Digestion

Enzyme Stability and Storage: Why Temperature, Moisture and Time Matter

Enzymes are proteins, and their activity can change during processing and storage. Temperature, moisture, pH and time all influence how well enzyme activity is retained, which is why the way an enzyme-containing ingredient is produced, packaged and stored matters as much as simply knowing which enzymes are present.

Science explainer

Enzyme Stability and Storage: Why Temperature, Moisture and Time Matter

Content type

Science explainer

Focus

Enzyme activity, temperature stability, moisture, pH and storage conditions

The big question

It is easy to talk about whether a food or ingredient contains enzymes.

But presence alone is not the whole story.

For an enzyme to contribute meaningful biological activity, it must still be active when it is used.

Enzymes are proteins with complex three-dimensional structures. Their activity depends on those structures remaining sufficiently intact.

Processing, heat, moisture, acidity and storage can all influence this.

The big question is:

What determines whether an enzyme remains active from manufacture through storage and eventually into the digestive tract?

How do scientists study it?

Scientists assess enzyme stability by measuring activity under controlled conditions.

Rather than simply asking whether an enzyme molecule is present, they measure how effectively it can still catalyse a particular reaction.

Several factors are especially important.

Temperature

Increasing temperature generally increases the speed of chemical reactions up to a point.

Beyond an enzyme's useful temperature range, its structure can begin to change.

This process is known as denaturation.

Once sufficiently denatured, the enzyme may lose much or all of its catalytic activity.

Moisture

Water is essential for many enzymatic reactions.

But during storage, excessive moisture can also increase chemical and biological instability.

Controlling water availability can therefore be important when preserving enzyme-containing ingredients.

Enzymes have characteristic pH ranges within which they function most effectively.

Large changes in acidity or alkalinity can alter the electrical interactions that help maintain enzyme structure and influence the shape of the active site.

Time

Enzyme activity can decline gradually during storage.

The rate of that decline depends on the enzyme itself and the surrounding environment.

Processing

Drying, heating, concentration, mixing and other manufacturing steps can all affect retained enzyme activity.

This is why enzyme preservation has to be considered throughout manufacture rather than only after a product has been packaged.

What can we measure?

Several concepts are useful when thinking about enzyme stability.

Enzyme activity

Activity describes what an enzyme can actually do.

For example, amylase activity can be assessed by measuring its ability to break particular bonds within starch.

Two materials could contain similar amounts of enzyme protein but have very different levels of active enzyme.

Denaturation

Denaturation occurs when an enzyme's three-dimensional structure is altered sufficiently to interfere with its function.

Heat is one common cause, although extreme pH and other environmental conditions can also contribute.

Residual activity

Researchers may compare enzyme activity before and after processing or storage.

The proportion that remains is sometimes described as residual activity.

Shelf stability

Repeated measurements over time can show whether activity remains relatively stable or declines under particular storage conditions.

Thermal stability

Scientists can expose an enzyme to different temperatures and measure how much activity remains.

Different enzymes can have very different thermal tolerances.

There is therefore no single temperature at which every digestive enzyme suddenly stops working.

What have we learned?

The central lesson is that enzyme activity is not guaranteed simply because an enzyme was present at the beginning of manufacture.

Several practical principles follow.

Heat can reduce enzyme activity

Many enzymes are sensitive to prolonged or excessive heating.

This is especially relevant when comparing manufacturing processes involving substantial heat with processes designed to preserve biological activity.

Different enzymes behave differently

Amylases, proteases, lipases and carbohydrate-active enzymes do not necessarily have identical stability profiles.

A process that preserves one enzyme well may affect another differently.

The surrounding matrix matters

An enzyme does not exist in isolation.

Sugars, proteins, water content, minerals and other components of a food or extract can influence its stability.

Storage conditions matter

Temperature, exposure to moisture and time can influence how much activity remains.

This is why storage recommendations are part of maintaining product quality rather than simply a packaging convenience.

Activity should ideally be measured

The strongest evidence that an enzyme-containing ingredient remains active is a direct assay of enzyme activity rather than an assumption based on the original raw material.

Why does this matter?

Enzyme science involves two distinct questions.

The first is:

Which enzymes are present?

The second is:

How much useful activity remains?

The second question is often the more important one.

This is particularly relevant to malt-derived enzyme systems.

Germination can produce a broad range of enzyme activities, but subsequent processing must be designed so that those activities are not unnecessarily lost.

That creates a simple sequence:

Enzyme generation → Processing → Storage → Retained activity

Each stage can influence the next.

It also explains why two ingredients described using similar words may not necessarily have equivalent biochemical activity.

The source of the enzymes, the way the ingredient was processed and the conditions under which it was stored all matter.

To see how malting creates an active enzyme system, read how Enzyme Rich Malt Extract is made.

Our ingredient guide explains what Enzyme Rich Malt Extract is and how it differs from an isolated enzyme blend.

What should we keep in mind?

Several cautions are important when interpreting enzyme stability data.

Laboratory conditions are simplified

An enzyme may behave differently in a purified laboratory assay compared with a complex food or biological matrix.

Different assays give different information

Enzyme activity depends on the substrate, pH, temperature and analytical method used.

Results from different laboratories are not always directly comparable.

Stability is enzyme-specific

There is no universal storage rule that applies equally to every enzyme.

Storage stability and digestive activity are different questions

An enzyme can remain active during storage but still encounter very different conditions once consumed.

The stomach and small intestine expose enzymes to changing pH, endogenous digestive enzymes and varying transit times.

Presence does not demonstrate benefit

Retaining enzyme activity establishes biochemical potential.

It does not, by itself, show that consuming that enzyme will produce a measurable biological or health effect in a dog.

That requires separate experimental evidence.

Sources and further reading

References

Further reading:

Whitaker JR. Principles of Enzymology for the Food Sciences. Marcel Dekker.

Fennema OR, Damodaran S, Parkin KL. Fennema's Food Chemistry. CRC Press.

Briggs DE. Malts and Malting. Blackie Academic & Professional.

Bamforth CW. Scientific principles of malting and brewing. American Society of Brewing Chemists.

General enzyme and food-science literature demonstrates that temperature, pH, moisture, processing conditions and time can influence protein structure and retained enzyme activity.

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