An Introduction to Fermentation
What is it? Why is it so important? How can you use it to make more delicious food?
Perhaps the question I get asked most often about my work at Shams El Balad’s food lab is “Why fermentation? What is the obsession with fermentation in the lab?”
While our lab is not singularly focused on fermentation, as others around the world are, it is still a central pillar of our work and one that drives several of our projects. It is also a particularly fascinating subject to our team, so perhaps “obsession” is not too far off.
Over the past few years, the term ’fermentation” has also become sort of a buzz-word for chefs, foodies and home-cooks alike, one that is extremely exciting to those who see its vast underutilized potential to cook better tasting, more sustainable, nutritious and innovative food.
There is a wealth of contemporary resources, both online and in print, about fermentation. I first became interested in the topic after reading Sandor Katz’s seminal book The Art of Fermentation, published in 2012. Most recently, there has been a resurgence of interest after Noma in Copenhagen published their book The Noma Guide to Fermentation, releasing a treasure trove of information and recipes from over ten years of work at their fermentation lab.
Whether you’re well versed in the art and science of fermentation or if the fundamental concept itself remains unclear, this guide will help bring you up to speed on the basic principles of fermentation. What is it? Why is it so important? How can you use it to make more delicious food?
If you mix pretty much any fruit or vegetable with salt, (sometimes also water and/or sugar), and leave it out on the counter for a few days or weeks something happens, raw ingredients transform.
Sometimes, this process produces complex tastes and aromas that were not found in the fresh ingredients to begin with. Imagine the difference in taste between a fermented cucumber and a fresh one, or a pressed olive and a raw one (if you’ve ever tried one, not tasty at all).
You may not know it yet, but many of the foods we often eat are fermented. Bread, cheese, chocolate, coffee, beer and wine are only a few of the fermented foods that form the foundations of our diet. It is believed that fermentation, particularly that of bread and beer, is what actually convinced our ancestors to forego the hunter-gatherer lifestyle for a more cultivated one. Fermentation has been central to human life ever since.
The word “fermentation” describes the process by which this transformation occurs, the Noma Guide defines this perhaps most clearly as,
“the transformation of food by microorganisms—whether bacteria, yeasts, or mold. To be slightly more specific, it is the transformation of food through enzymes produced by those microorganisms. And finally, in the strictest scientific definition, fermentation is the process by which a microorganism converts sugar into another substance in the absence of oxygen.”
This broad definition accounts for many different types of ferments that vary by the type of microorganisms at work breaking down sugars and the substances produced as a result.
One of the most common types of ferments, and the one we work on most, is lactic acid fermentation, where wild yeasts work in unison with lactic acid bacteria (or LAB) to feed off the sugars in fruits and vegetables. These LAB exist ubiquitously in the air and on every organic surface including the skin of humans, fruits and vegetables.
LAB convert the sugars into lactic acid and carbon dioxide. Lactic acid is what gives the unique vinegary, acidic aroma to fermented foods. Carbon dioxide is what makes fermented foods and beverages, like beer or pickles, fizzy. In doing so, these microorganisms reproduce and, in any closed fermentation environment, this process will follow a curve as they eventually exhaust the sugars in the fermented food. That’s why you want to catch your pickles and olives at the right moment before they turn into mush.
Most strains of fermentative yeast and bacteria require no oxygen to reproduce except in certain special conditions such as saccharomyces cerevisiae for bread making and acetic acid bacteria (AAB), the culprit for turning your leftover alcohol into vinegar when exposed to oxygen.
To many of us today, this process may seem like rotting. Indeed, given the wrong set of circumstances fermentation will lead to food turning inedible and “rotting”. That is why, through thousands of years of trial and error, we use salt among other ingredients to create the correct environment for the right types of yeasts and bacteria to thrive. While salt is critical to fermentation, it does not account for the transformation itself rather it inhibits the growth of bad bacteria that would otherwise outnumber and dominate the desired LAB.
To me, fermentation is the closest thing to magic in the real world.
There are countless strains of wild yeasts and bacteria at work in fermentation all around the world. From the farm - the soil, water and air, to the different people handling them, fruits and vegetables collect a diversity of these yeasts and bacteria that proliferate under the right fermentation conditions to preserve the food.
In fact, we have come to learn that the unique diversity of these microorganisms is deeply linked with their geographic context. The qualities of a wild ferment prepared in Amman may vary considerably if prepared elsewhere. San Francisco Sourdough is famous for the particular taste that results from naturally occurring yeasts and bacteria in the bay area. This exact taste would be impossible to replicate elsewhere, just as it would be to recreate the taste of our sourdough bread anywhere but Amman.
The same applies to any ferment, from the cheeses we source from Jerash and Madaba to the local wines produced near Mafraq. The term most commonly used to describe this phenomenon is “terroir”. Perhaps most deeply associated with winemaking and viticulture, terroir refers to the specificity of the taste of a ferment due to its geographic context, and specifically the diversity of microorganisms that exist within that context.
Terroir is the reason why fermenting a cucumber from the North of Jordan and one from the South in the same place, with the same salt and water will result in different aromas and textures.
It is also one of the reasons why all cheeses have unique characteristics, while they are all made of the same three ingredients, milk, rennet and salt, and why so many famous cheeses we know today are associated with particular towns or regions. Parmesan from Reginna for instance ferments with a blend of three microorganisms that produce its unique aroma and taste. They don’t exist together in the same ratios anywhere else to produce the right flavor.
At Shams we have two soda starters - one started in the lab and the other in the barista room - the latter is more aggressive and ferments faster with a distinct bitterness at the end that the former doesn’t have.
Scaling down even further, it is also the unique diversity of microorganisms within each and every ferment that lends each its unique tastes and aromas. It may be from the ingredient itself, its source and exposure along the supply chain or even the diversity of microorganisms that exist on the hands of whoever is preparing the ferment. In Korean, the word “son-mat” literally translates to hand taste and describes this poetic, natural variation.
I like to think of fermentation as expressing an ingredient’s life story.
Fermentation used to be a ubiquitous process in every household across every culture in the world. As the global food chain rapidly industrialized over the past several decades, we have moved away from wild fermentation in our homes. While it may seem intimidating at first to start experimenting with producing your own ferments, it is best to start simple. Observe, test and taste as you go to gain a tighter grip on the process.
The most common and simple ferment is probably the cucumber pickle, here is a basic method for preparing fermented cucumbers from scratch using nothing but salt and water. We always recommend fermenting vegetables on their own to start, before layering in aromatics (like garlic, chili or other spices) in order to better understand the impact of each.
Enough baby cucumbers to fill jar of your choice (make sure to sterilize the jar before use)
4.5% brine (which is 45g of salt to every one liter of water - roughly 2.5 tablespoons per liter)
Optional aromatics: garlic, chili pepper, dill, grape leaf, coriander seeds
Place in sterilized jar (with optional aromatics if using)
Fill with brine
Weigh down cucumbers so that they remain fully immersed in the brine (there are many ways to do this, with a small bowl or plastic bag full of water).This step is important as anything above the surface of the brine will invite oxygen hungry mold.
Now wait. Once your jar goes cloudy, it’s a good sign - wait until the cloudiness clears up and your cucumbers are fermented and ready to eat. The warmer the weather, the faster the fermentation will go.