Soup & Smile — Turkish Tarhana Soup

Research & tradition

The Science Behind Tarhana

An old food, studied with modern science.

Tarhana has been made for generations — long before anyone measured its microbes, amino acids or aroma compounds in a laboratory.

Today, food scientists are beginning to explain what generations of cooks learned through experience: fermentation changes food.

Here, we explore what researchers have actually found about tarhana — and just as importantly, what science does not yet know.

No miracle claims. No wellness buzzwords.
Just the research.

Our process

Time is an ingredient.

Our bowl begins 21 days before we serve it.

Our tarhana follows a family method that gives the dough approximately 21 days to ferment, with regular mixing throughout the process.

We didn't choose 21 days because a scientific paper told us to.

We inherited it.

But modern research gives us a fascinating way to understand why time matters.

Studies comparing different tarhana fermentation periods — including 7, 14 and 21 days — have found that fermentation length can influence microbiological and sensory characteristics.

Other research has shown that tarhana's volatile aroma profile continues to develop as fermentation progresses.

What research tells us

Fermentation time matters. Researchers have observed changes in sensory, microbiological and aromatic characteristics as tarhana fermentation progresses.

What it doesn't tell us

Research does not establish that 21 days is universally healthier or scientifically superior to every other fermentation period.

“Time is an ingredient.”

In the dough

Fermentation is alive with change.

  1. Milk
  2. Yogurt
  3. Dough
  4. Fermentation
  5. Drying
  6. Soup

Traditional tarhana fermentation involves communities of lactic acid bacteria and yeasts.

As they interact with the ingredients, researchers observe changes in acidity, microbial populations, aroma compounds and parts of the food's chemical composition.

Even two tarhanas can ferment differently.

Research comparing homemade and commercially produced tarhana found different lactic-acid-bacteria communities between the two production environments.

Same name.
Different process.
Different microbial ecosystem.

Food chemistry

Fermentation changes the food.

Amino acids

Fermentation changes tarhana's free amino-acid profile.

A 2005 study followed free amino acids through fermentation, drying and storage and found substantial changes during the process.

Research contextThese measurements describe changes in the food itself. They do not mean that eating tarhana increases a person's amino-acid levels by the same percentages reported in the study.

Erbaş et al., 2005 — The effect of fermentation and storage on free amino acids of tarhana. International Journal of Food Sciences and Nutrition

PubMed ↗

Phytic acid

Fermentation changes naturally occurring compounds in grains and legumes.

Researchers have studied how tarhana fermentation and formulation affect phytic acid, a naturally occurring compound found in many grains and legumes.

Research contextA reduction in phytic acid measured in a food does not by itself prove increased mineral absorption in people.

Ertaş, 2018 — Effects of Baker's Yeast Addition on Some Properties and Phytic Acid Content of Tarhana Prepared with Different Cereal and Legume Products

DOI ↗

Flour

Change the flour, change the tarhana.

Research comparing tarhana made with wheat, whole-wheat and chickpea flour found that flour choice influenced nutritional, chemical and microbiological characteristics during fermentation.

Research contextThis does not establish that one flour makes tarhana universally healthier than another.

Kumral, 2015 — Nutritional, chemical and microbiological changes during fermentation of tarhana formulated with different flours. Chemistry Central Journal

Full text ↗

Fermentation & flavor

Time shapes tarhana's aroma.

Researchers tracking volatile aroma compounds during tarhana fermentation found that its aromatic profile changes as fermentation progresses.

This helps explain something traditional tarhana makers have long experienced through smell and taste: fermentation time changes the character of the food.

Research contextThis research concerns aroma development. It does not demonstrate that longer fermentation automatically creates greater health benefits.

Özdemir et al., 2019 — The effect of fermentation time on the volatile aromatic profile of tarhana dough. Food Science and Technology International

PubMed ↗

Microbial diversity

How tarhana is made matters.

Researchers comparing homemade and commercially produced tarhana found differences in the lactic-acid-bacteria communities present during fermentation.

The study is a reminder that “tarhana” is not one microbiologically identical product. Ingredients, environment and production methods can influence the fermentation ecosystem.

Research contextThis does not mean homemade tarhana is inherently better than commercially produced tarhana, or vice versa.

Şimşek, Özel & Çon, 2017 — Comparison of lactic acid bacteria diversity during the fermentation of Tarhana produced at home and on a commercial scale. Food Science and Biotechnology

Full text ↗

Food science

Fermentation changes the microbial environment.

Studies following tarhana during fermentation and drying show that its microbiological characteristics change throughout production.

Research has also found that microbiological and chemical characteristics can vary with raw materials, fermentation time and production technique.

Research contextFermentation should never be presented as a guarantee that a food is pathogen-free. Good food safety still depends on ingredients, process control, sanitation, storage and proper preparation.

Şengün & Karapınar, 2012 — Microbiological quality of Tarhana, Turkish cereal based fermented food. Quality Assurance and Safety of Crops & Foods

DOI ↗

Then we cook it

Fermented doesn't automatically mean probiotic.

Tarhana is fermented before it becomes soup.

But fermentation and probiotics are not the same thing.

Traditional tarhana soup is cooked before it is eaten. Heat can greatly reduce or eliminate microorganisms that were alive before cooking.

That is why we don't describe our soup as “probiotic.”

But that isn't the end of the scientific story.

Researchers are beginning to investigate fermentation-derived components from tarhana that do not depend on bacteria remaining alive.

A recent study isolated lactic acid bacteria from tarhana and investigated preparations including cell-free supernatants and heat-killed bacterial cell fragments in laboratory models.

