Inside a flour blend: strength, tenacity and extensibility

A baker rarely chooses flour under ideal conditions.

The available flour may be strong enough for a long fermentation but too tenacious for easy shaping. Another flour may stretch readily but lack the strength required by the intended process. A new harvest can also behave differently from the previous lot, even when the product name remains unchanged.

Blending offers a practical response. Instead of asking one flour to provide every property, the baker combines several flours so their technical profiles move toward a more useful balance.

Can this adjustment be reasoned from supplier specifications rather than performed only by trial and error?

Why blend flours?

Bakers blend flours for several reasons:

• adapt available flour to a specific use;
• balance resistance and extensibility;
• increase or reduce overall strength;
• reduce variation between flour lots;
• combine a functional flour with a locally available or less expensive flour;
• create more consistent starting point before production trials.

For example, adding a stronger flour may help support a longer fermentation. Adding a more extensible flour may move the calculated balance away from excessive tenacity. Neither change guarantees a result in the dough, because hydration, mixing, fermentation and flour chemistry still matter.

A blend is therefore a formulation decision. Its purpose is not to manufacture a perfect number, but to make a deliberate compromise between available raw materials.

Supplier specifications often provide useful values:

• baking strength, $W$;
• tenacity, $P$;
• extensibility, $L$;
• configuration ratio, $P/L$;
• protein content.

These values do not describe the finished bread. They describe aspects of the dough response under standardized test conditions. Still, they provide a common technical language for comparing flours and constructing a first blend.

Question is therefore not:

What bread will this blend produce?

A more precise question is:

What technical profile results when several flour specifications are combined by mass?

What alveograph measures

The alveograph test forms a dough under defined conditions, then inflates a piece of that dough into a bubble until it ruptures. The recorded pressure curve describes resistance and deformation.

ISO 27971:2023 specifies the method for determining the alveograph properties of dough made from common wheat flour at constant hydration.

Four values are central to the blend calculation. Each answers a different practical question.

Tenacity, P

$P$ is the maximum overpressure reached during inflation. It describes the resistance of the dough to deformation.

A higher $P$ means the dough requires more pressure to expand. This is often described as greater tenacity. In formulation terms, $P$ helps identify whether the blend is moving toward a more resistant profile.

Extensibility, L

$L$ is the curve length at rupture. It describes how far the dough bubble expands before breaking.

A higher $L$ indicates greater extensibility under the test conditions. When comparing candidate blends, $L$ helps show which one can deform further before rupture in the standardized test.

Configuration ratio, P/L

The ratio connects both dimensions:

$$\frac{P}{L}$$

A high value describes a profile dominated by resistance relative to extensibility. A low value describes a profile with more extensibility relative to resistance. The ratio is useful when two blends have similar strength but a different balance.

The ratio does not measure overall strength. Two flours can share the same $P/L$ while having very different $P$, $L$ and $W$ values.

Deformation energy, W

$W$ corresponds to the energy represented by the area under the alveograph curve. It is widely used as an indicator of flour strength. It helps compare how the blend moves between weaker and stronger starting flours.

Because $W$ depends on the complete curve, it should not be interpreted independently from $P$ and $L$. Research examining relationships among alveograph parameters shows that $W$ reflects both curve magnitude and shape, while $P/L$ provides separate information about the balance between tenacity and extensibility.

Representing a blend

Suppose a blend contains $n$ flours. Each flour has a mass $m_i$ and a technical value $q_i$.

Total flour mass is:

$$M=\sum_{i=1}^{n}m_i$$

Mass fraction of each flour is:

$$x_i=\frac{m_i}{M}$$

with:

$$\sum_{i=1}^{n}x_i=1$$

For a first technical approximation, each primary descriptor can be combined using a weighted mean. Mass fraction matters because 10% of a strong flour cannot contribute as much as 60% of the same flour.

Calculating W, P and L

Blend strength is the weighted contribution of every flour:

$$W_{\text{blend}}=\sum_{i=1}^{n}x_iW_i$$

Same calculation applies to tenacity:

$$P_{\text{blend}}=\sum_{i=1}^{n}x_iP_i$$

Then to extensibility:

$$L_{\text{blend}}=\sum_{i=1}^{n}x_iL_i$$

Protein content follows same mass balance:

$$Protein_{\text{blend}}=\sum_{i=1}^{n}x_iProtein_i$$

Each equation asks the same concrete question: how much does each flour contribute at its actual proportion? These calculations establish a linear technical profile. They do not reproduce a laboratory alveograph curve.

Why P/L must be recalculated

Ratios should not be averaged directly.

Correct sequence is:

1. calculate blended $P$;
2. calculate blended $L$;
3. divide resulting values.

$$\left(\frac{P}{L}\right)_{\text{blend}} = \frac{P_{\text{blend}}}{L_{\text{blend}}}$$

Consider equal blend of two flours:

Flour	P	L	P/L
A	120	80	1.50
B	60	120	0.50

Direct average of ratios gives:

$$\frac{1.50+0.50}{2}=1.00$$

But blended primary values are:

$$P_{\text{blend}}=90$$ $$L_{\text{blend}}=100$$

Therefore:

$$\left(\frac{P}{L}\right)_{\text{blend}}=\frac{90}{100}=0.90$$

The difference appears because a ratio is a nonlinear transformation. Averaging the displayed $P/L$ values would make the blend look perfectly balanced at 1.00, while the values actually combined by mass give 0.90. That difference can change the comparison between two candidate blends.

Worked blend

Suppose a baker wants to soften the profile of strong flour A without replacing it completely. Flour B is weaker and more extensible. The first trial uses:

• 60% flour A with $W=300$, $P=100$, $L=100$, protein 13%;
• 40% flour B with $W=200$, $P=60$, $L=120$, protein 11%.

