Pomegranate Lager

[Lawnchair_Ninja (Larkin Vander Mel)]

I am brewing a lager and I would like to add fresh (from our tree) pomegranate juice to it when I move the beer to the secondary fermentation.  My questions are how much juice to add to five gallons of beer and should I boil the juice and let it cool before adding?  I don’t want the beer spoiled by bacteria or anything else.