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3 Fermentation Techniques for The Best DIY Sodas!

Three bottles of fermented grapefruit soda, besides the ingredients used to make the fermentation starters

Hi, Friends of Cocktails and Fermentation! There are so many great reasons to dive into the rich world of fermentation that it would be impossible to pack it all into one post, but we’ll still cover a lot including what it is, why you should know and care about it, and most importantly, how to use it to make some amazing cocktails!


We again partnered with Mijenta Tequila, and quite fittingly so, because the rich fermentation of their special yeast is key in highlighting Mijenta’s natural flavors. Plus, fermentation’s sustainable approach lines up with their Echo Verde mantra. So today we’ll test out fermentation techniques by making 3 different fermented grapefruit sodas, and what goes better with that than a Paloma?

That’s right, three Palomas. They’ll be different due to three different fermentation starters - Pineapple Tepache, Lactofermented Grapefruit and a Ginger Bug - but the best part is that it will be an easy process with minimum gear needed, you’ll only need to keep your eye on it. Now let’s get moving, so first thing’s first, what is fermentation? 

Fermentation is a natural process where microorganisms like yeast, bacteria, or fungi convert sugars and carbohydrates into alcohol, acids, or gasses. Some evidence shows that people were making an alcoholic beverage from fermented rice, grapes, and honey in China as far back as 7.000 BC, so why has this practice remained for so long? Since we’re doing everything in three’s today, I’ll give you 3 reasons why.

First, preservation and sustainability. Fermentation has been historically used as a method of preservation, extending the shelf life of fruits, vegetables, and other ingredients. That not only means less waste, but it’s also useful when creating homemade syrups, shrubs, or infusions for your drinks. You can also freeze any starter and use it down the line again, which we’ll do with our tepache for a future episode.

Second, fermentation is a flavor enhancer. It brings complex, almost funky flavors and aromas to your ingredients, elevating the taste profile of your cocktails. Third, health benefits. Fermented ingredients can contain probiotics that are good for your gut health, digestion and overall well-being - when consumed in moderation, of course.

Now for today’s fermentation starters, which will bring the yeast or bacteria we add to the mixture we want to ferment, we’re starting with Lactofermented Grapefruit. We’ve done something similar in the past with oranges using a ziplock bag, but we’re trying a more traditional method this time. Let’s begin, it’s Fermentation Time!

A Paloma cocktail made with homemade fermented grapefruit soda, using tepache as a starter

Lactofermented Grapefruit Starter

● 450g Grapefruit Peels and Pulp

● 9g Non-iodized Salt

● 15mL · 0.5oz Simple Syrup

● 2 drops 20% Saline Solution


Begin by rinsing, drying and peeling some grapefruits, then place the peels and the pulp on a scale because we’re adding 2% of the weight in salt. Keep in mind not to use anything antibacterial when rinsing the grapefruits, and as always when using citrus peels, make sure they are organic or have food-grade peels to make sure your final soda is safe to consume!

Don’t worry if you get a different amount of grapefruit, to adjust the amount of salt you can use the Mijenta calculators here before moving on. So place everything into a non-reactive jar and give everything a good mix for the salt to distribute, then slightly mash everything up - keep in mind we want to remove the air bubbles and submerge all the peels.

Let this sit for about 7 days, opening the jar every 2-3 days to release the CO2 produced by the bacteria. The salt will kill bad bacteria, giving the good bacteria a chance to convert the sugar in the grapefruit into lactic acid, hence lacto-fermentation. Lactic acid is a natural preservative that holds back the growth of harmful bacteria, and once the grapefruit is fermented you’ll see bubbles forming and all the contents will float on top.

Don’t forget to open the jar to avoid the CO2 building up, which can cause it to explode.  After it has fermented, we can strain out the solids using a cloth filter, and a handy tool to squeeze out all of the liquid is a potato ricer. Now we have our fermentation starter, but don’t throw away the solids either, we’ll use them in a future episode, so dehydrate them in a dehydrator or an oven.

With the lacto-fermented grapefruit ready, let’s move on to tepache. This fermented Mexican drink is a wonderful way to use up pineapple leftovers from either juicing or eating this delicious fruit. We juiced the flesh, the fronds go in the freezer for garnishes, and we’ll use up all of the peels, the core and the pulp. Just make sure to rinse your pineapple first to get rid of any unwanted residues. 

Tepache Starter

● Leftover Pineapple Skins, Core and Pulp

● 1250g Water

● 100g Sugar

Place everything in a big jar and stir with a wooden spoon. Then cover with a cloth filter to prevent anything from joining the party in the jar, and use a rubber band to hold it in place. The natural yeasts that live on the pineapple skins will jump-start the fermentation process, and after 7 days you should see plenty of bubbles, so let’s repeat the steps from before. Strain, squeeze, and we have our tepache starter ready. 

Don’t throw away the pineapple solids either, because we’ll use them in the future to make pineapple liqueur, so freeze it meanwhile and let’s move onto fermentation starter number 3: Ginger Bug!

Ginger Bug Starter

● 210g Unpeeled Ginger

● 300g Water

● 100g Sugar

● 240g Rich 2:1 Syrup 

Begin by placing 30g of unpeeled ginger and 100g of sugar into 300g of water. Now do the same as with pineapple, stir with a wooden spoon to mix everything nicely, then cover with a cloth filter and a rubber band. This will take about a week as well, but it will take a bit more of your participation. The wild bacteria and native yeasts on the ginger will start to grow rapidly and eat the sugar, so every day you need to add a little fuel to the fire of fermentation. 

