If you buy juice in a store it has almost certainly been pasteurized or HPP’d. The FDA states that all juice that is to be distributed must be pasteurized or HPP’d, it’s the law.
Now pasteurization has been around for years. In case you didn’t know, the juice is heated to a very high temperature short a vey short time, then cooled rapidly. This effectively kills any bacteria in the juice, but at the same time wipes out most of the nutritious benefits of the juice too.
Understandably this has never been a popular for real juice enthusiasts, so things seemed to be getting better a few years ago when HPP (High Pressure Processing) came along. HPP works by putting bottles of untreated juice into a high-pressure chamber full of cold water, then increasing the pressure massively, equivalent to the bottom of the ocean, which enables to juice to be stored for somewhere up to 45 days. There is no conclusive evidence to show to what extent HPP damages the enzymes and nutrients in juice, but some numbers thrown around suggest that HPP kills up to 20% of nutrients and up to 80% of enzymes. However it should be noted that these figures are from tests done immediately after the juice has been HPP’d. The reading surely won’t be as good after the juice has been sat on the shelf for 45 days.
So what about untreated juice? Well if you go to a juice bar and the sell-by date on the bottle isn’t more than a few adys away, you can be quite sure it hasn’t been treated and will therefore contain all the nutrients and enzymes that nature intended. Same goes for home-made juice. If you use a good quality slow juicer the juice you make at home will really be the best you can get. Drank straight away, untreated juice has the very best health benefits you can get from juice.