Take a walk on the wild side
Uncertainty is an inevitable fact about fermentation, and for better or for worse, every batch is a surprise. Factors such as temperature, vegetable sugar content, and the surrounding environment of your kitchen can all affect the end product. Sometimes it’s so good you want to start a business (sounds too familiar) and many times you just want to toss it and forget about it. In this article we’re diving into the factors that make our ferment unique: temperature, sugar, and seasonality.
Just like how you’d make kimchi at home, we rely on the ‘wild fermentation’ process. Wild fermentation means to let the fermentation start on its own without a starter culture. Cultured starter has its place when fermenting something that is more susceptible to the growth of undesirable bacteria, such as bread or kombucha. Having a strong culture to start decreases the failure rate, which is crucial when we need fast and predictable production. Luckily kimchi and lacto-fermented vegetables don’t need starter culture as the process is quite forgiving. The salinity and the acidity from Lactic Acid Bacteria (LAB) create a hostile environment for pathogens such as salmonella.
The food that feeds the bacteria culture plays an important role in creating an edible ferment. In the case of kimchi, it is the sugar and starch in the vegetables. The sugar found in the vegetables is our first wild card, as it is far from being consistent. The level of sugar is due to many factors such as climate, growing season, and maturity of the vegetables. An old carrot might taste spicier and earthier than a young carrot packed with natural sugar. When making kimchi, we base our formulation on the total weight of the produce instead of the sugar and other nutrient content (Imagine having a recipe that asks exactly that… shudder). This variant creates a unique flavour profile everytime we ferment. The starch content also affects the fermentation time. As you may guess, more sugar means more active bacteria and thus a faster fermentation. Theoretically, using an older and spicier carrot will result in a longer fermentation compared to a young carrot. We don’t have a sophisticated tool to check when our kimchi is ripening, however, we can guesstimate by measuring the pH value every day until it reaches the desired acidity (this can take from 5 to 10 days).
Fermentation Temperature and Time
Seasonality impacts temperature and temperature affects time.
We may regard temperature as a catalyst for fermentation. Bacteria, just like us, have an ideal temperature to survive. The warmer the weather (to a certain degree), the more active the bacteria, and the faster the fermentation. We know from our previous post that LAB is responsible for fermentation. Keep in mind that LAB is an order of fermenting bacteria, not a species (remember your grade 10 biology acronyms?). Therefore, some LAB prefer warmer weather, and some like it a little cooler. Our job is to pick which one makes tastier kimchi. For example, L. mesenteroides is active at 30 Celsius and produces a tiny amount of ethanol – giving the kimchi a slight boozy flavour. Whereas, Leuconostoc lactis creates acetic acid, giving it a sharp vinegary taste. All of these strains of bacteria compete for space and food to reproduce. With the relationship between temperature and fermentation, we can hypothesize that summer kimchi will ferment fast and will have a strong flavour (I once fermented kimchi in Thailand and It only took 3 days). Fast fermentation is also a sign of one dominating bacteria culture, and often gives one flat sour note. Whether this is desirable, it is a matter of taste. If you like sour and robust kimchi, summer kimchi is for you.
Traditional Korean Method of Preserving
Winter Kimchi Underground
Primetime to make kimchi?
At the same time, when the temperature is low in the winter, the air is sterilized, and bacterial activity is lower. This can be beneficial for us because things don’t turn into a big acid soup so fast. Lower activity means more time and opportunity for different strands of LAB to shine. This is why winter kimchi often has more nuance and complexity in its flavour. The right fermentation pace is offset by the less-exciting winter produce. It’s a great balance that nature offers us.
On the other hand, when the temperature drops too low (around under 4c), LAB takes too long to colonize and acidify the food. The less acidic environment allows mold or yeast to grow. This is why you often find mouldy ferments at the back of the fridge (forsaken and forgotten). Fortunately this is an easy prevention, simply leave a new ferment out at room temperature for a couple days to maximize the chance of LAB to thrive, then move your ferment to the fridge to slow down fermentation.
Can we make a new tradition?
From temperature, to sugar, to seasonality, each batch of kimchi is unique. We feel that this characteristic deserves some recognition. From this day forward, we are creating a new tradition of doing a kimchi review of every new batch that we make. Wine folks have it, same goes for coffee and tea. We’re sure there’s a spot for kimchi super tasters. Help us think of the word to call them 🙂 (connoisseurs? aficionado? epicurean? cognoscenti?).
This review is a little late at the time this blog is written, we have less than 30 jars of Fall 2020 kimchi left. We’re hoping to do this as a seasonal tradition going forward.