At Sinplastico we try to offer alternatives and advice for those looking to live a zero waste lifestyle. Today we are sharing our recipe for how to make yoghurt without a yoghurt maker.

What is yoghurt?

Yoghurt is a dairy product made via the bacterial fermentation of milk. Fermentation of lactose (the sugar present in milk) into lactic acid is what gives yoghurt its distinct texture and flavour.

Yoghurt needs to go through the fermentation process at 43°C to achieve the optimal degree of acidity. Maintaining a temperature between 40°C and 50°C will ensure the right texture and acidity is achieved.

Once the yoghurt is made, it should be cooled to 5°C to stop fermentation from continuing.

To make home-made yoghurt without a yoghurt maker, we need an incubator, the yoghurt mixture and a heat source.

Preparing the incubator.

Firstly, we need an alternative to this small electrical appliance, the yoghurt maker. A yoghurt maker is simply an electrical appliance that keeps the yoghurt mixture at a constant temperature during a specific period of time.

For this we need to find a container that is sufficiently insulated so that it can maintain a constant temperature during 8 hours:

  • Our favourite option for making home-made yoghurt is to use 2 cardboard boxes (one inside the other), and to insulate them, we fill the gap with old jumpers, scarves or remnants of wool (one of the best natural thermal insulators) or cotton.

  • Another option is to give a second use to your portable fridge or cooler, the ones you take to the beach or on a picnic.

  • Finally, you can also re-use polystyrene boxes from the fishmonger or greengrocer (unfortunately they are often still used) or the boxes used for transporting medicines to and from pharmacies (they usually have a middle layer of polyurethane).

Making the home made yoghurt mixture

Once our DIY yoghurt maker is ready, we just have to prepare the mixture.
For this we need:

  • Yoghurt (125-150ml per litre of milk). This recipe makes yoghurt by the litre.

  • We recommend that you choose both organic yoghurt and organic milk.

  • Put the mixture in a saucepan and heat it gently (patience is a virtue, and it’s essential here), meanwhile we stir the mixture with a whisk, a fork or a spoon.

  • Heat it up until 43°C is reached. To know when the mixture is ready you can use a cooking thermometer or stick your finger in the mix. When it starts to burn your finger, after holding it in the liquid for 10 seconds, it is ready.

  • Once the yoghurt mixture is ready, reduce the heat to minimum to maintain the heat whilst you fill the pots. We really like the Weck pots because they come with a glass lid.

 The heater

To keep the mixture at this ideal temperature of 43°C for 8 hours, we need a little extra help. For this:

  • Boil some water (whilst you are making the mixture, so that you can continue the process without delay) and put it in a pot, jar or glass bottle (depending on the size of your thermal box/incubator)

  • We make 3 litres of yoghurt at a time and therefore use 2 x 300ml pots that we put equidistant in the corners of the box.

…and Voilà!!!

  • We put the mixture into closed glass pots (that are not cold so that the mixture doesn’t lose its heat)

  • We arrange everything in the box, the pots filled with the yoghurt mix and the heater/s (jars filled with boiling water).

  • Close the box well, don’t let the heat escape, and you’re ready!… Leave the bacteria alone to do its work for the next 8 hours. We have done some tests with more and less time and found that 8 hours is the ideal time period.

Tricks of the trade

  • Whatever milk you prefer will work (cow, sheep, goat…), but remember that the bacteria “eat” the sugar in the milk, so if you use skimmed/low-fat milk the yoghurt is likely to have a more runny texture.

  • The mixture should be in the yoghurt box for 8 hours. Therefore, it’s a good idea to make it in the evening and the yoghurt will be ready in the morning. It is best to set an alarm to remind yourself to remove the yoghurt from the box.

  • After filling the pots with yoghurt, you can warm them by putting them in a container filled with hot water for a few seconds.

  • And remember! You will need some yogurt for next time, do not eat it all!