Here's the thing: it's surprisingly easy to make your own soda! And seriously, can you think of a better project for summer? (I can't!). Here's everything you need to know.
Brewing your own soda means producing carbonation inside the bottle, as a natural byproduct of fermentation. You combine the ingredients in the right proportions, let them do their thing for a few days, and voila - you've got a fizzy, refreshing drink to enjoy at the end. That you made yourself! (Seriously cool.)
What You'll Need
This project involves a few specific pieces of equipment. Not super expensive - the whole thing may run you around $40 or less. But if you're new to home brewing, you'll definitely need to make a trip to a homebrew store or order online. My beer-brewing friend Sam recommends Northern Brewer as a reliable online source for everything you need at reasonable prices.
Here are the specific things you're going to need:
1-Gallon Glass Jug
The first phase of fermentation happens in a jug like this. The 1-gallon size will fill 6-8 bottles, which is probably the right amount for most families. (If you'd like to make a smaller batch, you can choose a half-gallon jug instead.)
Drilled Stopper (Size: 6.5)
"Drilled" means it has a hole drilled through it vertically, which is what your airlock will fit into. They come in various sizes, and the 6.5 size fit my 1-gallon jug perfectly.
Double-Chamber "Bubbler" Airlock
This plastic piece plugs into the drilled hole in the stopper. During fermentation, it's partially filled with water, so that you can see gas bubbles emerge from the fermenting soda. (Keep reading for details.)
(If you are already familiar with home brewing and prefer a 3-piece airlock, you can use that instead. I used the 2-chamber airlock in my recipes and photography, so that's what I'm recommending for people who are new to this process.)
16-Ounce Flip-Top Bottles and Tops
These bottles MUST be sourced from a reliable brewing supply store. You may find less expensive flip-top bottles at a crafting store, but DON'T use these - they are for decorative use only! This is really important, because the right bottles are designed to withstand the actual, significant pressure of soda fermentation. If you use a decorative bottle, the pressure could cause it to explode, hurling glass shards through your home. If you shy away from purchasing the right bottles, then this is not the project for you.
Depending on your source, the bottles may come with the flip-tops already attached, or the tops may be sold separately (they were separate for me). If they're separate, they're fairly easy to put on yourself. (Just be sure to put them on the right direction.)
At my local homebrew store, I had the option of purchasing individual bottles or a case of 12. (I went for the case, because we're going to make soda in my summer camp this year!). If you plan to make more than one flavor at a time, you'll want to get the case. But if you prefer to make just one batch, buying the bottles individually will save you a little money.
(If you are a home brewer you may be comfortable bottling with crown caps, but the pressure in soda fermentation is greater than that in beer, so these aren't sufficient for this. It needs to be a flip-top.)
In our soda-making recipes, yeast is the microbe we can thank for all those bubbles! The yeast consumes the sugar in the soda and converts it to carbon dioxide (and technically, a teensy-weensy bit of alcohol, but not enough to worry anyone - keep reading for more on this).
For the best bubbles, you'll want to use champagne yeast. Using baker's yeast or brewer's yeast will produce a less-bubbly brew. You'll just need one small packet - it costs about $1, and gives you more than you need.
Good, Non-Chlorinated Water
The chlorine in tap water can kill the yeast and prevent it from making the bubbles you want. This may or may not be a problem for you, depending on the tap water in your particular area. But to play it safe, purchase a gallon of good bottled water (I used Poland Spring for this, but any good-quality bottled water would be fine).
4 Steps to Brewing Naturally Carbonated Soda
Once you have everything you need, you're ready to get started! You'll want to wash all your equipment in hot, soapy water and make sure your hands are clean, so you don't introduce any dangerous bacteria to the mix during the process. But you don't need to sterilize anything. Home-brewed soda will ferment in the bottle, then be stored in the refrigerator, so you don't need to prepare it to be shelf-stable (as you would in a canning process).
I've created recipes for Hibiscus-Lime Soda, Lemon-Lime Soda and Parsley Soda (!), but whatever flavor you're making, you'll follow these 4 steps:
Step 1: Make Flavored Syrup
This is the sweet flavor base for your soda. You'll make a simple syrup from equal parts sugar and water, and infuse it with flavor by steeping fruit or herbs along with the sugar-water mixture.
(By the way, if you've ever worked in a restaurant you know that commercial fountain sodas start the same way. The restaurant buys pouches of the sweet syrup base from, say, the Coca-Cola Company. These pouches are attached to the fountain machine, which mixes it with carbonated water when you press the lever to pour your soda. If you want to make your own soda this way, you can mix your flavored syrup with carbonated water and skip the remaining steps!)
Step 2: Big-Batch Fermentation
You'll combine the flavored syrup with bottled water in your glass jug (along with a few pieces of the fruit you used if desired). Add the yeast, put the stopper in the top, put just a little water in the airlock chamber and plug the airlock into the hole. Set this jug with the airlock attached in a dark place (UV light can kill yeast) for 12-48 hours to let the yeast feast on the sugars and begin fermentation.
