Fearless Fermentation: The Role of Oxygen
Welcome to the Fearless Fermentation series where I will be addressing some common topics, questions & concerns regarding fermentation !
In this post we’re going to talk about the role of oxygen in fermentation
Fearless Fermentation: The Role of Oxygen
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The three main components of the fermentation process are salt, sugar & oxygen. We covered salt in the last post which you can find HERE & we’ll be going over sugar in the next one.
Let’s talk about the role of oxygen because it is just as important as the ingredients you’ll be reaching for.
Oxygenation & Bacteria
Did you know that some bacteria require oxygen to survive while other strains thrive in low to no oxygen environments?
To simply things, as we don’t need a science degree to practice the ancient method of food preservation we call fermentation, but we do need to talk about bacteria & respiration. This falls into 2 different classifications aerobic & anaerobic respiration
Aerobic Bacteria
This classification of bacteria require oxygen for growth & they are known to thrive in oxygen rich environments.
This process allows the bacteria to oxidize the organic molecules generating energy in the form of Adenosine triphosphate AKA ATP. In other words this means bacteria uses the oxygen to burn as fuel to produce energy.
This type of bacteria require open air fermentation, allowing the oxygen to be fully present. Recipes that call for things like paper towel lids would fall into this category.
A good example of the aerobic process is found in sourdough.
Key Characteristics of the Aerobic Process
Rapid microbial growth, because oxygen is available these microorganisms can produce energy more efficiently
Complete substrate utilization allowing the microorganisms to fully oxidize sugars present which results in carbon dioxide
Temperature & pH control requirement, because aerobic fermentation generates more heat due to increased metabolic activity.
Anaerobic Bacteria
This classification of bacteria do not require oxygen for growth & can thrive in low or no-oxygen conditions. Some anaerobic bacteria can even be killed by the presence of oxygen.
This process uses nitrate, sulfate or carbon dioxide instead of oxygen
This type of bacteria require a closed vessel with an air lock that can keep oxygen out. Airlock lids are not mandatory but they do make things easier.
If you do not have an airlock lid simply use a 2 part mason jar lid & place it on the jar somewhat loosely to allow air to escape. You may need to burp the jar which means you unscrew the lid slightly to allow the air to escape. I will suggest doing this over the sink as sometimes some of the liquid escapes creating a bit of a mess, ask me how I know.
A good example of the anaerobic process is found in sauerkraut.
Key Characteristics of the Anaerobic Process
Slower but specialized production, because the microorganisms have to work harder to extract energy they typically result in slower growth
Unique metabolic pathways by activating alternative biochemical pathways such as alcohol fermentation by yeast & lactic acid fermentation by bacteria
Extended fermentation times, some of these fermentation require weeks, months or even years to complete. Think aged cheese, wine & sauerkraut
Fearless Fermentation: The Role of Oxygen
We do have a few different types of anaerobic bacteria who each have a different relationship with oxygen.
Aerotolerant anaerobes → bacteria that don’t require oxygen for growth but can tolerate its presence. Streptococcus is an example
Facultative anaerobes → bacteria that can grow with or without oxygen. It can switch back & forth between utilizing oxygen when it’s available & not requiring it at all when it isn’t. Escherichia coli E.coli is an example
Microaerophiles → bacteria that require oxygen for growth but at lower concentrations, 2-10% oxygen. Anything higher can be toxic. Campylobacter jejuni, the bacteria that commonly causes food poisoning is an example
Obligate anaerobes → bacteria that are killed by exposure to oxygen. Clostridium botulinum, the bacteria that causes botulism is an example
I hope you now have a bit of an understanding about how different bacteria uses oxygen in different ways.
So next time you come across a fermentation recipe you’ll have an idea about the oxygen requirements which will help you create some really delicious, powerfully gut healing probiotic ferments.
Comment down below with any of your fermentation questions
Until next time, may you find Peace wherever you are!
Sources
https://iere.org/what-is-the-difference-between-anaerobic-and-aerobic-bacteria/
https://fermentaholics.com/anaerobic-vs-aerobic-in-fermentation/