The Temperature Switch: Baking for GABA

In the world of sourdough, the fridge is king. We are taught that the "cold retard" is the secret to everything: better crust, better flavour, and better scheduling. We assume that colder is always better.

But if you are baking for mental health—specifically for anxiety relief—the fridge might be working against you.

The key molecule here is GABA (gamma-aminobutyric acid). It is the brain's primary inhibitory neurotransmitter, the biological "off switch" for stress and anxiety. And to maximise it in your bread, you may need to turn up the heat.

The GABA Mechanism

GABA is produced by Lactic Acid Bacteria (LAB) through the decarboxylation of glutamate, an amino acid abundant in wheat protein [1]. The enzyme responsible for this conversion is glutamate decarboxylase (GAD).

Like all enzymes, GAD has a "sweet spot"—a specific temperature range where it operates at peak efficiency. When you put your dough in the fridge at 4°C, you are slowing down all enzymatic activity. While this preserves the dough structure, it puts the GABA factories on ice.

The Heat Spike: Why 30°C–35°C Matters

Research into specific sourdough strains, such as Levilactobacillus brevis and Lactiplantibacillus plantarum, reveals a crucial finding: GABA production is temperature-dependent.

Studies indicate that the optimal temperature for GABA accumulation is often significantly higher than standard room temperature, typically ranging between 30°C and 37°C (86°F–99°F) [2, 3]. At these temperatures, the bacteria are metabolically hyper-active, converting glutamate into GABA at a rate that far outpaces what occurs at cooler temperatures.

One study found that L. brevis produced the highest concentration of GABA at 30°C–35°C, with production dropping off sharply at lower temperatures [4]. Another study on L. plantarum confirmed that maintaining a fermentation temperature of 35°C significantly enhanced GABA yield compared to 25°C [5].

But Does It Reach the Brain?

A common question is whether eating GABA actually impacts anxiety, given that the molecule struggles to cross the blood-brain barrier. The answer lies in the Gut-Brain Axis.

While dietary GABA may not flood the brain directly, it can bind to GABA receptors in the Enteric Nervous System (the "second brain" in your gut). This activation sends calming signals to the brain via the vagus nerve [6]. So, while the bread doesn't drug you, it may signal your body to stand down.

The Protocol: The "Warm Bulk" Strategy

To bake for GABA, we need to rethink the fermentation schedule. Instead of a long, cold slumber, we need a period of intense, warm activity.

This doesn't mean abandoning the fridge entirely (we still want the flavour complexity and dough handling benefits of a cold proof). It means inserting a Temperature Switch during the bulk fermentation.

The Hybrid Protocol:

1. The Warm Spike (The GABA Phase): Conduct the bulk fermentation (the first rise) in a warm environment, ideally between 30°C and 32°C. This can be achieved using a proofing box, a switched-off oven with the light on, or a warm spot in the kitchen. Maintain this for 3–4 hours. This is when the GABA accumulation peaks.

2. The Cold Retard (The Flavour/Structure Phase): Once the dough has risen significantly (30–50%), shape it and move it to the fridge for a cold retard (8–12 hours). This halts the rapid fermentation, preventing over-proofing, and allows for flavour development and gluten tightening.

By front-loading the heat, you allow the bacteria to perform their specific enzymatic task (GABA synthesis) before locking the structure in place with cold.

Conclusion

Sourdough is a responsive technology. If you want sourness, you manipulate hydration. If you want an open crumb, you manipulate handling. And if you want GABA—that precious, calming neurotransmitter—you must manipulate temperature.

Don't be afraid of the heat. Your starter thrives in it, and your brain might just thank you for it.

References

1. Verni, M., Vekka, A., Immonen, M., Katina, K., Rizzello, C. G., & Coda, R. (2022). Biosynthesis of γ‐aminobutyric acid by lactic acid bacteria in surplus bread and its use in bread making. Journal of Applied Microbiology.

2. Li, H., Qiu, T., Huang, G., & Cao, Y. (2010). Production of gamma-aminobutyric acid by Lactobacillus brevisNCL912 using fed-batch fermentation. Microbial Cell Factories.

3. Dhakal, R., Bajpai, V. K., & Baek, K. H. (2012). Production of gaba (γ - Aminobutyric acid) by microorganisms: a review. Brazilian Journal of Microbiology.

4. Villegas, J. M., Brown, L., de Giori, G. S., & Hebert, E. M. (2016). Optimization of batch culture conditions for GABA production by Lactobacillus brevis CRL 1942, isolated from quinoa sourdough. LWT - Food Science and Technology.

5. Shan, Y., Man, C. X., Han, X., Li, L., Guo, Y., Deng, Y., ... & Jiang, Y. (2015). Evaluation of improved γ-aminobutyric acid production in yogurt using Lactobacillus plantarum NDC 75017. Journal of Dairy Science.

6. Cryan, J. F., & Dinan, T. G. (2012). Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience, 13(10), 701-712.

Last updated: 11 December, 2025