A Quick Guide to Bad Smells in Fermentation
My ferment doesn’t smell right: how to tell if your fermentation has gone bad by its smell
Fermentation is a delicate balance of microorganisms working together to create complex flavors and aromas. However, when things go wrong, harmful bacteria can take over, producing distinct and unpleasant smells. Learning to recognize these odors is essential for ensuring safety in your fermentation projects.
Here's a simple guide to the most common warning signs and what they might mean.
Sour or Rotten
Example: The sharp, acrid smell of spoiled milk or yogurt that's gone bad in the fridge.
Comparison: It may also resemble the scent of wet socks left in a closed bag for too long or old, mushy vegetables like potatoes or lettuce starting to rot.
Cause: Likely contamination by Bacillus spp. or other lactic acid-producing bacteria that have turned harmful in the wrong conditions.
Foul or Putrid
Example: The overwhelming stench of garbage left out too long or decaying meat.
Comparison: It can also smell like sewage or a blocked drain, with an offensive sulfuric, "rotten egg" odor.
Cause: Typically caused by Clostridium spp., which produce hydrogen sulfide and other foul-smelling compounds during spoilage.
Ammonia-like
Example: The sharp, irritating smell of cat urine or a cleaning product with ammonia.
Comparison: It can also be similar to the smell that comes from overripe fish or seafood that’s starting to decay.
Cause: This smell results from the breakdown of proteins into ammonia and other nitrogenous compounds by certain bacteria or microorganisms.
General Tip:
If any of these smells are detected in food or fermentation projects, they are red flags indicating spoilage or contamination. Always prioritize safety and discard items with these odors.
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Denis Pashkov
cosmos society