The researchers specifically considered heat-killed fractions because tarhana is normally consumed after cooking.

Important distinctionThis was laboratory research on preparations derived from bacteria isolated from tarhana. It does not demonstrate that a bowl of cooked tarhana soup produces the same effects in the human body. We do not call our tarhana a postbiotic food.

Aydin, Bulut Albayrak & Boyacioğlu — Functional Properties of Lactic Acid Bacteria Postbiotics Isolated from Tarhana Samples. Probiotics and Antimicrobial Proteins (published online 2025 / journal issue 2026)

PubMed ↗

Evolving research

Researchers are changing tarhana to understand it.

Not every tarhana study investigates a traditional recipe.

Researchers also create experimental formulations using different flours, starter cultures, dairy products, legumes and specially developed grains.

These experiments can help scientists understand how individual ingredients and processes change the food.

High-amylose wheat

A 2024 study investigated tarhana made with specially selected high-amylose wheat and measured resistant starch and predicted glycemic characteristics using laboratory methods.

Köksel et al., 2024 — A Novel high-amylose wheat-based functional cereal soup (tarhana) with low glycemic index and high resistant starch. Journal of Cereal Science

DOI ↗

Does that mean tarhana is low-GI?

No.

The formulation used special high-amylose wheat and laboratory-based glycemic measurements. Those findings should not be generalized to all tarhana — including ours.

Human research

Human evidence is still limited.

Some experimental tarhana formulations have been investigated in human research.

However, these products may contain added probiotic cultures, prebiotics or other ingredients that are not part of traditional tarhana — and not necessarily part of our recipe.

Results from specially formulated products cannot automatically be applied to every bowl of tarhana.

Food chemistry is not the same as clinical evidence.
Laboratory activity is not the same as a demonstrated health effect in people.

Honest lines

What we know — and what we don't.

What research supports

  • Supported: Tarhana is a fermented food.
  • Supported: Lactic acid bacteria and yeasts participate in traditional tarhana fermentation.
  • Supported: Fermentation time can affect product characteristics.
  • Supported: Aroma develops and changes during fermentation.
  • Supported: Fermentation changes parts of the food's chemical composition.
  • Supported: Flour choice can influence the resulting tarhana.
  • Supported: Drying and cooking change the fermented product further.

What we don't claim

  • Not claimed: Tarhana cures or prevents disease.
  • Not claimed: Our cooked soup is a probiotic.
  • Not claimed: Twenty-one days is medically superior.
  • Not claimed: Tarhana “boosts immunity.”
  • Not claimed: Our soup has proven gut-health benefits in humans.
  • Not claimed: Every tarhana has a low glycemic index.
  • Not claimed: Our soup has proven postbiotic health benefits.

Research library

Research Library

  • Review

    Tarhana as a traditional Turkish fermented cereal food. Its recipe, production and composition.

    Dağlıoğlu O. (2000) — Nahrung

    DOI ↗

  • Food chemistry

    The effect of fermentation and storage on free amino acids of tarhana.

    Erbaş M, Ertuğay MF, Erbaş MO, Certel M. (2005) — International Journal of Food Sciences and Nutrition

    PubMed ↗

  • Food safety / Microbiology

    Microbiological quality of Tarhana, Turkish cereal based fermented food.

    Şengün IY, Karapınar M. (2012) — Quality Assurance and Safety of Crops & Foods

    DOI ↗

  • Food science / Microbiology

    Nutritional, chemical and microbiological changes during fermentation of tarhana formulated with different flours.

    Kumral A. (2015) — Chemistry Central Journal

    Full text ↗

  • Microbiology

    Comparison of lactic acid bacteria diversity during the fermentation of Tarhana produced at home and on a commercial scale.

    Şimşek Ö, Özel S, Çon AH. (2017) — Food Science and Biotechnology

    Full text ↗

  • Food chemistry

    Effects of Baker's Yeast Addition on Some Properties and Phytic Acid Content of Tarhana Prepared with Different Cereal and Legume Products.

    Ertaş N. (2018) — Journal of Food and Health Science

    DOI ↗

  • Fermentation / Sensory

    Microbiological Quality and Sensory Properties of Tarhanas Produced by Addition Saccharomyces cerevisiae and Sourdough as Starter Culture after Different Fermentation Periods.

    Coşkun F. (2019) — Asian Food Science Journal

    DOI ↗

  • Aroma / Fermentation

    The effect of fermentation time on the volatile aromatic profile of tarhana dough.

    Özdemir N, Şimşek Ö, Temiz H, Çon AH. (2019) — Food Science and Technology International

    PubMed ↗

  • Experimental formulation / In vitro

    A Novel high-amylose wheat-based functional cereal soup (tarhana) with low glycemic index and high resistant starch.

    Köksel H et al. (2024) — Journal of Cereal Science

    DOI ↗

  • In vitro / Postbiotic research

    Functional Properties of Lactic Acid Bacteria Postbiotics Isolated from Tarhana Samples.

    Aydin E, Bulut Albayrak Ç, Boyacioğlu O. (2025/2026) — Probiotics and Antimicrobial Proteins

    PubMed ↗

Tradition, understood differently

Generations first.
Science later.

Our family didn't need a laboratory to know that tarhana changes with time.

They watched the dough rise.
They mixed it.
They waited.
They smelled when it was changing.
And they passed the method forward.

Science gives us new ways to understand those changes.

It doesn't replace the tradition.
It helps us see what's happening inside it.

We don't need science to turn tarhana into a miracle food.

We use science to better understand the food we've been making for generations.

Discover our 21-day process