Yoghurt Culture

Put a well cleaned thermos flask full of hot boiled water, in order to sterilise and to warm it. Use a litre of sterile milk or heat a litre of fresh milk up to 90 °C and afterwards let it quickly cool down, for example by stirring the pan in a bowl with cold water. 1 packet of starter has to be dissolved in 1 litre of milk. Mix a cup of the sterile milk and the culture very well, pour out the hot water from the thermos flask and put the culture solution with the rest of the milk (temperature of the milk should be 45 °C for yoghurt culture). Then close the flask in order to prevent contamination.