Simplify the following text for a Grade 7 native English-speaking person.
Original: After it is cooled to about 45 Â C , the bacteria culture is added , and the milk is kept at that temperature for 4 to 7 hours to ferment .
Simplified: The milk is then cooled to about 45 Â C. The bacteria culture is added , and the temperature is maintained for 4 to 7 hours to allow fermentation .