So take the filter off, and add 30g of sliced ginger and, instead of sugar, 40g of rich, 2:1 syrup. This mixes in faster and starts working with the yeast straight away. Stir those in, cover back up and repeat the next few days, until you get a liquid with plenty of bubbles, which is the CO2 being produced by the microorganisms. If nothing is happening after 1 week, that usually means the ginger’s surface was treated and there wasn't enough yeast on it. That’s why I always look for organic ginger. 

So to finish this one well, strain out the ginger and the liquid part is your ginger bug. Don't discard the ginger either, since we’ll use it in a future episode as well. Next step will be making the sodas, which have to come with a warning: we’ll be dealing with second fermentation, which produces a lot of CO2 and makes your drink nice and bubbly. Great, right? Yes, but it can also be very dangerous, as our director Robi found out when making fizzy kombucha. 

A glass bottle can easily, and extremely loudly blow up, if you forget to release the gasses and it’s not built to withstand that much pressure. That's actually why we’ll actually be re-using old soda plastic bottles, they were built to withstand pressure. Plus, we’ll be able to squeeze out excess air when we start. All of these recipes will be for 500mL or 16oz bottles, so with that in mind, let’s make some grapefruit sodas! 

Lactofermented Grapefruit Soda

● 285mL ·  9.5oz Water

● 75mL · 2.5oz Simple Syrup

● 45mL · 1.5oz Lactofermented Grapefruit Starter

● 22.5mL · 0.75oz Red Orange Juice

So add the ingredients into an empty soda bottle, then squeeze out as much air as possible and when the liquid is nearly at the pot close the cap and that’s it. Now we wait for the magic to happen. The time can depend on our starters and the temperature of the room, but it should be done within 12 hours. 

Once the CO2 builds up the pressure the bottle will expand back to its classic shape. Once you see the bottle is fully expanded it’s time to carefully open the bottle, release the pressure and then squeeze out the air again to give the soda room to carbonate for a second time. Then place this in the bottle for the soda to chill and carbonate once again. It will happen fast, but the carbonization will stop once the soda chills down. 

We’re now ready to move onto our next sodas. 

Tepache Grapefruit Soda

● 140mL ·  4.66oz Water

● 160mL · 5.33oz Grapefruit Juice

● 90mL · 3oz Tepache Starter

● 75g Boiling Water

● 150g Sugar 

● 1.5g Dried Hibiscus

We’ll begin by making hibiscus tea, so combine the boiling water with the sugar and the dried hibiscus flowers. Stir and leave to cool before filtering, then mix the remaining ingredients and we’ll repeat the same steps as for our last soda. Let’s now make our Ginger Grapefruit Soda before testing them out in a Paloma. 

Ginger Grapefruit Soda

● 75mL ·  2.5oz Simple Syrup

● 140mL ·  4.66oz Water

● 160mL · 5.33oz Grapefruit Juice

● 45mL · 1.5oz Ginger Bug Starter

● Beetroot Juice

Combine the water, simple syrup, grapefruit juice and Ginger Bug starter, then for the red color we’ll add a few drops of beetroot juice. Then we wait again for the fermentation magic to happen, and with that we have our 3 unique, fermented grapefruit sodas. If that doesn’t get you ready for a Paloma then nothing will, and we’ll make all three of them with Mijenta Blanco. 

This award-winning, additive free, sustainable tequila is aromatic, elegant and complex, with subtle notes of cantaloupe, honey and cinnamon. It’s bright, with a nice minerally and pleasantly grassy finish. Perfect for a paloma or three. 

The Paloma

● 45mL ·  1.5oz Mijenta Blanco Tequila

● 15mL ·  0.5oz Lime Super Juice

● 90mL · 3oz Fermented Grapefruit Soda

● 4 drops 20% Saline Solution*

The preparation is the same for all three. Into a chilled highball glass filled with ice add the tequila, lime Super Juice and saline solution if you’re using the Ginger or Tepache Grapefruit Soda, because the Lactofermented one will have salinity already. Then top up with our fermented soda, give all cocktails a few turns and a lift with a barspoon to mix the ingredients, then we add the garnishes. 

A grapefruit wedge, a pineapple frond, and a slice of ginger, respectivelym, and after all your patient work, it’s time to give them a try. The color is a beautiful pink everywhere, so they definitely pass the eye test for a Paloma. All the versions have their unique flavor, with different starters adding their kick, and the fermentation providing the funkiness. Mijenta elevates the cocktails even higher with its minerality, perfectly matching all three sodas.

And which one’s my favorite one? It’s a close call, but it’s the Grapefruit. Something about the lactofermentation pairs exceptionally well with tequila blanco, and with that you’ve made it to The Bottom of The Glass. Today I have a book recommendation for everyone that would like to dive deeper into fermentation and maybe try out what other starters can spice up your cocktail game.


It’s my fermentation bible, by Sandor Ellix Katz, titled “The Art of Fermentation”. I’ll see you next time, with some ways to use some of the leftovers from today and prep for a large crowd. Cheers, Friends of Cocktails!


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