you have nothing to worry about. think about all the air that is in Winny when you inject that. you need about 3 ccs of air to be injected to be harmful.
My friend is a nurse and told me to put a little air bubble it .So when you inject allow the juice to go in first and the thrust of the air bubble at the end will push all the juice in there.If you ever get some juice that leaks out after injecting this will prevent it