A guide to making kombucha at home — get your SCOBY and get to steeping

Now that you've mastered (or given up on) homemade sourdough bread, perhaps it's time to consider brewing kombucha at home. The popular, fermented tea beverage, available bottled at many grocery stores, is surprisingly easy to make yourself. 

The process requires little hands-on work — the fermentation itself does most of the heavy lifting — and according to the experts we talked to, it's hard to go wrong if you follow the directions and source a symbiotic culture of bacteria and yeast (SCOBY), or "mother," to kick off the process. For advice on getting a batch started right, we reached out to two experienced brewers: Ian Young, a food safety expert at Ryerson University, and Brew Your Bucha director Derek Saito. Here, their safety guidelines, brewing techniques and troubleshooting tips for making great kombucha at home. 

The basics of the brew

There are essentially two phases for making this naturally-carbonated beverage, although you can skip the second step if you prefer flat kombucha. "The first fermentation is where you're essentially making sweet tea and [adding] the SCOBY ... once the tea has cooled down to [room] temperature," says Saito. The culture breaks down the sugar and the tea, a process which can take about a week depending on the temperature of the room. 

The second fermentation happens to the kombucha in the bottle, along with any flavouring such as fruit, juices, herbs and spices. "In that second fermentation, you just let the kombucha sit at room temperature for three or four days and, in that process, the kombucha will self-carbonate," says Saito. "Pop it in the fridge for another two days, and it will be nice and [ready to drink]."

As a fermented beverage, kombucha has many purported health benefits although "there's not a lot of solid evidence as to a lot of the claims that are made," says Young. Still, you may consider limiting the amount of kombucha you drink. The BC Centre for Disease Control, for example, recommends no more than a half cup per day. Studies have linked drinking too much kombucha to acidosis and liver damage, and there have been cases of food poisoning from home brews. 

Check with your doctor before drinking kombucha if you have existing health conditions or have a weakened immune system. Additionally, kombucha contains trace amounts of alcohol, which can be an issue for pregnant women and young children. To minimize the alcohol content of your homemade kombucha, Young recommends refrigerating the brew as soon as it's ready and consuming it within a week or two. 

A last safety note: as with any fermentation process, keeping hands, containers and equipment clean is imperative for making a product that is safe to consume. You don't need to sterilize everything the same way that you might for canning, but clean with "regular sanitation" methods (e.g. with soap and water or in the dishwasher) between each use, advises Young

A guide to making kombucha at home

Start by sourcing a SCOBY and some starter liquid

You can definitely grow your own SCOBY from scratch using an unpasteurized, unflavoured kombucha, but to save time (the process could take at least a month or two, says Young) and to ensure an easy start, consider getting one that's ready to go from a friend or a specialty retailer. 

If you're getting a SCOBY from someone you know, you should inspect it for signs of mould. "That would be a sign that it's contaminated," says Young. "It should also come in some kombucha liquid. SCOBYs have to be kept in a low-pH environment to prevent the formation of unwanted microbes. Mould would be the most common concern, but also any other bacteria that could get in there." Commercially-sold SCOBYs are professionally preserved and packaged, and contamination shouldn't be a concern. 

The starter liquid, essentially raw kombucha that's well fermented and very vinegary, is also key to the brew, explains Saito. "If you just threw a SCOBY [into a jar of sweet tea], there's a good chance that if the tea doesn't ferment quickly enough, the brew could develop mould," says Saito. If that happens, you'll need to dispose of the SCOBY and start over. 

Pick a tea type

According to Saito, you can use almost any type of tea to brew kombucha: black, green, white and oolong are all good options. He recommends avoiding ones that are very aromatic or contain essential oils. 

If you want to switch to a new tea type, you might want to do it in stages so it's not too sudden an adjustment for the SCOBY. "In between switching from black tea to green tea, you might want to do one brew where it's half black and half green tea," says Saito. "Then for the next brew you could use all green tea." And while any tea can be used, Saito encourages experimentation with different blends to discover your preferences. "A lot of people just use whatever is available … [but] I do notice that if you use higher quality tea, you will taste a slight difference in the kombucha." 

Time to steep and ferment

Young recommends minimizing the amount of time your tea sits at room temperature. "As soon as the tea is done brewing, you should put the SCOBY in," he says. "You don't want to leave that warm, brewed, [sweetened] tea sitting overnight or for a couple of days, [as] that's when you can introduce moulds or other problems." 

You will also want to monitor the acidity of the brew using pH strips, which are available online. "Ideally, you would check after seven to 10 days; make sure the pH is 4.2 [or below]," says Young. "If it's not, that means that there's something wrong. Maybe the SCOBY is not effective … or you're doing it at too low of a temperature." 

Room temperature is best for fermenting your kombucha. Some experts have found that 25 C is optimal. Saito thinks 22 C is ideal, and notes a warmer temperature than that will speed up the fermentation, while anything less will slow it down.

Do a taste test 

After a week, check in on the taste of your brew. Saito recommends using a straw to extract and taste a bit of the kombucha or you can also use a pH strip to measure the acidity. "It's more of a preference on flavour than anything," he says. "Some people prefer their kombucha to be almost like vinegar; others like it to have a bit more sugar. You want to move on to the second fermentation when it's maybe a day or two from your optimal sweetness level." The kombucha will continue to get a little more acidic in the second fermentation stage. "You do want to leave a bit of sugar in there, because that's how you get your carbonation — the SCOBY is essentially consuming the sugar and the byproduct is [carbon dioxide]," explains Saito. He recommends you follow brewing instructions as written for your first batch and save adjustments and experimentation for later brews. 

Save that SCOBY for next time

With each brew, your cultures will expand and multiply. "As you continue to brew, you're going to accumulate [additional] SCOBYs, and you're not going to want to put all of them in your brew each time," says Saito. "If you do that, then the SCOBY gets a little bit stronger and stronger each time, and it'll throw off the fermentation periods that you're used to."

So what to do with the excess? Saito recommends giving them away to friends, composting them, eating them ("they have the texture of coconut jelly"), or making dog treats with dried cultures.

To store a SCOBY while taking a break from fermenting or going on vacation, Saito recommends placing it in a SCOBY hotel. Simply put it into a cloth-covered jar with a cup or two of the remaining raw kombucha and place the jar in a cool, dark place. You can even put the jar in your fridge to put the SCOBY into "hibernation mode" — but be warned you may not be able to wake it up.

Ferment, flavour and enjoy! 

"Never add flavouring to the container where you keep the SCOBY and do the [first] fermentation," says Young. You can add fruit, herbs, juices and spices to your serving bottles to flavour your raw kombucha.  

Many recipes are available online with precise quantities and instructions (including one at the Brew Your Bucha website), and you can look to favourite store-bought kombuchas for inspiration. For something easy and inexpensive, Saito recommends making ginger kombucha. "I like to add a little bit of honey for sweetening and carbonation, and then you can purée ginger and squeeze the juice into the second fermentation bottles," says Saito. 

Truc Nguyen is a Toronto-based writer, editor and stylist. Follow her at @trucnguyen.