Hi, I'm gonna say it right off the bat that I'm a noob. I Noticed no one was drinking an unopened bottle of Meijer's one gallon cranberry juice in the cubbord. I looked on the label and it didn't say it had preservatives in it so I threw in some yeast and put on an air lock. Its been 3 days and I'm seeing no activity. Are cranberries a natural preservative?