Pasteurization is used to destroy harmful bacteria, viruses and other microorganisms. Traditionally this is done by heating the juice. This makes them safe for consumption and also guarantees a longer shelf life. Unfortunately this process also destroys some enzyms, minerals and vitamins which compromises the quality to a certain degree. This doesn't mean that pasteurized fruit juices are bad, it simply means that they do not replace fresh fruits.
Juices are very practical and deliver quick energy, similar to cereal bars or coffee and coca cola without the caffeine. Like those products fruit juices should be consumed in limited amounts. They are great instead of a snack, if you need a quick energy kick but should not be consumed at the place of water and fresh fruits. Also instead of alcohol they can be delicoius alternative.
The positive site of those recent studies is that fruit juice producers have to deliver higher quality. Consumer awareness has increased and people are demanding safe quality products. This does not only include the ingredients and the manufacturing process but also the equipment used for the production.
The manufacturer of pasteurizers for fruit juices(http://www.syruproom.com/