Fermented Mixed Berries

This past weekend, I splurged and bought a few packs of berries (a special treat indeed, considering the snow still falls in the mountains) because I was so inspired by a new recipe: fermented berries.  We tend to rely on our fermented vegetables like sour pickles and hot pink jalapeno garlic kraut, as well as tonics like beet kvass, Cinnamon Spice Kombucha, and Jun tea.  Just when I thought I had fermented nearly everything under the sun, I came across the idea of fermented berries.

It seemed almost sacrilege at first, to take a beautiful sweet-tart and ripe berry, lovely in its own right, and to ferment it.  Would I ruin them?  Would my son make a face if he tried them?  No, we loved them.

What You Need to Know about Fermenting Berries

Fermentation is a near magical process, one that transforms food.  My kitchen is filled with little (and big) jars filled with fruits, vegetables and grains in varying stage of fermentation: bubbling sourdough starter, sparkling honey-sweet Jun tea, robust homemade sauerkraut, yogurt and sour cream.

Despite all my crocks and bubbling brews, I had never thought to ferment berries until I stumbled across a recipe for them in Oh Lardy’s Guide to Fermenting Fruits and Vegetables that is a simple, little digital guide to fermentation.  (And, FYI, it’s available for immediate download for about $7 with the coupon code FERMENT30.)

The recipe seemed simple enough: berries, a sweetener, water and a starter culture to help kickstart the fermentation process.  In the end, they form a delightfully tart and faintly effervescent treat.

Why You Should Use Fermentation Weights

As with other ferments, you’ll want to take care that the berries remain fully submerged in liquid, lest they mold.  While big crocks come with huge weights, you probably don’t plan to ferment gallons of berries at a time (oh the expense!), and instead, like me, you’ll use a pint-sized glass jar with a tight-fitting lid.  Having a few fermentation weights (like these) handy can help to make sure that the berries remain submerged, and are, therefore, less prone to contamination by stray microbes. In the end, they form a delightfully tart and faintly effervescent treat.  Other options include a sterilized stone, or a lid that happens to fit inside your jar, wedging down the berries.

Using a Starter Culture for Your Fermented Berries

Most of the fermentation projects I undertake in my kitchen are wild ferments; that is, they rely only on the wild bacteria and microorganisms that surround us all the time.  That is how I make my homemade sauerkrauts, my fermented lemons, my pickled green tomatoes.

Yet, for some ferments, a starter culture can be particularly helpful.  When I expect to ferment something for a short period of time, like fruit chutneys, berries, or condiments, I almost always use a starter culture to kickstart the process.  I typically use a commercial starter culture (available here), but you can also use fresh whey drawn off from yogurt, a bit of brine from other fermented vegetables, kombucha or water kefir.  I tend to avoid kombucha and water kefir as starter cultures as, in my experience, they can produce a slimy texture from time to time.

Fermenting with Honey

Whenever I mention honey as an additive during fermentation, a slew of emails and comments inevitably follow, and they all ask (or say) the same thing, “Honey is antimicrobial, so won’t it prevent or hinder fermentation?”  The answer is a swift and simple, “No.”

Yes, honey is antimicrobial because it has a low water content.  When that water content increases, perhaps because you’ve mixed honey with water or whey, then honey ferments just fine.  That’s how we get traditional honey wines like Mead and Ethiopian T’ej.   The addition of a sweetener in this recipe for fermented berries helps, like the starter, culture to speed up fermentation by providing a source of carbohydrates for the beneficial bacteria you’re hoping to cultivate.  The sugars that remain after fermentation give the berries a wonderful sweetness to balance their tartness.

How to Know When Your Berries Are Ready

Unlike cabbage and root vegetables which typically benefit for a very long period of fermentation, berries benefit from a very short fermentation, only one to two days.  This keeps their inherent sweetness a little bit better intact, and helps you to catch them before they turn alcoholic.  After about a day, you’ll notice little bubbles appearing at the surface of the jar. Open the jar, spoon out a berry and taste it.  Does it taste tart and faintly effervescent?  Good.  Your berries are done.  Now, place the lid over your jar, tuck it in the fridge, and use the berries within a month.

How to Use Your Fermented Berries

Raspberries and blackberries soften during fermentation, transforming into a thin and slightly jammy texture while blueberries puff a bit.  You can puree them together in a blender, until smooth, using them as a berry sauce over homemade honey custard, yogurt or ice cream, like we do, or drop them whole into your blender for your morning smoothie.  I plan to stir some of the puree into a bottle full of Jun tea to make a berry soda that I think will be positively lovely.