My neglected sourdough, (several weeks) developed a moldy top. What is that? If I discard it, can I refeed, and will it survive. What is the difference between "fed" and "unfed"? If sourdough doesn't bubble, is it still useable? Charles, if after feeding your sourdough several times in a couple of days, and keeping it warm, it still doesn't bubble, it should be discarded; it's dead. As for a moldy top - depends what you mean by moldy. If it had a grayish-black liquid or coating on top, just pour or scrape it off and continue. It it was pinkish, or had what you identified as actively growing mold (spongy looking, mushroom-y looking), then it would be best to discard your starter and begin again. A fed sourdough starter is one that's been fed within 8 hours or so of you using it; it'll be actively bubbly. An unfed starter is one that hasn't been fed in awhile, long enough that it's no longer actively bubbly. Hope this helps - PJH

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