Juicing and storing it...

Xiaolongbao

I've recently moved to a country where fruit and veg are really cheap so I thought I'd try out juicing. All the stuff I read says you need to drink the juice straight away but I haven't found any reputable links that explain what the actual effect of not doing that is. Ideally what I'm after is information over what percentage of all the good stuff is left after various periods of time. Anyway know any place?