Unless you are making yogurt daily and eating it all up, there are times you will want to store yogurt or the cultures for days, weeks, or even months.
The reusable cultures we send to you are freeze-dried in our commercial kitchen, and vacuum-sealed for shipping. They should be viable in the box for about a month at room temperature. Since they are freeze-dried, additional cold storage will not harm them and they will be good in the refrigerator or freezer for about 9 months.
Direct-set cultures should remain viable for about 12 months in the freezer.
Once your yogurt has been made, you can keep it in the refrigerator for a couple of weeks at least, just like store-bought yogurt. There may be some separation, and whey can appear at the top of the yogurt. This is not a problem, and you can pour it off and either save it for cooking or throw it away, or you can stir it back in to the yogurt.
If you are going to use some of the yogurt for making another batch, we recommend doing so within 5 to 7 days to ensure the cultures remain viable.
If you want to take a break from making yogurt, you can preserve some active cultures by freezing or drying. Neither method is completely reliable, but our customers report a fair amount of success with either.
Freezing Yogurt Cultures
Put some fresh, active yogurt in clean ice cube trays. For each cube, use the amount of yogurt that it will take to culture 1 cup of milk. When the cubes are frozen, put them in an airtight container in the freezer. When you’re ready to make yogurt, take out as many cubes as you’ll need (1 cube per cup of milk), and let them thaw before adding them to the prepared milk. It’s best to use these within a month for best results.
Drying Yogurt Cultures
Spread a small amount of starter on a piece of unbleached parchment paper. Leave the yogurt or buttermilk to dry in a warm, safe spot no more than 80°F. Once it is completely dry, store in a zip lock bag in the refrigerator. Under ideal conditions, the starter will keep for up to a few months. To rehydrate the yogurt or buttermilk, grind up the dried starter and place one teaspoon dried yogurt in a cup of milk that has been prepared according to the instructions for activation for the type of culture you’re using. Mix well to fully incorporate. Culture as you normally would but keep in mind that this rehydrated batch will generally take twice as long to culture: 8 to 12 hours for thermophilic (heated) yogurts and 24 to 48 hours for mesophilic (counter-top) varieties.