What's a dark place? Home brewers often have a special cabinet they use to keep their brews away from light during fermentation. If you don't have some sort of cabinet that your gallon-jug can fit into with it's airlock in place, you can wrap it up in a black towel or blanket to block the light.
The time needed for this step will depend on the weather. Yeast prefer to work in warm weather, so on a warm day it will take less time. On a cold day, you may need the entire 48 hours.
How do you know when it's ready? Watch the airlock - when you see 2 bubbles pass through within a minute, it's ready to be bottled.
Step 3: Final Fermentation in Bottles
When it's ready, you'll transfer it to your flip-top bottles to finish brewing in the bottles. Use a strainer set over a funnel to catch the remaining small bits of citrus pulp or other clumps of matter. Don't fill the bottles all the way to the top - you need to allow about 1.5-2 inches of space in the neck of the bottle for for additional gasses to accumulate at the top.
When your bottles are full and the caps are tightly sealed, put them back in your dark place to finish fermenting. Again, the time needed will vary depending on the temperature, from 24-48 hours. At this point, the only way to know if it's fully fermented is to open a bottle and test it.
When you pop the top of a bottle, it should "pop" audibly a bit when you open it, telling you that pressure has begun to build up. When you taste it, it should have a noticeable effervescence.
Note: It won't taste as good as it will the following day and thereafter, for several reasons! For one thing, soda tastes much better cold (obvs!). For another, it will continue to ferment (albeit more slowly) under refrigeration. And the bubbles will fizz much more dramatically when it's cold than at room temperature. (For more on what to expect from your finished soda, read through the What to Expect section below.)
Step 4: Refrigerate
Once your soda is ready, it goes in the refrigerator for 24 hours. After that, you'll continue to store your soda in the fridge until you're ready to drink it. You don't go through a canning-style sterilization process when bottling soda (because that would have killed the yeast!), and the cold and dark refrigerator will slow fermentation to a crawl to keep your soda just right.
After the first 24 hours, you can store your soda in the fridge for up to 4 weeks (although it's probably best to drink within 2 weeks; you may notice the taste begin to change from continued fermentation after that).
How to Open the Bottles
Just in case there is more pressure in your bottles than you expect, you may want to lay a towel over the top of the bottle as you open it. It's not likely, but occasionally the soda may gush out of the bottle when you open it, like Champagne!
To open hold the bottle with the round neck piece of the wire baling facing away from you. Use your thumbs to press on the back of the vertical wire baling. This will pop the round piece forward and release the top.
What to expect
Will it taste like commercial soda?
In a word, no. Brewing your own naturally carbonated soda is a fun project to make a fizzy and delicious drink - but it doesn't imitate commercial soda. Your homemade Lemon-Lime Soda won't taste like Sprite. It will be refreshing and delicious, but it will be different.
In my experience, the bubbles in homemade soda are softer than the sharp carbonation you get from canned commercial sodas. And the outcome of your home-brewed soda will probably vary a bit from batch to batch, because fermentation is a wild, natural process. You're making a hand-crafted drink, so by definition, it won't be factory standard. Like anything handmade, that's part of the charm.
So bottom line, if you want to drink Coke or Sprite, then you're better off drinking Coke or Sprite! But if you want a fun project that makes a refreshing, fizzy and delicious drink, make your own soda.
How Sweet Will It Be?
The sweet syrup you make in Step 1 will be very sweet. If you taste at each step in the process, you'll notice the sweetness diminish as time goes on. This is because the yeast are consuming the sugars and converting them into the by-products that make bubbles in your soda. The longer you store the soda, the less sweet it will taste. In my experience, the sweetness is best within the first week of brewing, but you may have a different preference.
Won't this make alcohol?
Yes and no. The scientific fact is that alcohol, along with carbon-dioxide (bubbles), is one of the byproducts of any yeast fermentation. That's what yeasts make. But saying there is alcohol in soda feels a bit like insisting that a tomato is a fruit. Technically true, but irrelevant in practice. So yes, alcohol is a chemical compound found in any yeast-fermented food.
But no, homemade soda is not an alcoholic beverage. Your homemade soda will contain less than 1% alcohol, compared to beer (also yeast-fermented), which contains 4%-6% alcohol. The difference is that soda is refrigerated quickly to limit the action of the yeast. Once it's carbonated, it's refrigerated. I don't taste or notice any alcohol in my finished soda, and neither do my kids.
I've created recipes for three soda flavors: Lemon-Lime, Hibiscus Lime, and Parsley. (Fans of A Series of Unfortunate Events may recognize Parsley Soda from the books. Turns out it's a real thing!)
You can vary the ingredients to make your own flavored syrups, and experiment with other herbs and fruit. Or follow these recipes to make the same kind I've made. Have fun!