What Is Hooch In Sourdough Starter?

What is hooch in sourdough starter?
Published on
21 November 2022
Gareth Busby
Gareth Busby

If you’ve noticed a liquid at the top of your starter and wondered what it is, it’s hooch! There are many misconceptions about hooch, whether it’s good, bad, or even if it matters at all if you find it! So let’s get to the truth about hooch – oh that rhymes!

How does hooch appear?

Enzymes and water in a sourdough starter break down starches in the flour into smaller sugars. The starter consumes these sugars and in doing so, it produces CO2, water and ethanol (alcohol) as well as other products. Like in bread, the CO2 gas gets trapped in the gluten structure and the starter rises. Eventually, the gluten in the starter weakens and the starter collapses on its own weight.

In the sourdough fermentation process, starches in the flour are broken down into sugars which undergo fermentation by the yeast and lactic acid bacteria which have cultivated the starter.

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Products of the available fermentation routes include carbon dioxide (gas), organic acids (acetic & lactic), acetate and ethanol (alcohol).

After feeding with flour a starter rises because the gas produced is captured by gluten in the flour forming a network, just like when bread is proofed.

If left to continue rising, the gluten weakens as acids and enzymes break down its protein structure, which combined with the prolonged stress of supporting the weight of the gas-filled structure leads to the starter collapsing.

Once a starter has peaked and then collapsed it becomes increasingly acidic, which is a common way to make a sourdough starter more sour. Yet as the starter sits unfed, it continues to ferment leading to it becoming acidic with more acetyl and ethanol produced.

Alcohol and acetyl are closely related as the heterofermentative pathway that some lactic bacteria follow, produces acetyl-p which can form acetate, carbon dioxide, acetic acid and/or alcohol.

Heterofermentation to produce acetic acid and ethanol
https://www.researchgate.net/figure/Hetero-fermentative-pathway-showing-the-production-of-lactic-acid-carbon-dioxide-and_fig4_278030425

As wet flour is heavier than alcohol the starter separates placing its acidic, alcoholic water at the top, and the moist flour at the bottom, with the upper layer of liquid, frequently called hooch.

Hooch is the liquid at the top

What is hooch?

Hooch is a combination of acetyl, acetate, ethanol, water, dead yeast cells and other waste. These elements are light so rise to the top of the starter when it has been unfed for a while and has become hungry for more flour.

Is hooch bad for a starter?

If hooch appears on your starter it’s been a while since it was last fed. If it’s clear or creamy coloured, it’s safe to use.

Where a starter has been unfed for many days, the enzymes necessary to process fresh flour may be lower in activity. This is due to the starter becoming more acidic which restricts non-acidic-loving enzymes.

Before using it to make bread, it’s wise to refresh it regularly for a few days to ensure it is rising properly. That said, many bakers don’t bother and use it straight away and suffer no ill effects. I suppose it depends on how long it has been left unfed.

If the hooch turns blue, red or black, it could be toxic so throw it out and begin making a starter from scratch.

How to get rid of hooch in sourdough starter?

Provided it’s not discoloured, you can pour the hooch away, are just stir it in. It’s up to you! Then discard the starter and feed it with fresh flour.

How to prevent hooch appearing in a sourdough starter?

A wetter starter is more likely to produce hooch than a thick one. Actually, I’ve never produced hooch when following my starter recipe, ever!

Here are two starter recipes, to compare:

Thin refreshment recipe

  • 50 grams water
  • 50 grams flour
  • 50 grams starter

Thick refreshment recipe

  • 40 grams water
  • 60 grams flour
  • 10 grams starter

In a thicker starter where the water-to-flour ratio is around 4:6:1, there is plenty of food for the yeast and bacteria to consume. This is even more true where rye or another wholegrain flour is used as they contain extra microorganisms to be consumed.

If using a 1:1:1 ratio of water, flour and starter, the starter will be more viscous. The extra water makes it easier for cells to pass, thus increasing the rate of fermentation activity in the starter.

It’s also worth considering that if the starter-to-flour ratio is equal in weight, compared with one that’s fed with 6 times the amount of flour to starter (as in my recipe), the fresh flour is going to be fully consumed much quicker than the one that’s fed with equal ratios of ingredients.

To sum up, a starter with more liquid and less flour is going to be faster at consuming the flour that it’s fed. This means it will collapse and produce hooch much sooner than the thicker starter.

The solution to preventing hooch from appearing in your starter is either:

  • Feed it more frequently
  • Reduce the water and increase the fresh flour when refreshing

Pouring off hooch vs stirring it in?

There’s no right or wrong when deciding if you want to include or remove the hooch. It contains mainly alcohol and acetol, alongside other waste products. Hooch is thought to be nature’s way of forming a barrier to protect the starter from outer elements and avoid infection. It’s not harmful so can be stirred in. 

The alcohol that’s contained will also add flavour, which can be nice but also overpowering!

As it’s liquid if you pour away the hooch the hydration of the starter will change. This means you’ll have to increase the water in your feeding recipe temporarily if you want it to have the same liquidity.

Frequently asked questions about hooch

My sourdough starter has hooch but not rising?
Hooch appearing on a starter is a sign that it is hungry. Without a fresh source of flour the starter cannot produce co2 gas so will not rise. For your starter to rise increase the flour used in your feeding recipe and discard on a regular basis.
What does hooch smell like on a sourdough starter?
Through a series of reactions, acetyl and alcohol produce ethyl acetate which is used as nail polish remover. The smell of hooch varies but is bound to include the very pungent smell of acetate, vinegar and/or alcohol
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