From kimchi to kombucha, it’s easy to ferment at home. Here’s all the kit you need

TThe theory is simple: fruits and vegetables (and grains and milk, but fermenting them is more complex) contain natural bacteria that, when deprived of air, can inhibit the growth of microbes that would otherwise spoil them. They do this by converting the carbohydrates and sugars in the food into an acid in which pathogens and other microbes have a hard time thriving.

This is what gives fermented foods and drinks their signature flavour, as well as the famous probiotic qualities that fuel their popularity. Still, they’re not cheap to buy; at Ocado, for example, a 250g jar of kimchi costs £5.

Home fermentation, however, is fun, easy, and has minimal start-up costs. Most of the “ingredients” are already on hand, as long as you have a knife, fresh fruit or veggies, a jar, sugar, and/or salt. Here’s all the kit you need to get started—and the stuff you shouldn’t waste your money on.

Salty

“Your salt needs to be high-quality and preservative-free,” says Mark Diacono, author of Ferment From Scratch. “Otherwise, the preservatives will work against the bacteria you want to grow.” Try Maldon salt (£2.70, tesco.com) or Himalayan pink salt (£1.99, aldi.co.uk), but any other high-quality, preservative-free rock or sea salt will do.

Pots

The jars you are going to ferment your fruit or vegetables in should ideally be strong enough to withstand the pressure that is created when carbon dioxide is released. You can use glass jars if you want to ferment on a small scale or if you are just starting out.

“I like to do old Bold Bean Co jars to quickly do smaller fermentations, as they are large and sturdy. If you are on a tight budget or are experimenting, use recycled jars,” says Ukrainian chef and food writer Olia Herculeswho regularly teaches fermentation classes. Remember to unscrew the jars regularly to let the gases escape, otherwise you will have a mess on your hands.

Kilner jars (£4.50, ocado.com) are more pressure-resistant, come in a variety of sizes and often have lids. If you feel like you have enough going on in your life without having to burp kimchi, you can even buy a valve to screw onto the Kilner, “so you don’t have to worry about burping at all”.

Weights

The most important thing about fermenting food is to keep air out of it. This means using a jar with an airtight seal, but also making sure that whatever you’re fermenting is always submerged in the brine. You can use any homemade weight for this, as long as it’s sterile—Dacono uses freezer bags filled with water—but for peace of mind, he recommends:pickle pebbles(£9.99, happykombucha.co.uk): “glass discs that fit perfectly into the jar and push down the sauerkraut or pickled cucumber you’ve made”.

The need to keep the vegetables submerged and to occasionally refill the brine is why Jefferson stays away from crockpots. “You have to keep checking the water seal and you can’t really see what’s going on – less of a concern if it’s all glass.”

Muslin and sieve

Fermented drinks are different though; kombucha, tepache and the like need air to ferment. For this you will need (in addition to your jar) some muslin (£3.50, happykombucha.co.uk ), a sieve (£9.99, lakeland.co.uk ) and a couple of glass bottles that can withstand high pressure; Diacono sources these from Kilner or similar flip-top glass bottles (£3.82, nisbets.co.uk ). The muslin sits over the jar while the fruit (or tea, in the case of kombucha) ferments, before being strained into the bottle, ready to serve.

Things you don’t need

There are some things you think you need that you don’t really need—at least not when you’re just starting out. A mandolin is one of them. Food writer and author of Your daily vegetablesJoe Woodhouse, says he likes his Bron Coucke stainless steel mandoline because it’s lasted 20 years, and “you can get everything in the same shape, so it ferments at the same speed — and it feels chef-y,” he says — but neither he nor anyone else finds them necessary. A sharp knife will do; fermentation enthusiast and co-founder of online farmers market, Wylde MarketNick Jefferson recommends Robert Welch for affordable quality.

Sterilizing equipment and supplies aren’t just unnecessary; they’re counterproductive. The kit you use should be clean, but not sterile. All you need is a dishwasher or hot, soapy water, says Hercules. A fermentation recipe book can be helpful to have on hand in the early days—and even his own book, suggests Diacono James Read’s Of Cabbages and Kimchi —but there are plenty of online guides. Try Doug McMaster’s Zero Waste Cooking School, BBC Good Food or the Zoe’s Beginner’s Guide to Fermentation. Jefferson learned a lot from It’s alive with Brad.

And last but not least, you will need a refrigerator to store and preserve your ferments when they are ready to eat.