What Affects Pizza Digestibility? A Science-Based Review and Discussion

Many bakers have heard the claim that long-fermented dough is “healthier” or “easier to digest.” But is there any truth to it? In this article, we’ll explore what actually affects the digestibility of pizza – backed by scientific studies – and which factors may not matter as much as commonly believed

Introduction: Dough, Pizza, and Digestibility

The world of baking, and pizza in particular, is full of myths: assumptions treated as absolute truths despite often lacking scientific support. One especially common belief is that long fermentation makes pizza dough more “digestible” or even “healthier.”

This idea has gained widespread acceptance among both home bakers and professionals, and the concept of dough “digestibility” receives prominent attention in many Italian pizza courses and literature.

Personally, I’ve always been skeptical about the link between fermentation time and how “digestible” a dough/pizza is, for a few key reasons:

1. I’ve never experienced any noticeable difference in digestibility between doughs fermented for different lengths of time.
2. The claim that long fermentation improves digestibility is especially popular in Italy, and mostly tied to Italian pizza. When it comes to breads or other baked goods, especially outside of Italy, this topic receives far less attention, and the discussions around it are much less clear-cut.
3. “Digestibility” is an abstract and context-dependent concept. While it’s easy to toss the word around, without a clear and consistent definition, the term becomes meaningless.

To assess whether this belief holds water, I decided to investigate it more deeply – and the findings are presented here.

We’ll begin by looking at what dough actually is in terms of its nutritional makeup and the processes it undergoes during fermentation. From there, we’ll explore the concept of digestibility and how it relates to dough.

Throughout the article, you’ll find references to many studies, some about digestibility in general, and others focused specifically on dough. We’ll also look closely at two unique studies that directly examine how different fermentation methods affect the digestibility of pizza.

Dough: What It’s Made Of and What Happens During Fermentation

To evaluate the claim that long-fermented dough is more digestible or “healthier,” we first need to understand what wheat [flour] dough is made of, and what processes it undergoes during fermentation.

Starch and Proteins: The Two Main Components of Flour

White wheat flour dough is primarily composed of:

• ~75% carbohydrates (mainly starch)
• 10–14% proteins (primarily gluten-forming proteins: glutenin and gliadin)
• ~14% moisture (water)
• Small amounts of fat, dietary fiber, minerals, and other trace elements

When it comes to fermentation and baking, the two most important components of white flour dough are carbohydrates (starch) and proteins.

Both starch and proteins are made of long chains of smaller building blocks. The human body can’t absorb these large chains directly, so digestion breaks them down into their basic units – simple sugars and amino acids, respectively.

• Carbohydrates are chains of simple sugars and serve as the body’s main source of energy. Their digestion involves gradually breaking them down into simple sugars (mostly glucose), starting in the mouth and continuing in the small intestine.
• Proteins are chains of amino acids. Their digestion takes place mainly in the stomach and small intestine, where enzymes break the chains into absorbable free amino groups.

Starch

Starch is the primary carbohydrate in wheat flour. It’s made up of glucose chains, found in two main structures: amylose and amylopectin. Glucose is the body’s main energy source and the simplest sugar that can be absorbed.

During digestion, and also during fermentation and baking, starch is broken down by amylase enzymes. These enzymes convert starch from a complex polysaccharide into single glucose molecules (monosaccharides) that the body can absorb.

Proteins

Like starch, proteins must be broken down into smaller, absorbable units, specifically, peptides and amino acids.

During digestion (and also during fermentation), proteins in flour are broken down by protease enzymes. These enzymes “cut” the long amino acid chains into free amino groups that can be absorbed by the body.

Overall, the digestion of proteins, especially those in flour, is considered more complex than that of carbohydrates.

What Happens to Dough During Fermentation

Now that we’ve identified the two main components of dough – starch and protein – let’s look at how each is affected during fermentation.

When dough ferments, two primary processes take place:

1. Starch Breakdown: Starch, a complex carbohydrate, is broken down by amylase enzymes (naturally present in flour) into simpler sugars like dextrins, maltose, and glucose.
   Yeast primarily consumes glucose for its metabolic activity; And since raw flour contains very little free glucose, yeast relies* on the amylase enzymes to generate fermentable sugars.
   *Yeast can also metabolize maltose, which it converts into glucose inside the cell using the enzyme maltase.
   
2. Protein Breakdown: During fermentation, the two main proteins in flour – glutenin and gliadin (which form gluten bonds) – are gradually broken down by protease enzymes into peptides and amino acids. This enzymatic breakdown is also responsible for the dough becoming more extensible and “weaker” as fermentation progresses.

In this sense, fermentation acts as a kind of “pre-digestion” for the dough. In the next sections, we’ll examine what this really means, and whether it has any practical impact on how the dough is digested by our body.

Understanding the Basics: Dough, Fermentation, and Digestibility

At first glance, the logic seems straightforward: the longer dough ferments, the more its starches and proteins break down, meaning less “digestive work” for our bodies, therefore – the dough should be “easier to digest,” right?

Not quite.

To better understand why this isn’t so simple, and to lay the groundwork for analyzing the studies that follow, we need to address five key points:

1. What exactly is “digestibility”?
2. How efficiently does the human body digest carbohydrates and proteins?
3. To what extent are starches and proteins broken down during fermentation, and what does that mean for human digestion?
4. How does baking affect the amount and structure of starch and proteins in dough?
5. How do scientific studies actually assess and define digestibility?

1. What Is “Digestibility”?

Every person has a unique digestive system, influenced by genetics, dietary habits, gut microbiota, and other physiological factors. As a result, how well one person digests a particular food may differ greatly from someone else.

But what does “better digestibility” actually mean?

• Feeling full for longer?
• A faster digestion rate?
• Less bloating?
• Stabilized blood sugar levels?
• Fewer digestive symptoms like gas, discomfort, or irregular bowel movements?

All of these fall under the umbrella of “digestibility,” but many are subjective and vary from person to person.

The concept of digestibility is also highly context-dependent. For someone about to exercise, a “better” food might be one that digests quickly and provides fast energy; For someone trying to manage weight or prolong satiety, a “better” food might digest more slowly and help maintain steady energy levels and blood sugar.

These are just two examples – countless other scenarios exist where personal needs, goals, or preferences redefine what “better digestibility” means. Cultural or psychological factors may also shape perceptions, leading people to feel that a food is “healthier” or “easier to digest,” even if the actual physiological effect is minimal (i.e., placebo effect).

In short: There is no one-size-fits-all definition of “better digestibility.” It’s subjective, individual, and depends heavily on the specific context.

2. The Human Body’s Efficiency in Digesting Carbohydrates and Proteins

In healthy individuals without sensitivities or allergies to specific food components, the body is remarkably efficient at digesting both carbohydrates and proteins.

Carbohydrates, particularly starch, are the body’s primary energy source – making up as much as 70–80% of daily caloric intake in many diets. Unsurprisingly, our digestive system is well-adapted to break them down quickly and efficiently.

