How fermentation is taking over bars (and why some have gotten it wrong)

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Completing a recent tour of some of my favourite cities, talking all things technique and competition bartending, I found myself focusing much of my talk on fermentation. Fermentation has been influencing forward-thinking bars for some time, but only recently become more noticeable (especially through our social media feeds). 

But why has this become the ‘on-trend technique’ for so many bartenders, right now? Well, because it’s pretty bloody amazing. When done well, for the right reasons, fermentation gives us that sense of exploration as we devour new and unusual flavours. If you want to know how it gained such popularity, look no further than Sandor Ellix Katz’s The Art of Fermentation. The book is an in-depth exploration of the concept and processes around a technique that has been around longer than you or I.

To understand how this can be of assistance to your bar, you first need to understand what’s really going on when you ferment. Fermentation is the anaerobic process involving the application of natural bacteria feeding on the sugar and starch present in the food to produce lactic acid, or as Rene Redzepi puts it, “fermentation transform[s] more complicated foodstuffs into the raw material… rendering them more easily digestible, nutritious, and delicious.” This in turn preserves the food and extends shelf life. Or to put it in bar terms: the use of produce becomes more sustainable.

As with any new technique coming through the bar scene, there’s a period of trial and error which occurs whilst we all find our feet and realise the potential that the practice will have on our bar.

But more recently, another book has pushed fermentation into the limelight: The Noma Guide to Fermentation by Rene Redzepi and David Zilber. Ever since, our social media feeds have lit up with all things fermentable as bartenders experiment with lacto-fermented produce, kombucha, infused vinegars — the lot.

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At the base of all ferments should be some kind of wild fermentation. In this, you introduce diverse, naturally occurring bacteria that will, in turn, offer a variety of complex flavours, prior to introducing any external bacteria, yeast, or fungus. Through this method, you will also find a unique ‘funk’ that results from the wild lactic acid bacteria, that is natural to the environment (occuring either on the fruits and vegetables, on your hands, or floating in the air).

This process can be more efficiently controlled through the use of starter cultures or back-slopping (prepping microbial environments for fermentation… think the reuse of a SCOBY — the Symbiotic Culture Of Bacteria and Yeast — in kombucha or the same strain of yeast into a new batch of beer). By introducing a dose from a previous batch to your new liquid, you lower the PH of the solution and add acetic acid bacteria that will slow any undesirable microbes from acting on the liquid, ensuring the ones we want to act have a fighting chance.

Kurtis Bosley. Photo: Supplied

But as Evan Stroeve of Bulletin Place (who in my opinion has had some of the most experience on the matter) says, “you are working with living organisms that are unpredictable… nature reminds us that we don’t have power over her. We are as much patterned by her as the microbes, bacteria and yeast that we want to control.”

As fermentation will often add a funk to the product, liquid that has been invaded by unwanted pathogens turning it into something dangerous can sometimes go unnoticed and still be bottled and used. As many of us are still in the trial and error stage of testing this technique, drinks that use the fermented liquid but are clearly off are being served as the months invested into the final product are clouding the judgment of the bartender. Get others to taste the liquid and if there’s a hint of rotten, nose-stinging funk to it, throw it out.

Fermentation is an instinctive, intuitive process that will be best understood with trial and error. Understanding what your nose and palate is telling you, is key to knowing what’s happening with your fermentation. Don’t always trust a recipe as the environment you’re fermenting in will ultimately have the biggest influence on your final product.

Kurtis’ quick guide to success…

  • Do not eyeball measurements or take shortcuts, fermentation can become extremely dangerous if not done properly with use of the proper fermentation equipment (I think more than a few of us have had a bit of a scare when a bottle has exploded).
  • I can’t stress the importance of temperature in fermentation. Keep the temp between 25 and 32 degrees Celsius (room temperature) and keep it constant throughout the fermentation.
  • If you see some white on top of your ferment, scrape it off and reincorporate some oxygen into the liquid. If you see mold, throw it out and start again (yes, it’s difficult to do two months into a fermentation cycle).
  • Back-slopping is important to think about when continuing future ferments as your prepping the environment and giving your new ferment a helping hand towards success.
  • In order to prevent any unwanted pathogens from invading your ferment, causing it to taste off, cleanliness and sterilising your equipment needs to be prioritised.
  • When in doubt, throw it out.

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