I made a cooked rhubarb filling that has rhubarb, sugar, lemon juice and a vanilla bean. Does this need to be refrigerated? I was going to make a yellow cake with rhubarb filling and was hoping to do it ahead of time. Since it's a pretty big cake, I definitely don't have refrigerator space to accommodate this so I was wondering if it would be all right to leave it out overnight? Thanks!

Yes, the sugar is a preservative. It's dairy products that are a more inclined to go bad quickly.

Thanks! I figured it would be okay but didn't want to bite into bad filling when we cut the cake...eek!