Falling Number In Flour: Why It Matters For Sourdough?

If you've ever come across Hagberg Falling Number on a flour specification sheet and wondered what it means for your sourdough baking, you're not alone. This number - measured in seconds - reveals how active the natural enzymes are inside your flour and plays a surprisingly large role in how your dough ferments, rises, and bakes. Understanding falling number in flour helps sourdough bakers make more consistent, better-quality bread, especially when working with different flours, harvests, or grain varieties.

Jump to:

• What Is the Falling Number (Hagberg Test)?
• The Science Behind It: Alpha-Amylase and Enzymatic Activity
• Typical Falling Number Ranges and What They Mean
• Why Falling Number Matters in Sourdough Baking
• How to Adjust for Low or High Falling Numbers
• How to Find the Falling Number of Your Flour
• Does Hagberg Falling Number Only Apply to Wheat Flour?
• Examples of Falling Number Values in Common Flours
• Why It's Useful for Home Sourdough Bakers
• Final Thoughts

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What Is the Falling Number (Hagberg Test)?

The falling number test (or FN test) is an industry standard used by flour mills and the grain trade to measure the level of enzyme activity in wheat flour. Developed by Hagberg and Perten in the 1960s, the test is simple in concept but scientifically powerful.

A small flour sample is mixed with water to make a paste and heated in a glass tube. A falling paddle (or plunger) is then dropped into the mixture. The number of seconds it takes to reach the bottom of the test tube is recorded - this is the Falling Number value.

• A low Falling Number means the paste is thin, showing high alpha-amylase activity (enzymes breaking down starch rapidly).
• A high Falling Number means the paste is thick, showing low enzyme activity (less starch breakdown).

In short, the Falling Number is an inverse relationship to enzyme activity - the higher the number, the less active the enzymes.

The Science Behind It: Alpha-Amylase and Enzymatic Activity

The key enzyme measured by the FN test is alpha-amylase, a form of amylolytic enzyme that breaks down starch granules in wheat flour into smaller sugars like maltose. These sugars are a food source for yeast and bacteria during the fermentation process, helping the dough rise and develop flavour.

However, the amount of alpha-amylase must be just right.

• Too much activity (low Falling Number): The dough can become sticky, weak, and overly slack during fermentation. Baked loaves may have low volume, gummy crumb, and poor keeping quality.
• Too little activity (high Falling Number): The dough may ferment sluggishly, producing pale crusts and dense crumbs because there isn't enough sugar for proper browning or yeast activity.

In the wheat field, alpha-amylase activity is largely determined by pre-harvest sprouting (grains starting to germinate before harvest) or late maturity alpha-amylase formation. These issues can be caused by wet weather, uneven crop ripening, or variable soil nitrogen supply. Such environmental factors lead to different FN values even among the same wheat varieties.

Typical Falling Number Ranges and What They Mean

Falling Number (seconds)	Enzyme Activity	Description	Likely Baking Results
< 200 s	Very high	Sprout damage or overactive enzymes	Sticky dough, poor volume
250–300 s	Moderate	Balanced alpha-amylase levels	Ideal for sourdough and long fermentations
300–400 s	Low	Limited enzyme activity	Tight crumb, pale crust, slower bulk fermentation

For good quality wheat flour, a Falling Number between 250 and 350 seconds is usually ideal for sourdough baking. It indicates balanced enzyme activity - enough to support fermentation without making the dough unstable.

Why Falling Number Matters in Sourdough Baking

In commercial bakeries, flour quality is carefully controlled to ensure consistent dough rise and crumb texture. But for home sourdough bakers, the FN value can explain why the same recipe behaves differently from bag to bag.

During a long fermentation, the activity of alpha-amylase has a vital role:

• It releases sugars slowly, feeding the natural yeasts and lactic acid bacteria.
• It helps achieve better crust colour through the Maillard reaction.
• It influences the elasticity and strength of the dough through balanced starch breakdown.

