Why You'll Love This Recipe

There are plenty of fermented apple recipes available, but this version is particularly beginner-friendly while still offering plenty of depth of flavour.

Naturally fermented

This recipe relies entirely on natural lacto-fermentation rather than vinegar, allowing the apples to develop their own fresh, tangy flavour over several days.

Perfect for beginners

If you're just getting started with fermentation for beginners, apples are wonderfully forgiving. The process is straightforward, and you'll quickly learn the basics of creating a successful ferment.

Sweet meets savoury

The combination of crisp seasonal apples, garlic, and mustard seeds creates an unexpected balance of sweetness, acidity, and savoury complexity that pairs beautifully with many meals.

Sustainable food preservation

Fermentation is one of the easiest ways to reduce food waste. Instead of letting surplus apples spoil, you can naturally preserve them for weeks while creating something entirely new.

Plastic-free storage

Preparing the recipe in reusable glass jars supports a more sustainable kitchen. Glass won't absorb flavours or odours and can be reused for years, making it an excellent choice for regular fermentation.

Great for meal prep

Once fermented, these apples become a versatile ingredient you can enjoy throughout the week. Add them to salads, sandwiches, cheese boards, grain bowls, or serve them alongside roasted meats and vegetables.

Minimal ingredients

With only apples, garlic, mustard seeds, salt, and water, you probably already have everything you need to start fermenting today.

Ingredients

This recipe makes one 700 ml jar.

Ingredients

• 400–500 g firm apples – Choose crisp varieties such as Pink Lady, Braeburn, Gala, Elstar, or Jazz. Firmer apples stay pleasantly crunchy throughout fermentation.
• 2 garlic cloves, sliced – Adds savoury depth and complements the sweetness of the apples.
• 1–2 teaspoons mustard seeds – Introduces subtle spice, texture, and aromatic flavour.
• 500 ml filtered water – Filtered water is preferable because chlorine may slow fermentation.
• 10 g sea salt – Creates a 2% brine that encourages beneficial bacteria while discouraging unwanted microbes.

Optional additions

• 1 small sprig fresh thyme
• 1 small sprig rosemary
• A few black peppercorns
• A small piece of fresh chilli

These ingredients can be added individually or combined to create different flavour profiles while keeping the fermentation process exactly the same.

 Why Each Ingredient Matters

Apples

Firm, fresh apples contain natural sugars that feed beneficial bacteria during fermentation. Choosing seasonal apples usually provides the best flavour and texture.

Garlic

Garlic develops a milder, sweeter flavour during fermentation while adding subtle savoury notes throughout the jar.

Mustard Seeds

Mustard seeds slowly release their flavour into the brine, creating gentle warmth without overpowering the fruit.

Sea Salt

Salt is essential in every fermentation recipe. It suppresses unwanted bacteria while creating ideal conditions for lactic acid bacteria to flourish.

Water

Filtered water helps produce a healthy fermentation because excessive chlorine can inhibit bacterial activity.

Equipment Needed

Although fermenting apples doesn't require expensive equipment, using the right tools makes the process considerably easier—especially if you're new to fermentation.

For this recipe, we used the Pearl Jars Fermentation Set for Beginners, which includes everything needed to maintain ideal fermentation conditions while helping prevent common beginner mistakes.

Wide-Mouth Glass Fermentation Jar

A reusable glass fermentation jar is one of the most important pieces of equipment.

Glass is:

• Non-reactive
• Easy to clean
• Durable
• Plastic-free
• Ideal for acidic foods

The wide opening also makes it much easier to pack apple slices neatly into the jar and remove them once fermentation is complete.

Glass Fermentation Weight

One of the biggest challenges during apple fermentation is preventing fruit from floating above the brine.

A glass fermentation weight keeps every apple slice completely submerged, reducing exposure to oxygen and helping prevent spoilage. Keeping ingredients below the surface is one of the simplest ways to encourage a successful ferment.

Airlock Lid

As fermentation begins, beneficial bacteria produce carbon dioxide. This gas needs somewhere to escape.

An airlock lid allows carbon dioxide to leave the jar while minimising oxygen entering from outside. This creates ideal conditions for natural fermentation and significantly reduces the need to "burp" jars manually.

Many beginners find that using an airlock makes fermentation much more predictable and less intimidating.

Measuring Spoon or Kitchen Scale

Accurate salt measurements are surprisingly important.

Too little salt may allow unwanted bacteria to grow.

Too much salt can slow fermentation considerably.

For consistent results, measuring 10 g sea salt for every 500 ml water creates a reliable 2% brine suitable for most fruit and vegetable fermentations.