The digestion of starch begins in the mouth, where it is broken down both mechanically (through chewing) and chemically (by salivary amylase). The process continues in the small intestine, where further breakdown by pancreatic amylase converts starch into glucose, the simplest and most absorbable sugar.

Protein digestion is also highly efficient, though it involves more steps. It begins in the stomach with the enzyme pepsin, and continues in the small intestine, where various proteases complete the breakdown into absorbable amino acids.

Scientific studies show that the main wheat proteins, glutenin and gliadin, which make up the majority of protein content in wheat flour, are digested at very high rates in healthy individuals. The ileal digestibility (a common measure of how thoroughly protein is absorbed before reaching the large intestine) typically reaches 85–90% or higher, comparable to that of other plant and animal proteins.

3. The Extent of Starch and Protein Breakdown During Fermentation

The breakdown of starch and protein during fermentation is limited – both in terms of quantity and its practical effect on digestibility. Importantly, the improvement is not linear: extending fermentation time doesn’t proportionally increase starch or protein breakdown or digestibility.

Starch Breakdown

Amylase enzymes mainly act on damaged starch – starch that was physically damaged during the milling process and is therefore more accessible to enzymatic activity. This structural damage allows amylase to more effectively break it down.

By contrast, undamaged starch, with its compact and closed structure, is mostly resistant to enzymatic activity during fermentation.

In standard flours, damaged starch content ranges from 4–12%, with most white flours falling between 5–8%. In theory, this sets the upper limit for starch breakdown; However, in practice, the actual amount broken down is significantly lower:

• Complete breakdown of all damaged starch is rare,and typically requires high amylase activity, such as from added enzymes like diastatic malt powder.
• Too much starch degradation negatively affects dough quality, resulting in sticky dough, excessive browning during baking, weak structure, and a gummy crumb.

In practice, only about 1–3% of the starch in yeast-leavened dough is broken down during fermentation. While this amount is negligible from a digestibility standpoint, it’s essential for fermentation, as it provides the sugars yeast and bacteria feed on.

Protein Breakdown

The extent of protein breakdown during fermentation varies by dough type, but in general, up to 20% of the proteins in flour can be broken down into free amino groups:

• In yeast-leavened doughs: typically 5-10%, often even less – even with very long fermentation times, due to conditions that limit proteolysis.
• In sourdough: usually 10–20%, thanks to lactic acid bacteria that lower the dough’s pH (increase its acidity) and contribute additional proteolytic enzymes – both of which enhance protein breakdown.

While breaking down proteins during fermentation can, in theory, aid digestibility by shortening protein chains, for most healthy individuals, the benefit is minimal, because the body is already highly effective at digesting wheat proteins.

4. The Effect of Baking on the Structure and Content of Starch and Proteins in Dough

During baking, the dough undergoes a series of physical and chemical changes that significantly impact the digestibility of both starch and proteins.

Starch undergoes a process known as starch gelatinization, in which its crystalline structure breaks down as it absorbs water and heat. This transformation makes the starch far more accessible to enzymatic breakdown by amylases.

Proteins also undergo significant structural changes during baking. They denature, coagulate, and form additional cross-links, which contribute to the setting and structural integrity of the final baked product. Depending on baking time and temperature, these changes can make the proteins in the finished product either more or less digestible than they were in the raw dough.

In summary: Although fermentation alters the composition of starch and proteins in dough, understanding its true effect on digestibility requires looking at the final baked product – not just the dough before it goes into the oven. It’s the baking stage that determines the final nutritional structure, and any conclusions about digestibility must take that into account.

5. How Scientific Studies Assess and Define “Digestibility”

In the realm of scientific research, where consistent, measurable, and objective variables are essential – “digestibility” is typically evaluated using one of two main approaches (occasionally a combination):

1. In Vitro Studies (Lab-Based Simulations):

These studies simulate the human digestive process in controlled lab conditions, often using test tubes or mechanical systems to mimic specific parts of the gastrointestinal tract.

• Advantages: Total control over experimental variables allows for consistent, reproducible, and objective measurements.
• Limitations: These setups cannot fully capture the complexity of digestion in the human body. Factors such as microbiota interactions, hormonal signals, or individual physiology are not easily replicated.

2. In Vivo Studies (Human Trials):

In vivo research is conducted within living organisms, usually human participants selected based on specific criteria.

These studies may use a combination of questionnaires to record subjective sensations (e.g., satiety, bloating, stomach discomfort), and clinical tests, such as blood glucose monitoring, breath hydrogen analysis, or stool sampling.

• Advantages: Reflect real-world biological responses, offering insight into how the human body truly reacts to food.
• Limitations: Many variables are difficult to control. Data often rely on self-reporting, which is vulnerable to bias, individual perception, and lifestyle factors.

Common Challenges Across Both Methods:

• In Vitro: Often too simplified to be fully representative.
• In Vivo: Too variable and subjective to yield entirely objective results.

Additionally, when researchers focus on dough-based foods like pizza, they face additional challenges:

• Dough preparation and baking involve countless variables: Slight variations in kneading, hydration, fermentation, or baking temperature can alter results dramatically.
• Ingredient choices: type of flour, yeast amount, proofing duration – have major impacts on outcomes.
• Fermentation Temperature: Studies on dough and digestibility typically use fermentation temperatures that mimic industrial bread-making processes – usually in the range of 30–35°C (85–95°F). Fermenting at such high temperatures significantly accelerates both fermentation and dough maturation, but it’s not representative of typical home baking practices. As a result, the findings from these studies often don’t reflect how dough behaves in a home setting.
• The amount of yeast used: Yeast quantity has a major impact on both fermentation and dough maturation. Therefore, the amount chosen by researchers directly and significantly affects the study’s results.
• Lack of baking expertise: Researchers are typically not bakers, and making pizza or bread involves many nuanced processes that may be overlooked without practical experience – potentially affecting the accuracy or relevance of the study’s results.
• Commercial orientation: Many studies focus on commercial settings, as these have a broader impact on consumers and are often funded by industry stakeholders. This includes higher fermentation temperatures, increased yeast quantities, advanced mixing technology, and other factors that don’t reflect typical home baking conditions.
• Practical Considerations: Dough and its final baked product should be evaluated as a whole, rather than in isolation. Improvements in digestibility on paper do not necessarily translate into a better (or even acceptable) baked outcome. In fact, theoretical gains can sometimes come at the expense of practical usability. For instance, a long-fermented dough might show favorable digestibility markers in a lab setting, yet become over-fermented in practice, difficult to work with, and produce poor baking results. In such cases, the dough may appear “better on paper” digestibility-wise, but that becomes irrelevant in the context of actual baking.

For gastrointestinal research, in vitro methods are generally preferred for their objectivity and reproducibility. But since they only simulate digestion, their real-world applicability is limited, especially considering the immense variability of individual digestive systems.

Moreover, and as discussed earlier, “digestibility” is a context-dependent and person-specific concept. The definition a study uses for digestibility has a profound effect on:

• How the study is designed.
• What data is collected.
• And how results are interpreted.

In Summary: Even within scientific literature, defining and measuring “digestibility” is anything but straightforward. While research offers valuable insights, the topic is highly complex, variable, and often subjective. No single study, or method, can fully capture the broad and nuanced reality of how we digest food.

