Fermenting

Controlled microbial activity transforms food through bacteria, yeast, or mold. Fermentation preserves food, increases nutrition, adds complex sour/tangy flavors, and creates probiotics.

When to Use This Technique

Making yogurt, kefir, and cultured butter
Kimchi and sauerkraut
Sourdough bread
Miso, kombucha, idli/dosa batter

Temperature Guide

Temperature Range

65-75°F / 18-24°C for most lacto-ferments

Visual Cue

Bubbles forming in jar = active fermentation

Readiness Test

Taste daily — tangy flavor deepens over time

Step-by-Step Instructions

Start with clean equipment — wash but don't use antibacterial soap (kills beneficial bacteria)

Tip

You want native bacteria from the food and environment to colonize

Make brine: 2% salt by weight (20g salt per 1kg water)

Tip

This salt concentration encourages Lactobacillus while inhibiting harmful bacteria

Prepare vegetables, massage with salt until they release liquid

Tip

For sauerkraut/kimchi: squeeze until enough brine covers the veg completely

Pack tightly into jar, submerge under brine, weigh down

Tip

All food must stay below liquid level — exposure to air causes mold

Common Mistake

Letting vegetables float above brine is the most common source of mold

Cover with cloth and rubber band — allow gas to escape

Tip

Use airlock lids or burp jar daily if sealed to prevent pressure buildup

Ferment at room temperature 1-7 days, tasting daily

Tip

1-2 days: mild. 3-4 days: medium. 5-7+ days: very sour. Stop when you like the flavor.

Move to refrigerator to stop fermentation and preserve

Tip

Cold slows fermentation but doesn't stop it entirely — flavor continues slowly developing

Visual Cues to Look For

Bubbles = active fermentation (good sign)
Cloudy brine = Lactobacillus working (normal, not bad)
White residue on top of brine = kahm yeast (harmless, skim off)
Colored or fuzzy mold = discard batch

Equipment Needed

Glass jars or crocks
Salt (non-iodized)
Weights to keep food submerged
Cloth covers or airlocks
Thermometer

Related Techniques

picklingcuringbrining

Quick Reference

Difficulty

Hard

Time Required

1 day to several weeks