Step 1: calculate strength

Each flour contributes its own $W$ multiplied by its share of the blend:

$$W_{\text{blend}}=\underbrace{0.60(300)}_{180}+\underbrace{0.40(200)}_{80}=260$$

The calculated $W$ sits between 300 and 200, closer to flour A because flour A represents 60% of the blend.

Step 2: calculate tenacity

$$P_{\text{blend}}=0.60(100)+0.40(60)=84$$

Compared with flour A alone, the calculated $P$ falls from 100 to 84. The blend moves toward a less tenacious profile.

Step 3: calculate extensibility

$$L_{\text{blend}}=0.60(100)+0.40(120)=108$$

The calculated $L$ rises from 100 to 108 because flour B contributes greater extensibility.

Step 4: recalculate balance

$$\left(\frac{P}{L}\right)_{\text{blend}}=\frac{84}{108}=0.78$$

$P/L$ falls below the value of flour A. This confirms that the calculated profile moved toward extensibility, not only toward lower strength.

Step 5: calculate protein

$$Protein_{\text{blend}}=0.60(13)+0.40(11)=12.2\%$$

Protein follows the expected mass balance, but it does not explain $W$ by itself. Two flours with the same protein content can have different gluten quality and different alveograph profiles.

The result is a compact technical description:

Descriptor	Calculated blend
W	260
P	84
L	108
P/L	0.78
Protein	12.2%

Flour blend studio

Enter supplier values. Result uses mass-weighted linear blending.

Reset

Flour A

Blend%WP mmL mmProtein%

Flour B

Blend%WP mmL mmProtein%

Flour C

Blend%WP mmL mmProtein%

Blend totals 100%.

Calculated technical profile

W

260

P

84.0 mm

L

108.0 mm

P/L

0.78

Protein

12.2%

Flour A 60%Flour B 40%

The studio lets the reader reproduce the calculation, replace the technical values with supplier data and move the proportions gradually. It normalizes the entered proportions when their total differs from 100%, but reports the mismatch explicitly. This helps explore relative contributions without hiding a formulation error.

A useful first experiment is to keep both flour profiles unchanged and move flour A from 60% to 70%. Observe which descriptors move most and which remain comparatively stable.

Reading the result as a baker

The result does not say whether the dough will mix well, ferment correctly or produce the desired loaf. It creates a comparison between formulation options.

Ask practical questions:

• What changes if flour A moves from 60% to 70%?
• Does $W$ increase while $P/L$ stays inside useful region?
• Is stronger profile obtained by increasing tenacity more than desired?
• Can another pair of flours reach similar $W$ with different balance between $P$ and $L$?

For example, increasing flour A in the worked blend raises the calculated $W$, $P$ and protein while lowering the contribution of the more extensible flour B. The studio makes this direction visible before the baker weighs a trial batch.

This is the main value of the calculation: not declaring a blend correct, but making the effect of each proportion explicit.

What this profile can communicate

A calculated blend provides a concise way to compare formulations.

It can show:

• whether strength descriptor moves toward target region;
• whether tenacity increases faster than extensibility;
• how strongly one flour dominates final profile;
• how protein content changes with blend ratio;
• whether two different blends produce similar calculated descriptors.

This is useful during formulation because each change remains traceable. If 10% of one flour is replaced, its contribution to each descriptor can be calculated directly.

What this profile cannot establish

A weighted average is an assumption, not measured rheology. Calculated profile remains a working hypothesis until the actual blend is mixed, processed and, when needed, tested with a standardized method.

The real blend may depart from the linear calculation because its response depends on:

• gluten quantity and quality;
• gliadin and glutenin balance;
• damaged starch;
• particle-size distribution;
• enzyme activity;
• water absorption;
• ash and fibre content;
• additives and processing aids;
• conditioning and alveograph protocol.

Protein content alone cannot determine $W$. Two flours with an equal protein percentage can have different gluten quality and different alveograph curves.

Likewise, the calculated $W$, $P$ and $L$ should not be presented as certified values. Only measurement of the actual blend under standardized conditions provides a laboratory profile.

Studies of wheat flours confirm that alveograph parameters describe connected but distinct aspects of a dough. $W$ relates to the curve area, while $P/L$ represents its shape. Both also depend on hydration and the complete flour matrix.

A useful workflow

A linear blend calculation fits the early formulation stage:

1. collect supplier specifications produced with comparable methods;
2. enter $W$, $P$, $L$ and protein for each flour;
3. choose mass proportions;
4. calculate blended technical profile;
5. compare candidate blends;
6. prepare laboratory or production trial;
7. measure real blend and record deviation from calculation.

Repeated measurements can later reveal whether particular flour families combine approximately linearly or require a correction model.

Conclusion

Flour blending can be described with a transparent mass balance.

$W$, $P$, $L$ and protein can be combined as weighted descriptors. $P/L$ must then be recalculated from blended $P$ and $L$, not averaged independently.

The result is a technical profile for comparison and formulation. It is not a claim about the final bread and not a substitute for an alveograph measurement.

That distinction makes the calculation useful. It provides a structured starting point while keeping the boundary between formulation estimate and experimental evidence visible.

References

• International Organization for Standardization, ISO 27971:2023, determination of alveograph properties of dough at constant hydration.
• T. Jødal and K. L. Larsen, Investigation of relationships between alveograph parameters, Scientific Reports 11, 2021.
• G. G. Codină et al., Wheat flour dough alveograph characteristics predicted by Mixolab regression models, Journal of the Science of Food and Agriculture 92, 2012.