Step-by-Step Instructions

Making Fermented Apples with Mustard & Garlic is surprisingly simple. Once everything is prepared, nature does most of the work. The beneficial bacteria naturally present on the apples begin transforming the sugars into lactic acid, creating their distinctive tangy flavour while preserving the fruit.

Step 1 – Prepare the Apples

Wash the apples thoroughly under cold running water. Since the peel contains naturally occurring beneficial bacteria that help kick-start fermentation, there's no need to peel them.

Cut each apple into wedges or thick slices and remove the core. Try to keep the slices roughly the same thickness so they ferment evenly while staying pleasantly crisp.

Firm apple varieties such as Pink Lady, Braeburn, Gala, Jazz or Elstar work particularly well because they retain their texture throughout fermentation.

Step 2 – Pack the Jar

Place the sliced apples into a clean 700 ml glass fermentation jar.

As you fill the jar, add:

• 2 sliced garlic cloves
• 1–2 teaspoons mustard seeds

If using optional flavourings, add them now as well:

• Fresh thyme
• Rosemary
• Black peppercorns
• Fresh chilli

Pack everything firmly but avoid compressing the apples too tightly. Leaving small spaces allows the brine to circulate freely around the fruit.

Step 3 – Prepare the 2% Brine

In a separate container, dissolve:

• 10 g sea salt
• 500 ml filtered water

Stir until the salt has completely dissolved.

Using the correct salt concentration is one of the easiest ways to encourage successful natural fermentation. A 2% brine provides ideal conditions for beneficial lactic acid bacteria while helping suppress unwanted microorganisms.

Filtered water is recommended because chlorine found in some tap water may slow the fermentation process.

Step 4 – Pour in the Brine

Slowly pour the brine into the jar until every apple slice is completely covered.

Leave approximately 2–3 cm of headspace at the top of the jar. During fermentation, carbon dioxide is produced, so this extra space prevents the brine from overflowing.

Step 5 – Add the Fermentation Weight

Place the glass fermentation weight gently on top of the apples.

This is one of the most important steps.

Fruit naturally wants to float, but successful lacto-fermentation requires every piece to remain fully submerged beneath the brine. Exposure to oxygen increases the risk of mould developing on the surface.

The fermentation weight keeps everything safely below the liquid throughout the entire fermentation process.

Step 6 – Attach the Airlock Lid

Secure the lid and fit the airlock.

As fermentation begins, naturally occurring bacteria produce carbon dioxide. The airlock allows this gas to escape while preventing excess oxygen from entering the jar.

For beginners, this greatly simplifies fermentation because there's no need to regularly loosen the lid to release pressure.

Step 7 – Ferment at Room Temperature

Place the jar somewhere out of direct sunlight at approximately 18–22°C.

Fermentation usually becomes active within 24–48 hours.

You may notice:

• Tiny bubbles rising through the brine
• Slight cloudiness
• A pleasantly tangy aroma
• Gentle fizz when opening the jar

These are all normal signs that fermentation is progressing well.

Taste your apples after 2 days and continue fermenting until they reach your preferred balance of sweetness and acidity.

How Lacto-Fermentation Works

Many people are surprised by how little effort fermentation actually requires. Once the ingredients are submerged in a properly balanced salt brine, naturally occurring microorganisms take over.

The process behind lacto-fermentation has been used safely for thousands of years to preserve vegetables, fruits, and other foods without refrigeration.

Beneficial Bacteria Do the Work

Fresh apples naturally carry microscopic bacteria on their skin. Among these are lactic acid bacteria, which thrive in salty, oxygen-limited environments.

Once submerged beneath the brine, these beneficial bacteria begin consuming the apples' natural sugars.

As they feed, they produce lactic acid.

This gradual increase in acidity:

• Preserves the apples naturally
• Creates their tangy flavour
• Helps prevent the growth of unwanted microorganisms
• Extends shelf life without artificial preservatives

Unlike vinegar pickling, the acidity develops naturally during fermentation, creating a much deeper and more complex flavour.

Why Salt Is So Important

Salt plays several essential roles during fermentation.

It:

• Draws moisture from the fruit
• Slows undesirable bacteria
• Encourages lactic acid bacteria
• Helps maintain a crisp texture

Using too little salt can increase the risk of spoilage, while excessive salt may slow fermentation significantly.

That's why measuring your brine accurately is so important.

Why Everything Must Stay Under the Brine

Successful apple fermentation happens in an anaerobic environment, meaning there is very little oxygen.

Any fruit floating above the surface has access to air, increasing the likelihood of mould or spoilage.

A fermentation weight keeps every slice safely submerged while allowing beneficial bacteria to flourish beneath the surface.

Carbon Dioxide Is a Good Sign

During fermentation, bacteria naturally produce carbon dioxide.

