There does not appear to be any preservatives in thier products...the smoothies do have soy/almond protein. Not sure how that would play out in a mead. Others with ore knowledge would know...of course...
I did this in a one gallon batch recently, I used 3lbs of honey, Blue Machine, and then added strawberries, raspberries, blueberries, blackberries and sweet black cherries. its been nearly a month and it is looking and tasting great.