I'm not worried about by vitamin C intake but the fact that it took six days to reach a relatively high level is good news. Still, the fact that there's a nutritional impact based on saving juice a short amount of time is a factor to consider. I also never thought that leaving my juice in my cup had an impact on nutrients-- I haven't done that with my blended juices but it's something I do frequently.
A 2006 issue of the “Journal of Agricultural and Food Chemistry” found that between 5 to 25 percent of vitamin C content was lost in cut pieces of kiwi, pineapple, mango, strawberry, watermelon and cantaloupe over a period of six days when the fruits were stored at 41 degrees Fahrenheit. There was also a significant loss of carotenoids.
http://www.livestrong.com/article/548978-does-fruit-lose-its-nutritional-value-when-its-blended/
But overall, fresh juice is best consumed fresh - and that means within the first twenty minutes. The reason for this is simple. Fresh juice - and all its benefits - come from its freshness. As soon as you juice fresh produce, you're breaking open the cell walls of these nutrient-rich fruits and veggies and activating the nutrients - the vitamins, enzymes, minerals, phytonutrients, chlorophyll, etc. - found in the produce.
Many of these nutrients are time-sensitive. Just as you wouldn't slice an apple, leave it out to turn brown and shrivelly and then consume it, the same logic also applies to juice.
The process that causes apples to go brown so quickly is known as oxidation, which is simply exposure to oxygen. Juice is even more susceptible to oxidation since every part of the fruit or vegetable is being exposed to air.
Oxidation is natural and it's not the worst thing in the world, but it does reduce the enzymes and vitamins in the fruit and veggie juices, defeating a large part of the point of drinking such juices. Even when there's no visible color alteration in the juice, the same process of oxidation occurs.
People commonly recommend adding a squirt of lemon juice to sliced apples or even to halved avocados to prevent signs of oxidation. Whereas this certainly helps an apple or avocado from turning really brown, really quick - the vitamin C in lemon juice (which is an antioxidant that fights oxidation) will only slow oxidation, not prevent it.
When fruits and vegetables are juiced, adding lemon juice may slow the oxidation a bit, but it won't be able to protect the integrity of the juice against exposure to the air. With prolonged exposure to air, the vital enzymes and nutrients in the juice begin to deteriorate and are mostly gone within twenty minutes time.
http://justjuice.org/when-does-fresh-juice-lose-its-freshness/
The following really made me wonder about the heat in my Vitamix-- I just blend until everything looks blended. I suppose I could cut down on blending time by cutting the food more beforehand, which sucks as far as convenience:
Keep in mind that how long fresh juice lasts depends on the juicer that you're using.
Centrifugal juicers - such as the
Jack LaLanne juicer and most of the
Breville juicers - operate a high speeds, which produce heat and introduce oxidation into the juicing process itself, compromising the freshness of the juice. Juices made with these juicers really should be consumed immediately - at most within a few hours.
To be safe, I'm going to stick to a 48 hour rule this week, maybe overnight as time allows in the future.
