Many people hesitate to boil the dairy milk for different reasons, however what are benefits of boiling when you make yogurt and kefir at home.
1. The boiling of the dairy milk kills competitive bacteria in the milk – this guarantee that there is no number of competing bacteria present. Most of the milk nowadays is pasteurised in advance before to reach the shelves in the shop as the focus is on removing the bacteria harmful for the people, but a small number of bacteria still exist after the process. They are not dangerous for the people, but they might get in competition for food with the yogurt and kefir bacteria in the starter. This will increase the time for incubation and also will compromise the starter in a long run which consequently will reduce the number of the recultivations you are able to do.
2. Boiling of the milk evaporate the water in the milk. All milks contain some water. After the fermentation you will notice some whey left. This whey actually is the water in the milk, and the best way to remove it in advance is to boil the milk for 15-20 min. Surely you can remove the whey after the fermentation is completed and strain the yogurt for a few hours.
3. The boiling also breaks down some enzymes in the milk and thicken the solids. This additionally supports the thickening of the milk during the fermentation as practically helps the lactobacteria in doing the job and consequently this can reduce the incubation time.
There are two main ways to boil the milk
1. On the stove – this actually is the way people try to avoid. It takes time and need constant attention as the milk can burn or overflow especially if try to maintain long boiling process.
2. In the microwave on full power for 15-20 min. – This way is one of the easiest. You need a flat container sized at least double the amount of the milk to avoid overflow and nothing else.
Many people are also wondering if they should boil ultra pasteurized milks – the answer is simple – not every time, but if you made a yogurt and there is excessive amount of whey, please do it for the next batch. The standards and technologies for this are different, and the milk might contain water or amount of competitive bacteria( harmful to the bacteria in the starter but again not harmful to the humans) after processing is completed.
Another important element is about boiling the plant based milks(coconut, almond and soy). Please note that all these kind of milks are actually kind of juices(or cold tea) and boiling will destruct them completely - please avoid any boiling of the plant based milks, but always keep them lukewarm when adding the starter and during the incubation.