Fermented applesauce is ordinary homemade applesauce that’s been cooled, given a spoonful of live culture, and left at room temperature for a day or two. It turns slightly tangy – a little like apple yogurt – and, because it isn’t heated again, it contains live bacteria. The recipe card below uses whey strained from plain live yogurt as the starter and a 24–48 hour ferment.
How It Works, and What Can Go Wrong
Lactic acid bacteria from the starter turn some of the apples’ sugar into lactic acid. Applesauce is already acidic – about pH 3.1–3.6 (K-State pH chart) – so this isn’t a ferment that makes a risky food safe; it’s about flavor and live cultures. The problems with fruit ferments come from yeasts and molds, which like acid and sugar too:
- Yeasty, boozy or very fizzy: yeasts have taken over and are making alcohol. Ferment for less time, somewhere cooler, and use a starter so lactic acid bacteria get ahead.
- Mold: fuzzy spots of any color mean discard the whole jar – don’t skim fruit purées.
- Thin white film: usually kahm yeast; with a soft purée it’s hard to remove cleanly, so if it’s more than a trace, start again.
That’s why the card uses a starter, a short ferment and prompt refrigeration. A day at room temperature gives a gentle tang; two days a clear yogurt-like sourness.
Starters
- Whey (recommended): strain plain yogurt with live cultures through a coffee filter in the fridge for a few hours; the yellowish liquid is whey, and what’s left is thick labneh. Or make your own yogurt.
- A probiotic capsule: works, but you don’t need one.
- No starter: cooked applesauce has few microbes left, so a wild ferment is slow and more likely to go yeasty. We don’t recommend it.
Flavors
- Cinnamon spice: 1 tsp cinnamon, ¼ tsp each nutmeg and ginger, a pinch of cloves.
- Vanilla: 1 tsp vanilla extract and a pinch of cardamom.
- Mixed berry: cook 1 cup berries and 1 tbsp lemon juice with the apples.
The apples are sweet enough to ferment without added sugar. If you sweeten it, maple syrup works. Never give honey to a baby under 1 year old – it can contain the bacteria that cause infant botulism (CDC).
For Children
For older children, fermented applesauce at the 24-hour stage tastes much like plain applesauce. For babies under one, people who are pregnant, and anyone with a weakened immune system, ask your doctor or pediatrician before offering foods with live cultures, and keep it honey-free. Fermented applesauce doesn’t have proven health effects beyond what’s known for fermented foods in general (Marco et al., 2021); unsweetened applesauce itself is about 42 kcal and 1.1 g fiber per 100 g (USDA). For fizzy apple ferments, see Asturian sidra natural. For a berry version, see fermented mixed berries. Strawberries get their own short ferment in our strawberry compote.