Mid-Summary: Does Long Fermentation Have a Practical Effect on the Digestibility of Dough?

Based on the information we’ve covered so far, and before we examine studies specifically related to pizza dough – does long fermentation actually have a practical effect on the digestibility of dough or pizza?

Let’s briefly summarize the key points from the previous sections:

• Our body is efficient at digesting starch and wheat proteins: A healthy digestive system is fully capable of breaking down starch and proteins without “assistance” from fermentation. It does not rely on pre-digestion during fermentation to function properly.
• Only a limited amount of starch and protein breaks down during fermentation: In yeast-leavened dough, up to 1% of the starch and around 10% of the protein is broken down during fermentation.
• Significant protein breakdown occurs early on: Most protein breakdown happens within the first 4-6 hours of fermentation at room temperature. Extending fermentation beyond that point doesn’t necessarily lead to further breakdown or improved protein digestibility.
• The baked product – not the fermented dough – is what matters: Baking introduces numerous changes that affect digestibility. These changes may render the biochemical breakdowns that occurred during fermentation relatively unimportant.
• Digestibility is difficult to define and measure: The concept of “digestibility” is both context- and person-dependent, making it hard to quantify – even in scientific research.
  

Conclusion: Based solely on the information above, it seems clear that extending fermentation time, especially beyond a certain point, does not necessarily improve the digestibility of dough in any practical way. Even if longer fermentation shows more extensive starch and protein breakdown “on paper,” this doesn’t automatically translate to a meaningful difference in real-world digestion.

Now that we’ve laid the groundwork, we can move on to the scientific studies themselves.

Studies on the Digestibility of Pizza Dough: A Review and Discussion

Overview and Context of the Studies

The two studies presented below, both in vitro studies, offer supporting evidence for the core claim discussed earlier: that extending fermentation time beyond a certain (and relatively early) point has limited practical impact on the digestibility of pizza dough.

I chose to discuss these specific studies for several reasons:

• They focus directly on pizza dough.
• Each study defines and measures “digestibility” differently, providing a broader and more nuanced view of the topic.
• Both cover a relatively wide range of fermentation times.

Together, these aspects make the studies particularly relevant to the question at hand: whether, and to what extent, fermentation time affects the digestibility of pizza.

Below is a brief overview of the two studies (links provided in the section of each study):

1. Study of Physico-Chemical Properties of Dough and Wood Oven-Baked Pizza Base: The Effect of Leavening Time
   This study investigated how varying leavening times affected the properties of a traditional Neapolitan pizza. Digestibility was assessed quantitatively, based on the amount of starch broken down.
2. Sourdough “Biga” Fermentation Improves the Digestibility of Pizza Pinsa Romana: An Investigation through a Simulated Static In Vitro Model
   This research focused on Pizza Pinsa Romana, examining how different fermentation times influenced several nutritional and digestive markers in the final baked product. It used both quantitative and qualitative methods to assess digestibility.

Each study will be analyzed with the following structure:

• A summary of the study’s methodology
• Key results and findings
• Conclusions, with commentary on their relevance to dough fermentation and digestibility

But before diving into the studies themselves, we first need to examine one final foundational topic: the types of starch found in dough and how each affects digestion.

Essential Introduction: Types of Starches and Their Effects on Digestion

From a nutritional standpoint, starches are not all created equal. They are categorized into three main types, each with different effects on digestion, blood sugar, and overall health:

1. Rapidly Digestible Starch (RDS)
2. Slowly Digestible Starch (SDS)
3. Resistant Starch (RS)

1. Rapidly Digestible Starch (RDS):
This type of starch is broken down very quickly, usually within 20 minutes, by enzymes in the small intestine. It’s rapidly converted into glucose, leading to a sharp and immediate spike in blood sugar levels, followed by a noticeable drop (commonly known as a “sugar crash”).

High intake of RDS is associated with unstable blood sugar, increased hunger, and may contribute to long-term risks like metabolic syndrome and type 2 diabetes.

2. Slowly Digestible Starch (SDS):
SDS takes longer to digest, between 20 and 120 minutes – also in the small intenstine. This slower breakdown results in a more gradual release of glucose into the bloodstream, leading to steadier energy levels and longer-lasting satiety.

SDS is considered more beneficial than RDS, particularly in diets aimed at stabilizing blood sugar and supporting weight management.

3. Resistant Starch (RS):
As the name suggests, resistant starch resists digestion in the small intestine. Instead, it travels to the large intestine, where it is fermented by gut bacteria. This process is slower and yields beneficial short-chain fatty acids like butyrate, which support gut health, enhance satiety, and help regulate blood sugar.

Resistant starch is widely regarded as the most beneficial type of starch and functions in many ways like dietary fiber.

The Retrogradation Process of Starch and Its Effect on Starch Composition

In starchy foods that are cooked or baked, such as bread, potatoes, pasta, or rice, a process called starch retrogradation begins the moment the food cools, and continues during storage.

Retrogradation alters the structure of gelatinized starches, leading to the formation of RS3 (resistant starch type 3). As a result, the concentration of rapidly digestible starch (RDS) tends to decrease, while the concentrations of resistant starch (RS), and to a lesser extent slowly digestible starch (SDS), increase.

Important Clarification on Starch Types

Rapidly digested starch (RDS) is not inherently “bad.” It serves an important role in providing immediate energy, and is essential in certain contexts, for example, before intense physical activity.

However, for long-term health, weight control, and blood sugar stability, a diet richer in SDS and RS starches is generally more beneficial.

While dietary guidelines from health authorities don’t explicitly differentiate between starch types, they strongly recommend:

• Increasing intake of whole grains, legumes, and vegetables.
• Reducing consumption of ultra-processed, refined-flour products.

These recommendations implicitly favor foods higher in SDS and RS and lower in RDS, aligning with current research, which consistently highlights the health benefits of slowly digested and resistant starches.

Study #1: The Effect of Fermentation Time on the Properties of Classic Neapolitan Pizza

This study, conducted in Naples and published on March 23, examined how different fermentation times affect the physical and chemical properties of classic Neapolitan pizza. Two key aspects are especially relevant to our discussion:

• The concentration and composition of starches – providing insight into starch breakdown over time.
• The concentration of free amino groups – indicating the extent of protein breakdown in the dough.

Study Overview

Here are the essential characteristics of the study:

• Six dough batches were prepared with different fermentation times: 0 (no fermentation), 4, 8, 16, 24, and 48 hours.
• All doughs shared the same formula: 62.5% water, 3.1% salt, and 0.066% fresh yeast.
• Fermentation was done at 22°C (72°F).
• Each pizza was baked in a wood-fired oven at approximately 485°C (900°F) for 60 seconds.

The researchers analyzed both unbaked doughs and baked pizzas, measuring:

• Starch profiles:
  • RDS (Rapidly digested starch)
  • SDS (Slowly digested starch)
  • RS (Resistant starch)
  • TS (Total Starch = RDS + SDS + RS)
  • SDRI (Starch Digestion Rate Index – see explanation below)
• RAG (Rapidly Available Glucose) – used as an indicator or predictor of the potential glycemic index.
• Free amino group concentration — an indirect measure of protein degradation during fermentation.