Flours with low Falling Numbers (high enzyme activity) often lead to sticky doughs, collapsing loaves, and irregular air pockets. In contrast, high Falling Number flours may need slightly longer fermentation times or the addition of malted flour to encourage a more active rise.

In essence, the Hagberg Falling Number offers a window into how your flour will behave during long sourdough fermentation - something protein content of flour alone can't tell you.

How to Adjust for Low or High Falling Numbers

If you know your flour's FN value, you can adapt your method for best results:

Falling Number is too low (too much enzyme activity):

• Use shorter bulk fermentation and proofing times.
• Keep dough slightly cooler during fermentation.
• Blend with a stronger flour or one with a high Hagberg value.
• Avoid adding malted flour - it will worsen the problem.

Falling Number is too high (too little enzyme activity):

• Add a tiny amount (0.1-0.2%) of diastatic malt flour to the mix to increase alpha-amylase enzyme activity.
• Use warmer bulk fermentation temperatures.
• Allow for a slightly longer rise time or increase the proportion of active starter.

Small changes like these can help compensate for different FN values in your flour, especially if you bake with freshly milled or stone-ground grain flours.

How to Find the Falling Number of Your Flour

Not every bag of flour will list this information. However, most flour mills perform a falling number test as part of their quality control. You can:

• Check the mill's technical data sheet or lot number details.
• Contact the mill directly for information - many artisan or organic mills will share FN data on request.
• If you buy supermarket flour, you can gauge flour quality by observing dough behaviour: excessive stickiness or weak dough strength may hint at low Falling Numbers.

Does Hagberg Falling Number Only Apply to Wheat Flour?

While the Hagberg Falling Number is most commonly used for wheat flour, especially bread wheat (Triticum aestivum), the same principle can be applied to other grain flours such as rye, barley, or oats.

However, because these grains have different starch granules and enzyme profiles, their falling number values can't be directly compared to wheat. In practice, it remains primarily a measure for assessing wheat flour quality, particularly in relation to baking performance and sprout damage.

Examples of Falling Number Values in Common Flours

Below are some examples of typical FN values and what they mean in baking terms:

Flour Type	Typical Falling Number (s)	Enzymatic Activity	Baking Implications
Strong bread flour (hard wheat)	250–330	Balanced	Ideal for sourdough boules, sourdough sandwich loaves, and rolls. Good dough strength and predictable fermentation.
Wholemeal wheat flour	230–300	Slightly higher	Includes bran and wheat germ, which raise enzyme activity and slightly speed up fermentation.
Pastry or soft white wheat flour	350–450	Low	Low enzyme activity and weaker gluten; best for short fermentation or enriched doughs.
Rye flour	100–200	Very high	Naturally high alpha amylase causes fast starch breakdown — produces sticky doughs unless balanced with other types of flour.
Spelt flour	180–250	Moderate to high	Softer gluten and more active enzymes; dough ferments quickly and spreads more easily.
Einkorn or emmer flour	200–270	Moderate	Ancient grains with variable enzyme activity; may need shorter bulk fermentation.
Barley flour	80–150	Very high	Extremely high enzyme activity — best used in small percentages for flavour or colour, not structure.

Why It's Useful for Home Sourdough Bakers

For sourdough bakers, understanding the Hagberg Falling Number is part of learning how to read your flour. It's a risk management tool that millers and commercial bakers use to predict performance, and it can help you do the same at home.

Knowing whether your flour leans towards high enzyme activity or low enzyme activity allows you to adjust hydration, fermentation time, and temperature. In other words, it helps you get the most out of every grain - even if you're working with variable flours from different harvests or organic sources.

For more help with choosing the right flour, head to our flour for sourdough beginners article.

Final Thoughts

The Falling Number test may sound technical, but it tells a simple story: how lively your flour is. A flour's Falling Number value reflects not just its enzymatic activity, but also the grain quality, weather at harvest, and milling process. For sourdough bakers, understanding it means baking with greater confidence and precision.

Once you've explored protein content, ash level, P/L ratio, and Falling Number, you'll be reading flour labels like a professional - and your sourdough will thank you for it.