Before You Start

Set up your precision cooker or adjustable yogurt maker and confirm it can hold a low, steady 97–100°F (36–38°C). This is the single most important factor: ordinary yogurt makers and Instant Pots run at 108–115°F or hotter, which kills L. reuteri before fermentation even begins. If you can, verify the real temperature with an independent thermometer rather than trusting the device readout.

Optional: Firm Up the Set

For a thicker, less-splitty yogurt, gently heat the milk to about 180°F (82°C), hold for 10–15 minutes, then cool it back down to around 100°F before you inoculate. If you're using UHT / ultra-pasteurized milk, you can skip this step — it's ready to use as-is.

Make the Starter Slurry

Empty one MyReuteri capsule (or crush 10 BioGaia Gastrus tablets to a fine powder) into a bowl. Add 1–2 tablespoons of inulin or prebiotic fiber and about 2 tablespoons of your milk. Whisk vigorously until completely smooth. This slurry step prevents clumping and spreads the culture evenly through the batch.

Combine and Jar

Stir the remaining milk into the slurry until fully blended. Pour into clean wide-mouth glass jars and seal with plastic — not metal — lids, which can react with the acidic yogurt.

Ferment Low and Slow

Place the jars in your water bath at 97–100°F and ferment for 36 hours. Keep the bath water below the lid line, or leave the lids slightly loose, so the small amount of gas can vent. Don't cut it short — L. reuteri growth accelerates most after the first 24 hours.

Chill and Set

Refrigerate the jars. The yogurt continues to firm up as it cools and is usually perfect by the next morning. For a Greek-style texture, strain it through cheesecloth for 4–6 hours.

About Your First Batch

If your first batch separates into curds and a layer of whey, that's completely normal — it's the bacteria waking up from dormancy, and the yogurt is still fully potent. Just whisk it smooth. Then use 2 tablespoons of it to seed your next batch, which will come out noticeably thicker and creamier. You can re-culture this way for roughly 7–10 batches before starting fresh.