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There’s been some confusion on the definition of different terms so I would like to clarify a couple of points. Some people have been so focused on whether or not the lactic acid bacteria can survive in oxygen in this discussion that they’re missing the bigger point- lactic acid bacteria are only a portion of what is in a ferment and they’re only one piece of many in how ferments can affect your health. We need to look at the bigger picture.
I have said from the beginning of this series, I’m not writing a book in each post. Again, this is a blog, not a book. I’m putting things out piece by piece to help those who don’t have a science background absorb and digest the information instead of being frustrated and overwhelmed. So in an effort to not overwhelm, this series is moving slowly, but it is moving. There are many more posts to come, all broken down into bite-size pieces so it’s fun and informative instead of overwhelming. That means that the answers will not be tied up neatly in just a few, extremely long posts loaded with technical information. If that frustrates you, I suggest you check out one of any number of books on the subject instead.
Black and White
Whether or not something is a ferment is a black and white issue. Lactofermentation is ALWAYS done anaerobically in studies and in science. Fermentation is, by definition, completely anaerobic. You won’t find any studies done in anything but a completely airtight environment called fermentation.
Cellular respiration is always done in the presence of oxygen. Cellular respiration can be done with differing amounts of air being let into the chamber, but unless it’s completely oxygenless, it’s cellular respiration. Sometimes cellular respiration is called aerobic fermentation, but it’s a misnomer because it isn’t a true fermentation in any sense of the word. This confused term has come out of alcohol production because cellular respiration is used in some stages of the production of certain alcohols and people generally associate alcohol with fermentation.
So there is no such thing as a ‘partially anaerobic’ ferment or even a ferment in the presence of any oxygen. If any oxygen is present, it is cellular resipration and not fermentation. The oxygen present must first be used up before the bacteria switch to fermentation.
We already established in an earlier post that just being submerged under a brine doesn’t make for an anaerobic environment. The fermentation vessel must have an airtight seal to stop diffusion from putting oxygen into the brine.
Can probiotics live through cellular respiration?
Some can live in the presence of oxygen, yes. Some can not and we’ll be going over that soon- some of those are well-known gut healers. So the presence or absence of oxygen can determine the final bacterial profile. But that isn’t the only difference- competition also plays a role.
The Issue of Competition
The other issue to consider is competition. In a totally anaerobic ferment, oxygen-loving bacteria will not survive. They die off, giving the anaerobic bacteria more room to grow, more food and no competition. So the final bacterial counts and types are influenced greatly by the presence or absence of oxygen. Some of those oxygen-loving bacteria might not make you accurately sick, but they do have health effects. We’ll cover that soon.
Then How Come Aerobic Methods Get Tangy?
Some lactic acid bacteria can tolerate some amounts of oxygen. So, yes, they do produce lactic acid that drops the pH and give the lactic acid zip you associate with the fermented flavor. However, that lactic acid production doesn’t mean that only lactic acid bacteria are present. That is the real heart of this debate on lacto-fermentation. That’s the issue being lost here.
The Big Picture
The presence or absence of lactic acid bacteria is only one small piece of the puzzle. You also have to look at the effects of the aerobic bacteria, what an environment with or without oxygen causes the bacteria to produce, what products of fermentation (antioxidants, vitamins, enzymes) are killed off by oxygen or the lack of it and what the presence or absence of oxygen does to the final product (oxidation). All of these issues affect the final product and therefore they potentially effect your health when you consume them.
Please don’t miss the forest for the trees. Lactic acid bacteria are important, but they aren’t the whole picture. In the coming weeks I’ll be blogging more about the products of lactofermentation and cellular respiration and what happens to them when oxygen is present or absent and their potential and known effects.