Instructions: Given the background description of some cooking related query, summarize the question into a title
Input: When I make yogurt, I freeze some of the yogurt for the next time. However, I concentrate the yogurt by pouring it into a cloth, and extracting the yogurt whey (I do not know if it is called whey like cheese).Is the culture in the yogurt whey? Do I lose culture by concentrating the yogurt?Is salt harmful for the culture? Do I necessarily need to store the culture before adding salt to yogurt?
Output:
How to catch culture out of yogurt?