Storing a Starter
Our romantic image of days of yore suggests that the hard working mother of a family of 12 to 14 baked several times a day to feed herself, her hubby and the kids. And, if she was really lucky, she might also be feeding the ranch hands, the miners and the posse. (After all, what Western movie would be complete without ranch hands, miners and a posse?) In such a picture, the starter would be fed and used several times a day, and it would be very healthy. A similar situation would apply in a commercial bakery.
However, today few of us bake that often, and it's hard to justify twice-a-day maintenance of a starter we use once a week or once a month. Surely, there has to be a better way.
Well, maybe not a better way, but certainly a viable way. The answer is the refrigerator.
Some people feel refrigeration destroys a starter. Several sourdough experts feel that if a starter gets below 46F, it should be discarded and you should start over. I have not had that experience, though I will say you have to be careful when refrigerating starter.
Dr. Sugihara, the scientist who discovered how San Francisco sourdough works also studied freezing sourdough. His studies seem to transfer over to refrigerating starter. In general, a starter that was fed just before it was refrigerated or frozen seems to bounce back faster than a starter that was mature when it was put in storage.
Some people seem to feel that refrigerating their starter is some sort of goal. I can't count how many letters I've received that ask if it's OK to refrigerate their less-than-a-week old starter yet. It is important to understand that a new starter is building in strength and flavor for somewhere between 30 and 90 days, depending on who you read and believe. As a result, I don't recommend refrigerating a starter until it has had time to reach its peak potential.
So, when can you optimally refrigerate a starter? The starter should be at least 30 days old, having been fed twice a day the entire time. It should be able to make bread you like - why store a starter that isn't working for you? A starter you get from a vendor, friend or other source is already more than 30 days old, the 30 days just refers to starters you have started. Next, the starter should be able to double its size between feedings. If it's not healthy, it's not a good idea to refrigerate it. And finally, the best time to refrigerate the starter is when it is freshly fed. So, feed your starter until it will double in size between feedings, feed it one more time and then refrigerate it. I call the starter in the refrigerator my "storage starter."
Refrigeration is not a science-fiction suspended animation. Your storage starter will probably double in size while in the refrigerator over a period of a few days, so remember not to overfill your storage container. Also, when in refrigerated storage, your storage starter will be in a state of slow decline. The storage starter will need to be fed from time to time. I do not suggest leaving a storage starter in the fridge for more than two months without feeding it and reviving it. We'll talk more about how and why to do that in "reviving a starter."
A common question at this point is, "what sort of container should I use to store my starter?" I like wide-mouthed glass canning jars. They hold a lot, they are covered, they are durable and they are cheap. I usually don't seal the top tightly. I've heard horror stories about a starter building up so much gas pressure in a jar that it explodes. I'd rather not find out if that could happen, so I close the lid loosely. Plastic tends to scratch too easily, so it isn't as easy to clean. While I have no problem with metal utensils and bowls, I'd rather not use metal containers for long term starter storage.