How “Digestibility” Was Defined in the Study

To estimate digestibility, the researchers used an in vitro digestion process and measured starch breakdown using a Megazyme commercial assay kit. The classification criteria for the starch types were:

• RDS: Starch hydrolyzed (broken down) within 20 minutes
• SDS: Starch hydrolyzed between 20 and 120 minutes
• RS: Starch not hydrolyzed after 4 hours

The main metric the researchers used to define “digestibility” was the SDRI (Starch Digestion Rate Index):

SDRI = RDS / TS
(i.e., the proportion of total starch that is rapidly digestible).

A higher SDRI suggests a larger share of starch is rapidly digestible and, therefore, that the dough may be broken down more quickly in the body (i.e., “more digestible”.)

It’s important to clarify that in this study, “digestibility” refers only to the rate of enzymatic starch breakdown – not to broader nutritional or metabolic outcomes. The study does not evaluate health benefits, glucose absorption in the body, or overall glycemic response.

In summary: This study provides useful lab-based data about how fermentation time affects starch breakdown. However, its measure of “digestibility” should be interpreted in context – it reflects chemical digestion speed, not how the body experiences or benefits from the food.

Limitations of the Study

There are three important limitations or “problems” in this study that should be noted:

1. The doughs were prepared and baked by an external food scientist, Dr. Aniello Falciano, rather than a professional pizza chef. While this is less significant during the dough preparation stage, it becomes critical during the baking process – especially for Neapolitan pizza, which bakes in just 60 seconds. Any slight variation in the baking method, including the pizza’s position in the oven, the temperature of the stone and oven cavity, proximity to the flames, and baking time (even a few seconds) – could have affected the experiment’s results.
2. All doughs contained the same amount of yeast (0.066%). This choice by the researchers, likely made to maintain a consistent dough formulation and fermentation environment, is problematic. Different fermentation times, particularly at room temperature, require different yeast quantities.
   A yeast level of 0.066% at 22°C is suited for around 24 hours of fermentation; This means the doughs that fermented for only 4-8 hours were likely under-fermented, while the dough that fermented for 48 hours likely reached over-fermentation, as evidenced by the dough images included in the study.
3. The researchers used Caputo Chef flour, which, like most Italian flours, has low enzymatic activity, which means it contains relatively low levels of amylase enzymes compared to other flours. This choice of flour significantly affects the rate of starch breakdown during fermentation, and thus influences the outcomes of the experiment.

These limitations highlight the methodological challenges in conducting studies of this nature, particularly when trying to draw broad or definitive conclusions from them.

Results, Conclusions, and Discussion

Below are the study results most relevant to our topic: the composition of starches in each dough, and the concentration of free amino groups.

The study highlights three key findings:

1. Baking significantly alters starch composition. After baking, the concentration of RDS increased sharply, while SDS and RS starches were reduced to nearly undetectable levels. This transformation is consistent with the effects of high heat, which gelatinizes and degrades more resistant forms of starch.
2. The dough’s digestibility index (SDRI) peaked after approximately 8 hours of fermentation.
   This suggests that at this point, the dough is at its most “digestible” state based on starch composition.
3. The concentration of free amino groups in the baked pizza also peaked after about 8 hours of fermentation.

1. The Effect of Baking on the Proportions of Starch Types in Dough

As observed in the study, baking is the stage at which the vast majority of starches are converted into RDS starch. In all samples, baking caused a substantial increase in RDS, while the concentrations of SDS and RS dropped drastically to near zero.

This transformation results from starch gelatinization, a process that occurs during baking when heat causes starch granules to absorb water, swell, and rupture. This structural change makes starch molecules significantly more accessible to amylase enzymes, accelerating their breakdown into simpler sugars.

For the baked pizzas, the data shows that:

• Up to about 16 hours of fermentation, longer fermentation correlates with higher RDS and lower SDS concentrations (especially between 4-8 hours).
• This implies that during fermentation, more SDS starches were structurally altered, allowing them to break down more readily during baking.

Notably, RS starch levels fell to nearly zero across all baked pizzas, regardless of fermentation duration. Even dough that wasn’t fermented at all showed this outcome.

2. The SDRI Index Peaked After 8 Hours of Fermentation

This is arguably the most meaningful takeaway from the study with respect to fermentation and digestibility.

• The Starch Digestion Rate Index (SDRI), a ratio of RDS to total starch (TS), peaked at ~96.91 after 8 hours of fermentation.
• This indicates that, based on this metric, the dough was most “digestible” at this point.

Beyond 8 hours, the SDRI began to decline slightly, suggesting diminishing returns (or even regression) in digestibility as fermentation continued.

3. The Concentration of Free Amino Groups Peaked After About 8 Hours

Free amino groups (peptides and amino acids) form when protease enzymes break down proteins in the dough. A higher concentration of free amino groups implies more advanced protein breakdown.

The study shows that in baked pizzas, free amino groups peaked after around 8 hours of fermentation, with an increase of ~15% compared to unfermented dough.

Summary and Additional Comments

The study’s findings suggest that fermentation time positively affects the ‘digestibility’ of pizza – defined by the researchers as the extent to which starch and protein are broken down during fermentation, ultimately influencing their concentration in the baked pizza.

According to the results, an 8-hour fermentation at 22 °C (72 °F) yielded the highest digestibility, as reflected the peak SDRI index and free amino groups.

Notably, even a relatively short fermentation of 4 hours significantly improved the SDRI: from 63 in unfermented dough, to 81.4 after 4 hours. After 8 hours, the SDRI reached 96.9. Beyond this point, the upward trend flattened, and further fermentation did not lead to additional gains.

In conclusion: the study supports the idea that fermentation enhances the “digestibility” of starches and proteins in pizza dough – as measured under laboratory conditions.

From both a starch and protein breakdown perspective, the optimal fermentation time (in this specific study) appears to be around 8 hours at room temperature. Beyond that, benefits either plateau or begin to reverse, and the dough’s structural integrity may also deteriorate.

That said, a few important caveats should be kept in mind, some of which were addressed earlier:

• RDS as a digestibility indicator: While the study defined ‘digestibility’ based on a higher concentration of RDS, this isn’t necessarily beneficial. In most contexts, particularly regarding blood sugar response, it can actually be undesirable.
• Quantitative vs. qualitative analysis: The study assessed digestibility by measuring the chemical breakdown of starches and proteins. However, this doesn’t necessarily reflect how bioavailable or beneficial they are to the human body.
• In vitro limitations: Laboratory measurements of digestion don’t always translate to real-world human digestion. Increased levels of RDS or free amino groups in vitro may not have the same physiological effect when consumed.
• Fermentation temperature: The study used 22 °C (72 °F) as the fermentation temperature. At lower temperatures, such as in cold fermentation, amylase activity drops significantly by a factor of 6-8 – which slows starch breakdown. Conversely, At higher temperatures, breakdown occurs more rapidly.
• Flour choice: The study used a flour with low enzymatic (amylase) activity (Caputo Chef). Flours with higher enzymatic activity will accelerate starch breakdown. Using such flours could shorten the fermentation time needed to reach similar results.

