Homemade yoghurt, easy and cheap!

Yoghurt is another of the dishes I started to make to reduce my own waste.
As I like to have dessert after a meal, I was actually collecting more than enough yoghurt pots to make homemade soap ;) (if you don't understand this joke, see "how to make soap" articles).

Making yoghurt is quite simple and cheap.
You don't even need a yoghurt-machine, you can use an oven.
Regarding the ingredients, just milk, and a yoghurt that will ferment the milk and transform it into yoghurt.
And also anything else to flavor it (honey and jam for example).

Quality is important here, both for the milk and the yoghurt.

Milk

Choose full-cream milk.
It doesn't need to be cow milk; it can be any other animal milk.
Vegetal milk too. I tried with soya milk (Go green, I haven't tried with Alpro) and it works, but I hear that with other vegetal milk you need thickeners.


Yoghurt as a "starter"

First you will need to buy a yoghurt, and then you can reuse one of yours.
A cow-milk yoghurt can be reused about 6 times before the ferments stop working.
A soya-milk yoghurt can be reused up to 15 times.
The thicker a start yoghurt is, the thicker yours will be as well.
A solution to get a thicker yoghurt is to filter it: use a cloth in a strainer and most of the water will go away.

I've had good results with Greek yoghurt, as well as Yoplait and Tine yoghurts (but not as firm as what I'm used to in France though).

Regarding soya yoghurt, I failed several times.
It never worked with alpro yoghurt, and it worked once out of twice with Soyesse (found at Coop Obs).
It actually worked with the plain version, and not with the strawberry-flavored yoghurt.
It could be the list of ingredients is different. It could also be something else failed in the process.

A good way to check a soya yoghurt is usable as a starter is to make two batches at the same time, one with a cow-milk yoghurt, especially one you have used before and you know works.
Yes, cause you can mix soya milk and cow-milk yoghurt. I got a pretty good result with Greek yoghurt.

***

Now, enough with the introduction, here comes the recipe and the modus operandi :)

You need about 100 grams yoghurt for 1 Liter milk.
Then it's all about temperature.


Heat the milk. It has to be at a temperature of about 50° C, not more.
If you don't have a thermometer, here is a tips: boil half of the milk and then mix it with the other - cold - half.

 

If it's the right temperature you should be able to dip your little finger for about ten seconds.
If so, take it off the stove and pour the yoghurt.

Another tips: with a thin layer of water in the pan will prevent the milk from sticking to it.

Mix well and pour in glass jars. I think it works as well if you just put the same quantity in small jars same size and then pour the milk.

Put the jars in a large dish and cover almost completely with water (3/4).
Then put in the oven which has to be at maximum 100° C.
Turn it off and don't open it for at least 6 hours. The whole night is perfect.

I usually make yoghurt after I have used the oven to cook something else. I then use the residual heat and let the oven cool down by itself. I told you, it's cheap!

I've also read about another method that uses even less heat:
Wrap the jars in a blanket and leave it by the radiator for 24hours, or even outside during summer. Well, not in Tromsø ;) It works with a temperature of 20 °C.

Bon appétit !