Interactive lesson

Fermentation basics, step by step

Interactive lesson: salt, vegetables, time and no air at all — how much salt, what temperature, weights, vessels, cleanliness, pH and storing the finished product.

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The whole lesson as text

1. Salt: how much and which kind

Salt is the one ingredient in fermentation that you don't change to taste.

Salt is weighed — Not by eye and not by the spoon. A kitchen scale that reads to 1 g weighs both the vegetables and the salt.
Dry salting — For shredded sauerkraut and soured turnip: 2–2.5 % of the weight of the trimmed, shredded vegetables, which is 20–25 g per 1 kg.
Brine — Whole vegetables are covered with salted water. For cucumbers 40–50 g of salt per 1 L of water, for peppers, cauliflower and mixed pickles 30–35 g.
Which salt — Best is non-iodised salt with no anti-caking agents, such as pickling and canning salt. Coarse sea or rock salt is fine, but always weigh it. Road salt and livestock salt are not food.

Why: Too little salt and the vegetables go soft or spoil before the acid builds up. Too much and the bacteria don't work, so the vegetables stay salty and never sour.

A tablespoon of fine salt holds roughly 15–18 g, a tablespoon of coarse salt 10–14 g. On 50 kg (110 lb) of cabbage the difference by eye can be half a kilo.
Don't ferment vegetables below 1.5 % salt. Anyone who must eat less salt should eat smaller portions or give sauerkraut a quick rinse before eating.

2. Temperature and time

The same cabbage is ready in three weeks in a warm kitchen and in two months in a cold cellar.

Warm at the start — The first 7–10 days at 18–22 °C (64–72 °F): kitchen, larder or a hallway next to a heated room. Fermentation starts quickly and the acid rises quickly.
Thermometer by the vessel — Not on the wall by the stove. Write the temperature in the log.
Then cooler — The rest of the main fermentation, 2–4 weeks, at 15–18 °C (59–64 °F).
Done, into the cold — A cellar, cold larder or an unheated garage that doesn't freeze, at up to 10 °C (50 °F). There sauerkraut and pickles keep until spring.

Why: Temperature decides which bacteria work and how fast. Below 15 °C (59 °F) fermentation stalls, and above 24 °C (75 °F) the vegetables go soft and may spoil.

In October and November cellars and garages are already cold (8–12 °C, 46–54 °F). Fill the crock in a warmer room and move it to the cold once the first phase is over.
A large full crock is heavy. If you have to move it, plan that before filling.