Study #2: The Effect of Fermentation Times and the Use of Preferment (Biga) on the Nutritional Values of Pizza Pinsa Romana

This Italian study, published in June 2023, examined how fermentation time and the use of a biga preferment affect the digestibility and nutritional profile of pizza pinsa romana, a rectangular, Roman-style flatbread pizza.

The researchers analyzed six dough variants:

• Three doughs with yeast-only biga, fermented for 24, 48, and 72 hours.
• One dough with yeast + sourdough biga, fermented for a total of 48 hours.
• One dough with yeast-only biga, with sourdough added only to the final dough (not to the biga), fermented for a total 48 hours.
• A control dough, fermented for 3.5 hours with no biga or sourdough.

After baking, each pizza underwent simulated in vitro digestion. Researchers then measured various nutritional and digestibility indices in the digested samples.

Study Overview

This study tested six dough formulations:

1. Biga dough, fermented for 24 hours.
2. Biga dough, fermented for 48 hours.
3. Biga dough, fermented for 72 hours.
4. Biga dough with 9% sourdough (added to the biga), fermented for 48 hours.
5. Biga dough with 40% sourdough added only to the final dough, not to the biga, fermented for 48 hours.
6. Direct dough (no biga or sourdough), fermented for 3.5 hours.

Here are the key Conditions and methodology of the study:

• The fermentation times refer only to the biga. For example, ’24 hours of fermentation’ means that the biga was fermented for 24 hours, not including the fermentation time of the final dough (as detailed below).
• All bigas were fermented at 16°C (61°F).
• After mixing with the remaining ingredients, all the final doughs (except the control one) were fermented for an additional 3.5 hours at 24°C.
• Dough #6 (control/direct dough) was fermented only for 3.5 hours at 24°C.
• All pizzas were baked at 330°C for 3 minutes.
• All doughs contained yeast, though the specific amount was not disclosed. Doughs #4 and #5 also included sourdough to assess its impact on nutritional quality.
• The biga accounted for 100% of the flour in the final doughs – meaning the entire starch and protein content of the dough underwent the biga fermentation process.

Moving forward, the focus will be on comparing the doughs without sourdough:

• Direct dough (short fermentation, no biga), vs
• Biga doughs fermented for 24, 48, and 72 hours

This comparison will clarify the effect of fermentation time alone, via biga, on the digestibility, nutritional profile, and potential taste of the baked pizzas.

How “Digestibility” Was Defined in This Study

This study used a more comprehensive and physiological definition of digestibility compared to the first study.

Whereas the previous study focused on chemical degradation of starch and protein (i.e., how much of each was broken down), this study aimed to simulate actual digestion in the human body, including the oral, gastric, and intestinal phases.

Rather than just measuring the extent of degraded starch or protein, the researchers measured the bioavailability of their final digestion products.

Each baked pizza underwent in vitro digestion simulating the mouth, stomach, and small intestine phases of human digestion. The following indices were measured:

• IVPD (In Vitro Protein Digestibility): Measures the degree to which proteins were broken down into free amino groups available for absorption.
• EAA (Essential Amino Acid Index): Assesses the quality of the protein by calculating the proportion of essential amino acids.
• NI (Nutritional Index): A combined index of IVPD and EAA, reflecting both protein digestibility and nutritional value.
• Glucose: Indicates the degree of starch breakdown into absorbable glucose molecules.
  Peptides: Intermediate protein breakdown products, also absorbable by the human body.
• Other measured factors: Predicted glycemic index (pGI), lactic & acetic acid concentration, resistant starch (RS), dietary fiber.
  

In short: this study assessed what the body could actually absorb, not just what broke down chemically. It provides a more realistic view of nutritional “digestibility” in baked pizza as it is consumed.

Results, Conclusions, and Discussion

Here is a summary of the relevant study results:

Below is a summary of the study’s findings (focusing specifically on the doughs that did not contain sourdough):

• No significant difference in protein breakdown (IVPD):
  According to the IVPD index, there were no substantial differences in the amount of protein degraded between the short-fermented control dough and the biga-fermented doughs.
• No major improvement in protein nutritional quality up to 48 hours:
  Up to 48 hours of biga fermentation, the changes in the NI index were marginal. The nutritional profile of the proteins (as measured by the NI index) remained essentially the same between the short-fermented dough and the 24 and 48-hour biga doughs.
• A meaningful improvement occurred only at 72 hours of fermentation:
  Among the doughs without sourdough, only the 72-hour biga showed a notable increase in the NI index – from 2.86 to 3.6 (an improvement of ~30%). This suggests an enhancement in protein quality only after extended fermentation.
• No difference in predicted glycemic index (pGI):
  All doughs showed similar pGI values, except the biga dough that included sourdough, which had a ~10% lower pGI.
• Peptide concentration increased slightly after long(er) fermentation:
  There was an increase in post-digestion peptide levels between the 48 and 72-hour doughs, but not between the short-fermented dough and the 24-hour biga. Doughs containing sourdough showed significantly higher peptide concentrations, consistent with the IVPD and NI results.
• Glucose availability increased with fermentation time, but not consistently:
  Glucose concentration after digestion generally rose as fermentation time increased, though not in a linear way. There was a rise from the short-fermented dough to the 24-hour biga, a dip at 48 hours, and a significant increase at 72 hours. These fluctuations are likely due to a complex interplay of starch breakdown, microbial sugar consumption, enzymatic activity, and changes in dough structure.
• Longer fermentation does not guarantee higher glucose availability:
  While extended fermentation can enhance glucose availability, the relationship is not directly proportional. More fermentation time does not necessarily result in more glucose in the final baked product.
• No change in resistant starch (RS) concentration:
  All doughs had identical levels of resistant starch after digestion, as expected. RS is broken down only in the large intestine, which was not simulated in this study.

Conclusion:

Even under what might be considered “ideal” conditions for optimal digestibility in yeast-leavned dough – the observed improvements in protein and starch digestibility were small, inconsistent, and mostly not statistically significant. Only the addition of sourdough (either in the biga or the final dough) resulted in meaningful changes, but that’s outside the scope of this article.

In summary: this study reinforces the conclusion that long fermentation of yeast-only dough does not necessarily enhance its nutritional value or digestibility in any practically significant way.

Factors Affecting (and Not Affecting) the Actual “Digestibility” of Pizza

Now that we’ve established that a long fermentation has only a limited effect on dough and doesn’t necessarily make it more “digestible” or healthy, what does influence pizza’s “digestibility” or the feeling we experience after eating it?

In Italy, pizzas are often judged by how much they “sit in the stomach” after a meal. In other words, “digestibility” is commonly understood as how quickly a pizza is digested (an idea reflected in the first study discussed above.)

In the following sections, we’ll adopt this interpretation and explore the different aspects of pizza that may affect how “quickly” it digests, and whether it causes a feeling of “heaviness” or bloating – assuming that dough fermentation time is not a major factor.

