Why does the concentration of Vitamin C decrease over time?

Would there be a higher Vitamin C content in Freshly sueezed pineapples or in canned pineapple juice? why?

Why does the concentration of Vitamin C decrease over time?
Because it's an unstable compound, it breaks down over time as it's exposed to heat and air. This is a big problem with most fruit juices since they tend to be concentrated by boiling before being shipped, then reconstitued with water before being sold. An awful lot of fruit juice manufacturers actually add Vitamin C to their products to match up with people's idea that all fruit has vitamin C in it.
Reply:Vitamin C is water soluble and heat labile.





Canned pineapple juice has preservatives which could decrease the Vitamin C content over time - because of time spent from when it was freshly cut -- to the time it spent in the factory -- to the time it came to the market -- to the time it went off the shelf -- to the time you actually ate it.





Fresh pineapple has it all intact for obvious reasons.
Reply:once a plant is cut from the vine it loses vitamin content because its dying..cooking canning freezing all helps in depleting the vitamin source
Reply:Vitamin C is a water-soluble nutrient essential for life, used by the human body for many purposes. It is one of a number of such key nutrients called vitamins.





To the best of scientific knowledge, all animals and plants synthesize their own vitamin C, except for humans and a small number of other animals, including, apes, guinea pigs, the red-vented bulbul, a fruit-eating bat and a species of trout. This has led a minority of scientists, most notably Linus Pauling to conclude that failure to produce the chemical by an animal species is a genetic defect and to hypothesize that if it were replaced in humans to the level found in animals better health would result.





Vitamin C was first isolated in 1928, and in 1932 it was proved to be the agent which prevents scurvy. In 1937 Albert Szent-Györgyi was awarded the Nobel Prize in Medicine for this feat.





Vitamin C is a weak acid, called ascorbic acid or ascorbate (an L-enantiomer of ascorbic acid; an L-enantiomer is simply one of two mirror image forms of the same chemical molecular structure, see optical isomers). The active part of the substance is the ascorbate ion, which can express itself as either an acid or a salt of ascorbate that is neutral or slightly basic. Commercial vitamin C is often a mix of ascorbic acid, sodium ascorbate and/or other ascorbates. Some supplements contain in part the D-enantiomer, which is useless but harmless. See the ascorbic acid article for a full description of the molecule's chemical properties.
Reply:Because vitamin c is an acid. All acids break down.
Reply:Vitamin C , otherwise known as ascorbis acid , is a water-soluble vitamin. So processing the vitamin leads to a decrese in the concentration.