This is why you'll often notice:

• bubbles
• fizzing
• slight pressure inside the jar

Using an airlock lid allows these gases to escape automatically without exposing the ferment to unnecessary oxygen.

Ideal Fermentation Temperature

For this recipe, room temperatures between 18°C and 22°C produce the most consistent results.

Warmer rooms speed up fermentation.

Cooler temperatures slow it down.

Avoid placing the jar:

• in direct sunlight
• near radiators
• beside ovens
• on very cold windowsills

A stable temperature encourages a healthy, predictable ferment.

Why Use a Fermentation Kit?

Technically, apples can be fermented using almost any clean glass jar. However, beginners often encounter the same challenges:

• Apples float above the brine.
• Surface mould develops.
• Pressure builds inside the jar.
• Salt measurements are inconsistent.
• Fermentation becomes difficult to manage.

For this recipe, we used the Pearl Jars Fermentation Set for Beginners because each component helps solve one of these common issues naturally.

The wide-mouth glass jar makes it easy to pack apple slices neatly and clean the jar thoroughly afterwards.

The glass fermentation weight keeps every slice submerged beneath the brine, reducing exposure to oxygen and helping create ideal fermentation conditions.

The airlock lid automatically releases carbon dioxide while limiting oxygen exposure, making fermentation more reliable and requiring less day-to-day attention.

Finally, measuring the correct amount of salt ensures the beneficial bacteria have the best possible environment to thrive.

Together, these simple tools make fermentation for beginners more approachable while also helping experienced home fermenters achieve consistent results time after time.

How Long Should Apples Ferment?

One of the best things about this fermented apple recipe is that you can customise the flavour simply by adjusting the fermentation time.

After 3 Days

The apples remain very crisp with only a light tang.

Perfect if you prefer a fresher, fruitier flavour.

After 5 Days

The sweetness softens noticeably, while the garlic and mustard become more pronounced.

For many people, this is the ideal balance between sweet, savoury, and tangy.

After 7 Days

The apples develop a deeper fermented flavour with more acidity and complexity.

They remain pleasantly crunchy but taste distinctly more savoury than fresh apples.

The exact timing depends on room temperature and personal preference, so don't be afraid to taste the apples every day after the second day until they reach your favourite flavour.

Storage Tips

Once your Fermented Apples with Mustard & Garlic have reached your preferred flavour, it's time to slow the fermentation process.

Simply transfer the jar to the refrigerator. The colder temperature doesn't stop fermentation completely, but it slows it significantly, allowing the apples to maintain their flavour and crisp texture for much longer.

For the best quality:

• Store the jar in the refrigerator.
• Always keep the apples fully submerged beneath the brine.
• Use clean utensils each time you remove apples from the jar.
• Reseal the lid after every use.

When stored correctly, the apples are best enjoyed within 2–3 weeks.

Although they remain safe for longer if properly refrigerated, the texture gradually softens over time. Most people prefer them while they still retain their fresh crunch.

Common Fermentation Mistakes

Even experienced fermenters occasionally encounter small issues. Fortunately, most are easy to prevent and even easier to solve.

The Apples Are Floating

Floating fruit is probably the most common beginner problem.

Anything exposed to air has a greater chance of developing mould.

Solution: Always use a glass fermentation weight to keep every apple slice completely beneath the brine.

Too Much Salt

Excess salt slows bacterial activity.

Your apples may take much longer to ferment and can taste overly salty.

Solution: Carefully measure your ingredients and prepare a consistent 2% brine.

Too Little Salt

Insufficient salt allows undesirable bacteria and yeasts to compete with beneficial lactic acid bacteria.

Solution: Stick to the recommended ratio of 10 g sea salt per 500 ml water.

White Film on the Surface (Kahm Yeast)

A thin white layer occasionally forms on the surface of fermented foods.

This is usually kahm yeast, which is harmless but may affect flavour if left for too long.

Remove it with a clean spoon, check that the apples remain fully submerged, and continue fermenting.

Unlike mould, kahm yeast is:

• Flat
• Thin
• White
• Not fuzzy

Mould

Fuzzy mould in colours such as green, black, blue, or pink indicates contamination.

If mould develops, discard the entire batch rather than attempting to remove only the affected portion.

The most common causes include:

• Fruit above the brine
• Dirty equipment
• Excess oxygen

Cloudy Brine

Cloudiness often worries beginners, but it's actually one of the most reassuring signs.

A cloudy brine usually indicates active fermentation and healthy bacterial growth.

This is completely normal.

No Bubbles

Not every successful ferment produces dramatic bubbles.

If the apples smell pleasantly fresh and slightly sour, fermentation is probably progressing perfectly.

Cooler room temperatures often produce fewer visible bubbles while still creating excellent results.