Factors That Affect Digestion Speed and the Feeling of “Heaviness” After Eating Pizza

These are the primary factors that influence how quickly pizza is digested and how “heavy” it feels afterward:

1. How much pizza you eat.
2. The amount of cheese, sauce, and toppings used.
3. The type of cheese used.
4. How the pizza is baked.
5. General factors that affect digestion (of any food).

1. How Much Pizza You Eat

This point is straightforward: the more pizza you eat, and therefore the more dough, cheese, sauce, and toppings you consume – the greater the load on your digestive system, and the higher the likelihood of feeling “heavy” after the meal.

But not all pizzas are created equal. A “pizza” or a “slice” can contain very different amounts of dough, sauce, cheese, and toppings, which will directly affect how filling or heavy it feels.

For example, take two pizzas of the same size (diameter): 30 cm (12″):

• One is a thin pizza made with 270 grams of dough and a modest amount of sauce and cheese.
• The other is a thick pizza made with 330 grams of dough and generous amounts of cheese and sauce.

Even though both pizzas are the same size, the second one is much more “heavy” to digest, simply because it contains more food overall.

2. The Amount of Cheese, Sauce, and Toppings

The amount of cheese, sauce, and toppings on a pizza has a major influence on its digestibility. Generally, the more you add, the “heavier” the pizza becomes.

Cheese, in particular, plays a central role – both in quantity and in type (which will be addressed in the next section). More cheese, or cheese with certain properties, increases the digestive load and can make the pizza feel heavier.

The type of toppings also matters. Animal proteins are generally digested more slowly than plant-based ones, so meat toppings like pepperoni or sausage (which also contain a significant amount of fat) naturally make the pizza “harder” to digest. The more of these toppings you add, the stronger the effect.

For most people, the amount of tomato sauce doesn’t greatly impact digestion. However, those with chronic stomach issues (such as gastritis or GERD) may find that large amounts of tomato sauce, which is inherently acidic, can worsen symptoms or slow digestion.

3. The Type of Cheese Used

This is likely the factor with the greatest impact on the digestibility of a [cheese] pizza.

Cheese consists mainly of two nutritional components:

1. Fat – Most cheeses used on pizza contain between 18% and 30% fat.
2. Protein, primarily casein – Casein accounts for about 80% of the proteins in milk.

Fat slows down stomach motility, meaning food remains in the stomach longer before passing into the small intestine. This delay in gastric emptying slows the digestion of the entire meal, including the dough, sauce, and toppings.

In short: A higher fat content in the cheese slows down overall digestion, which can increase the feeling of fullness or ‘heaviness’ after eating.

Casein, upon reaching the stomach, tends to coagulate and form a gel-like structure. Like fat, this slows gastric emptying and digestion. In practical terms, a higher concentration of casein can prolong satiety and may contribute to sensations of bloating or heaviness.

In summary: the higher the fat and protein content (%) of the cheese used, the slower the digestion of the pizza – both in theory and in practice – resulting in a more pronounced feeling of post-meal “heaviness”.

4. How the Pizza Is Baked

The baking process has a significant impact on the digestibility of pizza.

Under-baked dough tends to retain more ungelatinized starch – meaning less rapidly digestible starch (RDS) – and may also contain fewer peptides due to incomplete protein breakdown. This can slow down digestion and contribute to sensations of heaviness or bloating.

Over-baking, on the other hand, particularly when the dough or cheese becomes burned or heavily charred, can lead to the formation of undesirable compounds. These include acrylamide (mainly in dough) and polycyclic aromatic hydrocarbons (PAHs), which are generated when proteins and fats are burned. Such compounds are poorly absorbed by our body, may burden the digestive system, and can even reduce the overall nutritional value of the pizza.

5. General Factors That Affect Digestion (of Any Food)

In addition to the factors specific to pizza, several general aspects can affect digestion and apply to all types of food:

1. Salt (sodium) content
2. What (and how much) you drink with your food
3. How thoroughly you chew

Salt (Sodium) Content

Salt stimulates the secretion of stomach acid, which may aid in breaking down proteins. However, excessive salt can cause a sense of heaviness, bloating, or discomfort.

In pizza, cheese is typically the largest contributor of sodium, followed by the sauce and dough.

While salt doesn’t directly inhibit digestion, high concentrations can negatively impact the overall digestive experience, whether by irritating the digestive system or indirectly affecting it (e.g., increasing thirst or reducing intestinal activity). Balancing salt levels can help support more comfortable and efficient digestion.

What (and How Much) You Drink With Your Food

Fluid intake during meals can influence feelings of heaviness and overall digestion. Moderate consumption of water while eating may support digestion, but drinking large quantities, especially of carbonated, sweetened, or alcoholic beverages – can overburden the stomach, cause bloating, and slow down the digestive process.

To promote optimal digestion, it’s best to sip water in small amounts during the meal, and avoid drinking excessive amounts (of any beverage) during or immediately after eating.

How Thoroughly You Chew

Chewing is the first (and often underestimated) step in digestion. It plays a critical role in both the mechanical and chemical breakdown of food:

• Saliva contains amylase (specifically salivary amylase), which begins breaking down starches during chewing.
• Thorough chewing breaks food into smaller particles, increasing surface area and allowing digestive enzymes to work more efficiently throughout the digestive tract.
• Chewing was also found to have other digestive benefits, such as promoting the release of satiety hormones, stimulating gastric juice production, and supporting smoother overall digestion.

On the other hand, chewing too quickly or insufficiently forces the stomach and intestines to “compensate”, potentially leading to slower, less effective digestion, and symptoms like bloating, gas, abdominal discomfort, and reduced nutrient absorption.

In summary: thoroughly chewing your food enhances the entire digestive process.

Other Myths Related to Pizza and Digestibility

Beyond the myth we’ve already debunked – that long-fermented dough is inherently more digestible – several other popular myths persist. In the following sections, we’ll explore a few of the most common ones:

1. Does the type of flour or wheat impact digestibility?
2. Can dough hydration levels make pizza easier to digest?
3. Are Italian pizzas inherently more digestible?

Does the Type of Flour or Wheat Affect Digestibility?

A common claim, especially in Europe and particularly in Italy, is that flours milled from European wheat are easier to digest than those from North America. This belief usually rests on two main arguments:

1. Lower protein content: Much of the wheat grown in Europe, particularly in Italy and France, is soft wheat, which naturally has lower protein (gluten) content than the hard wheat varieties commonly grown in North America.
2. Less “engineered” wheat: It’s often said that American wheat has been genetically modified or selectively bred to a greater extent, making it less digestible than the more “natural” European wheat.

Let’s take a closer look at each claim.

Protein Content and Digestibility

In theory, lower-protein flours could be easier to digest. With less protein to break down, the digestive system may have less work to do.

However, this logic doesn’t hold up well in real-world pizza making.

For starters, most pizza flours available today, including many Italian ones, are high in protein, regardless of origin.

