The short answer
- Heat 1 litre of full-cream milk to 85 °C, cool it to 45 °C and stir in about 50g of plain yoghurt with live cultures.
- Ferment in jars in the sous vide bath at 45 °C for 8 to 12 hours: the longer, the firmer and tangier.
- Chill for at least 8 hours; the yoghurt sets further in the fridge.
- Vacuum sealed in its jar, homemade yoghurt keeps up to about two weeks in the fridge.
Why a sous vide cooker
Yoghurt cultures work in a narrow band of warmth: too cool and they're slow, too hot and they die. A sous vide cooker holds the water at the set temperature for as long as you like, so the jars sit at 45 °C all night without you watching them.
You need two ingredients: full-cream milk and plain yoghurt with live cultures as the starter, without added sugar, flavour or thickeners. About 50g of yoghurt per litre of milk is enough.
Fig. 20 · Milk to yoghurt
Six steps
Temperatures and times from LAVA's recipe.
Step by step
1 · Heat the milk to 85 °C
In a saucepan over medium heat, stirring so it doesn't catch on the bottom. Heating kills unwanted bacteria and changes the milk proteins, so the yoghurt sets thicker.
2 · Cool it to 45 °C
Stand the pan in a sink of cold water, stir now and then and check with a thermometer. Much hotter, and the cultures suffer.
3 · Add the starter
Stir the yoghurt smooth with a little of the warm milk first, then stir it into the rest, so the cultures spread evenly.
4 · Fill the jars
Clean, heat-resistant glass jars with lids, filled to just below the rim. Vacuum bags work too, sealed without air, but jars go straight from the bath to the fridge and the table.
Helps: Preserve jars
5 · Ferment at 45 °C
Set the sous vide cooker to 45 °C and let the bath heat up, then stand the jars in it with the water up to their shoulders. Leave them for 8 to 12 hours: 8 hours gives a milder, softer yoghurt, 12 a firmer, tangier one. A layer of insulation balls stops the water evaporating overnight.
Helps: PreserVide SmartPro · Insulation balls
6 · Chill
At least 8 hours in the fridge, without stirring: the yoghurt sets further as it cools.
Keeping it
Vacuum seal the jars
With the air drawn out of the jar, mould and bacteria grow more slowly and the yoghurt stays fresh for longer: LAVA gives up to about two weeks in the fridge. The Flex Jar-Sealer fits over jars up to 106mm wide and works with a LAVA sealer or a hand pump.
Helps: Flex Jar-Sealer · Vacuum cover for jars
Variations
- 1
Thicker, Greek-styleStrain the set yoghurt in a sieve lined with a clean cloth in the fridge for a few hours.
- 2
Other milksGoat's or sheep's milk works the same way and tastes stronger.
- 3
Keep some plainAdd fruit, honey or granola when you serve, and keep a few spoons of plain yoghurt as the starter for the next batch. When a batch turns runny, start again with fresh bought yoghurt.
Clean jars, fresh milk. Wash the jars and lids in hot soapy water or the dishwasher, and use milk well within its date. If a batch smells off, shows mould or turns pink or grey, throw it out, and don't use it as a starter.
LAVA AustraliaOfficial LAVA distributor and vacuum-packaging specialists since 2018.
