How to test your dairy and non-dairy yoghurt culture.

To test to see if your culture is still active, you have two options;

 

(1)  Incubate a small amount of milk with the culture and leave it at 40 Deg C for one hour. Then compare the pH of the milk from before the culture was added to after the hour of fermenting. This requires the use of pH test paper. 

 

If using non-dairy milk for this test, ensure that there is enough sugar for the culture to ferment.

 

Steps.

• Warm one cup of milk to 40 Deg C.
• Test the pH of the milk
• Add the culture and let ferment for one hour. 
• Test the pH of the fermented/cultured milk. 
• If the pH has dropped then the culture is active as it is breaking down lactose, the sugar in milk, and forming lactic acid, reducing the pH.  

 

(2) Incubate a small amount of dairy milk at the correct temperature for 8 to 10 hours. Dairy proteins naturally bond together with increasing acidity giving a visible indication of the increasing acidity. This does not require the use of pH test paper.

 

Steps.

• Warm your milk to 40 Deg C and place in your sealed yoghurt maker.
• Add the culture and let ferment for 8 to 10 hours. 
• Examine the milk for any indication of a curd forming. If a curd has formed then the culture is most likely* active as it is breaking down lactose, the sugar in milk, and forming lactic acid, reducing the pH, and causing a curd to form.  

* Please be careful not to contaminate your milk with any other bacteria around, as this could cause a similar effect.