My first sour project is just about sour enough to pull a portion from my 15 gallon oak barrel. I had planned to pull about 5 gallons and replace it with fresh beer. However, I don't have a batch ready. What I do have is about 15 pounds of frozen plums from my tree from last season. I'm thinking about pulling just the volume that I can replace with plums. Does this seem feasible? I suppose the plum detritus would be in the barrel indefinitely, but I'm not sure that would be a problem. Any thoughts?