enzyme stability also changes.

Protein substrate

Protease performance depends strongly on the structure and accessibility of the protein substrate.

Wheat gluten proteins, milk proteins, meat proteins, and other food proteins have different susceptibility to enzymatic hydrolysis.

Reaction time

Increasing reaction time can increase protein hydrolysis, but excessive hydrolysis may produce undesirable changes in the final product.

Proteases During Cereal Germination

Proteolytic enzymes have important biological functions during cereal germination.

Cereal storage proteins provide nitrogen-containing reserves for the developing plant.

During germination, proteolytic systems participate in the mobilization of these storage proteins.

This biological function differs from the intentional addition of commercial proteases during food processing.

The distinction is important when interpreting cereal enzyme activity measurements because endogenous enzyme activity and added commercial enzyme activity are not equivalent.

Food Safety and Regulatory Considerations

Food enzyme preparations require appropriate regulatory evaluation and quality control.

Important considerations include:

• Enzyme identity
• Production organism
• Production strain
• Manufacturing process
• Purity
• Intended food application
• Conditions of use
• Applicable jurisdiction

Canada

Health Canada’s current List of Permitted Food Enzymes, published April 14, 2026, lists protease preparations from specified sources for defined food applications. Listed applications include beer, bread, white flour, whole wheat flour, prepared meat and poultry, hydrolyzed proteins, meat-tenderizing preparations, plant-based beverages, and other specified foods. The list specifies conditions of use, including good manufacturing practice where applicable.

Therefore, Canadian authorization should be checked against the exact enzyme preparation, source, food, and conditions of use.

United States

FDA maintains a partial list of enzyme preparations used in food and explains that enzyme preparations can be subject to different regulatory pathways, including food-additive regulations and GRAS determinations.

FDA’s listed GRAS substances include specific protease preparations and protease-containing enzyme products for defined uses.

Regulatory status should therefore be verified for the specific preparation and intended use, rather than assuming that all proteases have the same regulatory status.

Protease Quality Control in Food Manufacturing

Food manufacturers using protease preparations should establish appropriate controls for both the enzyme and the process.

Important controls can include:

• Supplier qualification
• Enzyme identity
• Activity specification
• Certificate of analysis
• Lot traceability
• Storage conditions
• Microbiological specifications
• Production-organism information
• Regulatory documentation
• Process-performance verification

The enzyme supplier’s specification should be matched to the actual food-processing application.

Common Mistakes About Proteases

Mistake 1: “All proteases have the same optimum pH.”

Correction: Protease activity depends on enzyme type, source, substrate, formulation, and process conditions.

Mistake 2: “pH 4.1 is the optimum pH for wheat proteases.”

Correction: The supplied source reports proteolytic activity associated with approximately pH 4.1. This should not be presented as a universal optimum for wheat proteases.

Mistake 3: “More protease always improves bread.”

Correction: Controlled proteolysis can modify dough properties, but excessive protein hydrolysis can weaken gluten structure.

Mistake 4: “Protease activity automatically increases yeast fermentation.”

Correction: Proteolysis can contribute to soluble nitrogen availability, but fermentation response depends on the microorganism, nutrient composition, substrate, and process conditions.

Mistake 5: “Proteases and peptidases are exactly the same.”

Correction: They are related proteolytic enzymes, but their typical substrates and sites of action differ.

Mistake 6: “One protease activity value can be compared across all laboratories.”

Correction: Protease assays are method-dependent. Substrate, pH, temperature, reaction time, extraction, and detection procedures can affect the result.

Frequently Asked Questions About Proteases

What are proteases in food processing?

Proteases are enzymes that hydrolyze proteins into smaller peptides and, through further proteolytic activity, amino acids. They are used in applications including baking, fermentation, protein hydrolysis, brewing, and meat processing.

What is the role of proteases in wheat flour?

Wheat flour naturally contains proteolytic enzymes. Their activity is relatively low in mature, sound grain but can contribute to protein hydrolysis during processing and fermentation.

What is the difference between protease and peptidase?

Proteases generally hydrolyze proteins or larger peptide substrates, while peptidases hydrolyze peptide bonds in smaller peptide substrates and can contribute to amino-acid formation.

How do proteases affect bread dough?

Proteases modify cereal proteins, including gluten proteins. Controlled proteolysis can change dough rheology and extensibility, while excessive hydrolysis can weaken the protein network.

Why are proteases important during fermentation?

Proteolysis can convert cereal proteins into soluble peptides and amino acids, contributing to the pool of nitrogen-containing compounds available to microorganisms.

Does protease increase yeast fermentation?

Proteolysis can influence nitrogen availability and may affect microbial growth and fermentation performance, but the effect depends on the complete fermentation system.

What happens if too much protease is used in dough?

Excessive proteolysis can weaken gluten structure and reduce dough strength and gas-retention capacity.

Does wheat flour naturally contain proteases?

Yes. Mature cereal grains contain endogenous proteases and peptidases, although their activity is generally relatively low in mature, sound grain.

Is protease regulated for use in food?

Yes. Food-enzyme requirements depend on the specific enzyme preparation, source, intended application, conditions of use, and jurisdiction. Canada and the United States have specific regulatory frameworks governing food-enzyme use.

Practical Guidance for Food Manufacturers

When evaluating proteases for a food-processing application:

1. Define the desired protein-modification objective.
2. Identify the target protein substrate.
3. Select an enzyme with an appropriate activity profile.
4. Evaluate the enzyme under actual processing conditions.
5. Use a validated analytical method to monitor proteolysis.
6. Control enzyme dosage to prevent excessive protein degradation.
7. Assess the effect on the relevant product-quality attributes.
8. Verify supplier specifications and lot traceability.
9. Confirm regulatory status in every target market.
10. Reassess the process when the enzyme preparation or major processing conditions change.

Conclusion

Proteases are important protein-hydrolyzing enzymes in cereals and food processing.

Mature, sound cereals naturally contain proteases and peptidases, generally at relatively low activity. During germination, fermentation, and processing, proteolytic activity can contribute to the conversion of cereal proteins into peptides and smaller nitrogen-containing compounds.

In wheat-based fermentation, these reactions can influence gluten structure, dough properties, nitrogen availability, fermentation, flavour, and bread quality. Research on sourdough confirms that cereal proteases and microbial peptidases contribute to protein and peptide metabolism during fermentation.

For food manufacturers, the objective is not simply to maximize protease activity. Successful processing requires controlled proteolysis matched to the substrate, enzyme preparation, processing conditions, desired product characteristics, and applicable regulatory requirements.

References

1. Gänzle, M. G., Loponen, J., & Gobbetti, M. (2008). Proteolysis in sourdough fermentations: Mechanisms and potential for improved bread quality. Trends in Food Science & Technology, 19(10), 513–521.
2. Health Canada. (2026). List of Permitted Food Enzymes. Government of Canada. Published April 14, 2026.
3. U.S. Food and Drug Administration. Enzyme Preparations Used in Food (Partial List). FDA.
4. U.S. Food and Drug Administration. Bacterially-derived protease enzyme preparation. 21 CFR §184.1150 / GRAS documentation.
5. Food Chemicals Codex. Enzyme Preparations. Current applicable edition should be verified before publication or commercial specification.
6. Supplied cereal-enzyme source material. Used for the source-specific discussion of endogenous cereal proteases, peptidases, soluble nitrogen, and the reported acidic proteolytic activity.