Unfortunately, this happens if you blend it for too long. So try not to go crazy blending this. Also, this drink is best enjoyed the day it's made. The longer it sits, the more bitter it can get. This drink is definitely not for everyone. it does have just a touch of bitterness to it that some people will not enjoy, so if that is not for you then you may not like this drink. See my FAQ below about other ways to help with the bitterness.