Furthermore, even when comparing flours with different protein levels – say 10% vs. 13% – the final effect on digestion is likely minimal. Protein content alone doesn’t determine how much protein remains after fermentation or how the body will respond to it – the fermentation process itself plays a far more significant role.

In fact, what matters more is how the flour is matched to the fermentation time:

• High-protein flours are typically used for long fermentations, since their stronger gluten structure holds up better over time.
• Lower-protein flours are more suited to short fermentation.

In both cases, the fermentation process breaks down some of the proteins, and the end result may be quite similar – especially when the fermentation is properly tailored to the flour’s properties.

In summary: While the protein content of flour can influence that of the final baked good, its effect on digestion is neither straightforward nor likely significant in practice.

The “Less Engineered” Wheat Argument

As for the idea that European wheat is less modified or more “natural,” the truth is more complex.

Rather than debating the merits of modern wheat breeding, it’s important to highlight one key fact: many European flours – especially Italian ones – contain a significant portion of North American wheat.

For example, well-known Italian mills like Caputo rely heavily on imported hard wheat from the U.S. and Canada to meet the demands of modern baking. Much of the wheat grown in Italy is soft wheat with low protein content, which performs poorly on its own in applications such as pizza or bread dough.

To produce flour suitable for these modern baking needs (e.g. stronger, higher-protein flour), mills blend high-protein North American wheat with the lower-protein local wheat.

In practice, this means that many Italian flours are hybrids: a mix of local and imported wheat. So even if you think you’re using 100% European flour, there’s a good chance it contains a substantial amount of North American wheat.

In summary: Many strong European flours, especially Italian ones, contain a notable amount of North American wheat. This fact undercuts the idea that European/Italian flours are inherently “more digestible”; At best, the claim is misleading; at worst, it’s entirely false.

Does Dough Hydration Affect Pizza Digestibility?

Another widespread belief is that dough hydration – the water content of the dough – impacts how digestible a pizza is.

In theory, higher hydration means more water and less flour in the dough, which could affect the nutritional composition of the dough and baked pizza.

Since flour contains the bulk of the carbohydrates (starch) and proteins (gluten), reducing its proportion might seem to make the dough “easier” to digest. But how significant is this difference in practical terms?

First, it’s important to clarify that hydration is expressed as a percentage relative to the amount of flour (in baker’s percentages), not in relation to the total dough weight.

Let’s break it down with a clear example:

Consider two doughs with different hydration levels – one at 60%, the other at 80%, each with a total dough weight of 300 grams (composed only of flour and water):

• 60% hydration: 187g flour, 113g water
• 80% hydration: 167g flour, 133g water

At first glance, there’s a 20-gram difference in flour between the two doughs. That translates to:

• Flour as a percentage of total dough:
  • 60% hydration: 62.3% (187 ÷ 300)
  • 80% hydration: 55.6% (167 ÷ 300)

Despite a 20% difference in hydration, the actual difference in flour content is just under 7%.

Since flour is roughly 75% carbohydrates, that results in about a 5% difference in carbohydrate content. If the flour has 13% protein, the difference in protein content is about 0.9%.

Put into practical terms: for a 300g pizza dough, you’re looking at a difference of about 15 grams of carbohydrates and 2.6 grams of protein between the two doughs.

So, Does It Matter?

From a “digestibility” standpoint, this difference is insignificant. Even in extreme cases, like eating a whole pizza by yourself – the variation in flour (and therefore starch and protein content) caused by hydration is too small to noticeably affect how your body processes the pizza.

To conclude: The impact of dough hydration on digestibility – via changes in flour content – is negligible, even at the extremes.

Are Italian Pizzas “More Digestible”?

It’s common to hear Italian pizzaiolos, and even Italians in general, claim that Italian pizzas are “more digestible.” This assertion often serves as a marketing tool, positioning Italian pizza as superior in quality and “easier on the stomach” compared to pizza from other parts of the world.

This belief isn’t limited to Italians. Tourists from around the world often praise the pizzas they enjoyed in Italy for their “lightness” and being “easier to digest” compared to those from their home countries.

But is there any truth to this? Are Italian pizzas actually more digestible?

Typical Characteristics of Italian Pizza

To answer this question, we first need to understand the general characteristics of a traditional Italian pizza, whether Neapolitan, Roman, or others:

1. Less Dough: Italian pizzas are usually thinner and smaller, meaning there’s simply less dough overall compared to thicker and bigger styles elsewhere.
2. Less Cheese and Sauce:  Compared to their American counterparts, Italian pizzas typically have far less cheese and sauce. For example, a Neapolitan pizza of the same size will often contain 1.5 to 3 times less cheese and sauce than a typical American pizza.
3. Lower-Fat Cheese: Italian pizzas, especially Neapolitan ones, often use fresh mozzarella, which contains less fat than the low-moisture mozzarella common in the U.S. (about 18% vs. 24%). As discussed earlier, fat content can significantly affect how “heavy” or “digestible” a pizza feels.
4. Artisan Quality: Many pizzerias in Italy, particularly the well-regarded ones that attract tourists, serve pizzas made with a strong emphasis on craftsmanship, ingredient quality, and process. These stand in sharp contrast to the industrial, chain-style pizzas (e.g., Domino’s, Pizza Hut) that are widespread in many countries, but are virtually nonexistent in Italy.

These characteristics help explain why Italian pizzas are often perceived as easier to digest: They tend to be higher in quality, more balanced, and lighter in overall ingredient quantity – especially when compared to chain or fast-food pizzas.

So, is this perception a complete myth? Not entirely. Many Italian pizzas do possess traits that can make them, in theory, easier to digest. However, and this is key, their digestibility has little to do with the dough’s fermentation time – instead, it’s largely a result of the pizza’s overall composition and preparation.

Why Do Tourists Often Feel Italian Pizzas Are “Lighter”?

And what about the common claims from tourists who insist that the pizzas they had in Italy felt noticeably “lighter” than those back home? Is there an objective basis for this perception, or is it all in their heads?

There are several plausible explanations for this phenomenon:

• Psychological Factors: Being on vacation generally means less stress and a better mood – both of which influence digestion. When relaxed and happy, the body digests food more efficiently. This psychological state may lead to a subjective (but genuine) feeling that the food is easier to digest.
• Increased Physical Activity: Tourists tend to walk much more during trips than in their normal routines. Numerous studies show that light physical activity helps digestion. For example, walking after a meal aids digestion by promoting faster gastric emptying and reducing discomfort. So the vacation lifestyle itself can contribute to a lighter feeling after meals.
• Artisan vs. Industrial Pizza: In many countries, people are used to industrial, chain-made pizzas. When they visit Italy and experience a high-quality, artisan-made pizza, the difference in quality alone can influence how “digestible” the meal feels.
• The Real Differences in Italian Pizza: As discussed above, Italian pizzas often include less dough, less cheese and sauce, and use lower-fat ingredients. These are tangible differences that can, in practice, make the meal feel lighter – even if only modestly so from a nutritional standpoint.

Final Thoughts

In theory, Italian pizzas can be more digestible – but not because of long fermentation or mysterious flour properties. It’s primarily because they tend to use less dough, sauce, and cheese, often opt for lower-fat ingredients, and are crafted with more care and quality control than their industrial counterparts.