Serving Suggestions

One of the reasons we love this recipe is its incredible versatility. These lacto-fermented apples add a bright, tangy contrast to both everyday meals and special occasions.

Try serving them with:

• Cheese boards featuring mature cheddar, Brie, Camembert, or blue cheese
• Charcuterie platters
• Roast pork or roast chicken
• Grilled sausages
• Burgers and gourmet sandwiches
• Toasted sourdough
• Grilled cheese sandwiches
• Mixed green salads
• Grain bowls with quinoa or farro
• Roasted root vegetables
• Potato salads
• Egg dishes
• Homemade burgers
• Smoked fish

The sweet, savoury acidity also works beautifully with autumn and winter dishes.

Recipe Variations

Once you've mastered the basic recipe, try experimenting with different herbs and spices.

Ginger

Adds gentle warmth and fresh citrus notes.

Chilli Flakes

Perfect if you enjoy a subtle spicy kick.

Rosemary

Pairs beautifully with roast meats and autumn dishes.

Thyme

Adds delicate herbal flavour that complements the apples wonderfully.

Cinnamon

Creates a slightly sweeter version that pairs exceptionally well with cheese boards.

Fennel Seeds

Introduce gentle aniseed notes.

Turmeric

Adds earthy flavour and a beautiful golden colour.

Juniper Berries

Excellent alongside game, pork, or festive meals.

Frequently Asked Questions

What are fermented apples?

Fermented apples are fresh apples preserved using lacto-fermentation rather than vinegar. Beneficial bacteria convert the fruit's natural sugars into lactic acid, producing a tangy flavour while naturally preserving the apples.

How long do fermented apples last?

Once refrigerated, fermented apples are best enjoyed within 2–3 weeks. Always keep them submerged beneath the brine and use clean utensils when serving.

Can I reuse the brine?

Yes. Many home fermenters use leftover brine to start new vegetable ferments or as a flavourful ingredient in salad dressings and marinades. Only reuse brine from a healthy, successful ferment.

Why are my apples floating?

Fruit naturally contains trapped air, making it buoyant.

A glass fermentation weight keeps the apples fully submerged, which helps maintain ideal fermentation conditions.

Is white yeast (kahm yeast) normal?

Yes.

Kahm yeast is generally harmless and commonly appears during fermentation.

Simply skim it off, ensure everything remains below the brine, and continue fermenting.

How do I know fermentation is successful?

Successful fermentation usually shows several signs:

• Pleasant tangy aroma
• Slightly cloudy brine
• Crisp texture
• Mild acidity
• Small bubbles (sometimes)

If the apples smell fresh and pleasantly sour, the fermentation is typically progressing well.

Can I ferment apples without a fermentation weight?

Yes, but it becomes more difficult to keep every apple slice submerged.

A fermentation weight greatly improves consistency and reduces the likelihood of spoilage.

Which apple varieties work best?

Firm apples work best because they remain crisp throughout fermentation.

Excellent choices include:

• Pink Lady
• Braeburn
• Gala
• Jazz
• Elstar
• Honeycrisp (where available)

Avoid very soft or mealy varieties.

Why We Used the Pearl Jars Fermentation Kit

Throughout this recipe, we used the Pearl Jars Fermentation Kit because it makes home fermentation simpler and more reliable, especially for beginners.

The reusable glass fermentation jar is non-reactive, easy to clean, and perfect for acidic foods like fermented fruit. The glass fermentation weight keeps every apple slice safely below the brine, while the airlock lid allows carbon dioxide to escape without letting excess oxygen into the jar.

Together, these tools help create ideal fermentation conditions and remove many of the common challenges that beginners experience.

If you're planning to explore homemade fermentation beyond this recipe—whether it's sauerkraut, kimchi, fermented carrots, garlic, or seasonal vegetables—a dedicated fermentation kit is a practical investment that you'll use again and again.

Shop the Fermentation Starter Set

Fermented Apples with Mustard & Garlic are proof that fermentation doesn't have to be complicated. With just a handful of everyday ingredients, a simple salt brine, and a reusable glass fermentation jar, you can transform fresh seasonal apples into a delicious sweet-and-savoury preserve full of character.

Whether served on a cheese board, alongside roasted vegetables, tucked into sandwiches, or added to hearty grain bowls, these apples bring a bright, tangy flavour that elevates countless dishes.

For beginners, this recipe is an excellent introduction to the world of lacto-fermentation. Once you've experienced how easy and rewarding it is, you'll soon be experimenting with fermented vegetables, garlic, kimchi, and many other homemade preserves.

If you're ready to continue your fermentation journey, the Pearl Jars Fermentation Kit provides everything you need to create reliable, successful ferments with confidence—from crisp fermented apples to countless other seasonal recipes.