However, these qualities aren’t exclusive to Italian pizzas – they’re simply more common in Italy. The improved perception of digestibility may also stem from other factors, like vacation-related mood and activity, that enhance the overall eating (and digestive) experience.

So while the myth isn’t entirely baseless, it’s not universal truth either. Like most things in food culture, it’s a mix of real differences, subjective experiences, and good storytelling.

Bonus Discussion: Gluten Sensitivity, FODMAPs, and Digestibility

FODMAPs, short for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, are a group of short-chain carbohydrates that are poorly absorbed in the small intestine. Like resistant starch and dietary fiber, FODMAPs pass into the large intestine, where they are fermented by gut bacteria.

For most healthy individuals, FODMAPs are not only harmless, but actually beneficial – much like fiber and resistant starch, they support gut health by feeding the gut microbiome.

However, in people with FODMAP sensitivity, especially those with irritable bowel syndrome (IBS), this fermentation process by gut bacteria can trigger unpleasant digestive symptoms such as bloating, gas, abdominal pain, diarrhea, or constipation.

One specific type of FODMAP is fructans, a group of oligosaccharides made up of fructose molecules. Fructans are present in relatively high amounts in wheat and wheat-based products, such as bread, pasta, cereals, and essentially all flour-based baked goods. In fact, wheat is the primary source of fructans in the typical Western diet.

Because the symptoms of FODMAP sensitivity overlap with those of celiac disease, many people mistakenly believe they have “gluten sensitivity”, while in reality, the issue may not be gluten at all – but rather fructans.

Importantly, fructans, like starch, are broken down during the dough’s fermentation process. In the next section, we’ll briefly review two studies that explore how fermentation time affects fructan content in dough, and whether extended fermentation might reduce symptoms for individuals with FODMAP sensitivity.

Studies on the Effect of Dough Fermentation on Fructan Concentration

The following three studies investigated how dough fermentation influences the concentration of fructans – one of the main FODMAPs found in wheat-based products.

Study #1

The first study (Fructans, Water-Soluble Fibre and Fermentable Sugars in Bread and Pasta Made with Ancient and Modern Wheat) examined the impact of yeast-leavened fermentation on fructan content in breads made from different types of flour: modern white wheat flour, and wholemeal flours from ancient grains (Emmer and Khorasan). For our purposes, the focus is on the breads made from regular white flour.

The researchers compared a control group – doughs that weren’t fermented at all –  to doughs fermented for 3 hours at 35 °C (95 °F). All doughs contained 1.2% dry yeast. Fructan concentrations were measured both in the dough (before baking) and in the final bread.

The findings were significant: dough made with white flour saw a 70% reduction in fructan content after 3 hours of fermentation – dropping from around 1% (1 gram per 100 grams of flour) to under 0.3%, in both the fermented dough and baked bread.

Conclusion: A relatively short, 3-hour fermentation using a high yeast amount and a warm temperature (35 °C) was sufficient to break down most of the fructans in white flour dough.

When combined with data on average daily fructan intake (as reported in the study), the findings suggest that longer fermentation (depending on temperature and yeast quantity) can significantly improve dough digestibility for individuals with FODMAP sensitivity, potentially reducing or even eliminating symptoms.

Study #2

The second study (Wheat and the Irritable Bowel Syndrome: FODMAP Levels of Modern and Ancient Species and Their Retention During Bread Making) also examined how different fermentation times affect FODMAP levels in dough, with a particular focus on fructans, and to a lesser extent, raffinose (another FODMAP found in low levels in wheat).

As in the previous study, various wheat flours were tested, including modern, “regular” wheat.

The doughs were fermented at 30 °C (86 °F) for three different durations: 1 hour, 2.5 hours, and 4.5 hours, each containing 4.16% fresh yeast. After fermentation, they were baked and analyzed for FODMAP concentration.

The results echoed those of the first study: fructan concentrations dropped by about 70% after 2.5 hours, and by about 90% after 4.5 hours of fermentation in the modern wheat dough.

In summary: These findings reinforce that extended fermentation (depending on temperature) can significantly reduce the fructan content in yeast-leavened dough.

Study #3: Fructan Breakdown in Neapolitan Pizza Dough

The third study (Impact of Microbial Leavening Agents and Fermentation Time on the In Vitro Digestibility of Neapolitan Pizza), examined how different fermentation durations affect fructan concentration in classic Neapolitan pizza dough. Six yeast-leavened doughs were tested, fermented for 0, 4, 8, 16, 24, and 48 hours.

All doughs were fermented at a room temperature of 22 °C (72 °F) – a setting much closer to typical home fermentation conditions. Each dough contained the same amount of fresh yeast: 0.066%.

The results showed a more modest reduction in fructan levels compared to the previous studies: only ~20% after 8 hours of fermentation, with a gradual, linear decrease reaching ~73% after 48 hours.

This slower breakdown is likely due to the much lower yeast content and lower fermentation temperature – both of which significantly slow enzyme activity and require more time for substantial fructan degradation.

In summary: This study reinforces the findings of the previous two – longer fermentation can significantly reduce fructan levels in dough. However, the reduction took longer here, likely due to the lower temperature and very small yeast amount used.

Key Takeaways from the Three Studies

The above studies demonstrate that longer fermentation can break down most of the fructans in the dough, potentially leading to significant symptom improvement in individuals sensitive to FODMAPs.

Exactly how ‘long’ the fermentation needs to be depends heavily on both the fermentation temperature and the amount of yeast – higher values for either accelerate fructan breakdown.

For individuals with FODMAP sensitivity or IBS, switching from industrial bread (which typically undergoes minimal fermentation) to artisanal bread that is fermented longer, could significantly improve digestive tolerance.

Concluding Thoughts on Dough Fermentation and Digestibility

This was a long article, with a lot to digest (pun intended), and yet we’ve only scratched the surface of the vast complexity of the human digestive system.

Still, the topics we explored offer a solid foundation for understanding an important takeaway: While fermentation does trigger biochemical changes in the dough that could theoretically improve its digestibility, the real-world effect is questionable; And even if such an effect exists, it appears to peak after just a few hours of fermentation at room temperature.*

Long fermentation undeniably offers benefits, particularly in enhancing texture and developing deeper, more complex flavors, and it is highly recommended for those who want to maximize the quality of their pizza or bread. However, despite the widespread belief that long fermentation makes dough more digestible, for the average healthy person, fermentation time has little to no measurable impact on digestibility – whether judged by nutritional value or by the actual speed or ease of digestion.

Conversely, many other factors discussed throughout the article – ranging from ingredient choice to psychological and cultural influences – can meaningfully impact how “digestible” a pizza is (or feels). So, if your goal is to make a pizza that feels “easier on the stomach”, you’re better off focusing on those variables (or at least being aware of them), rather than obsessing over fermentation time.

So the next time someone tells you that long-fermented pizza or bread is ‘healthier’ or ‘easier to digest,’ it’s worth asking: for whom, and by what standard? (Or, you can just send them this article.)