*dreamer* Posted November 16, 2005 Share Posted November 16, 2005 Hi! Can anyoe tell me what affect uv light have on the vitamin c content in lemon juice. please i realy need help on this...thnx Link to comment Share on other sites More sharing options...
RyanJ Posted November 16, 2005 Share Posted November 16, 2005 Hi! Can anyoe tell me what affect uv light have on the vitamin c content in lemon juice. please i realy need help on this...thnx Not much effect I would think unless you are close to the sun and the temperature is above 175°C at which point itwill start to decompose Links: http://en.wikipedia.org/wiki/Citric_acid Cheers & Welcome to the forums! Ryan Jones Link to comment Share on other sites More sharing options...
*dreamer* Posted November 16, 2005 Author Share Posted November 16, 2005 thnx ryan. wot about the effect on ascorbic acid (which is present in vit c)..i would be using a uv lamp to carry out this investigation. Link to comment Share on other sites More sharing options...
RyanJ Posted November 16, 2005 Share Posted November 16, 2005 thnx ryan. wot about the effect on ascorbic acid (which is present in vit c)..i would be using a uv lamp to carry out this investigation. Well, actually ascorbic acid (2-oxo-L-threo-hexono-1,4-lactone-2,3-enediol) is more stable than citric acid (2-hydroxy-1,2,3-propanetricarboxylic acid) and decomposes above 192°C instead of 175°C As for the exact effects of exposure to UV radiation I am not shure. I can find little informaiton on the subject after some research. Maybe a little Googling will trun up some more useful results and more informaiton than I can provide! I suppose the UV light could encourage the substance to decompose but I'm really not shure sorry Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
Douglas Posted November 16, 2005 Share Posted November 16, 2005 Hi! Can anyoe tell me what affect uv light have on the vitamin c content in lemon juice. please i realy need help on this...thnx I've read that a glass of freshly juiced orange juice looses 50% of it's vitiman C after 20 minutes of exposure. Link to comment Share on other sites More sharing options...
RyanJ Posted November 16, 2005 Share Posted November 16, 2005 I've read that a glass of freshly juiced orange juice looses 50% of it's vitiman C after 20 minutes of exposure. it does? In that case it could be UV does have an effect, causing the cutric acid or some of its compoents to decompose. the actual question is what is actually causing this effect and how cna you be shure it is the UV light? Your experiment should find this out. Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
Douglas Posted November 16, 2005 Share Posted November 16, 2005 it does? In that case it could be UV does have an effect' date=' causing the cutric acid or some of its compoents to decompose.the actual question is what is actually causing this effect and how cna you be shure it is the UV light? Your experiment should find this out. Cheers, Ryan Jones[/quote']The juice people claim that a sliced apple or potato will turn brown in 20 minutes, thus oxidation, they claim that the same oxidation depletes the C from the orange. Link to comment Share on other sites More sharing options...
RyanJ Posted November 16, 2005 Share Posted November 16, 2005 The juice people claim that a sliced apple or potato will turn brown in 20 minutes, thus oxidation, they claim that the same oxidation depletes the C from the orange. Good point. Funny thing though, Citric acid is supposed to be an anti-oxidant so if you apply it to something like the potato slice it should oxidise more slowly than one without it applied Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
insane_alien Posted November 16, 2005 Share Posted November 16, 2005 err isn't vit C ascorbic acid and not citric acid. just seeing as i did a titration today with ascorbic acid and the header said Vit C Titration. Link to comment Share on other sites More sharing options...
RyanJ Posted November 16, 2005 Share Posted November 16, 2005 err isn't vit C ascorbic acid and not citric acid. just seeing as i did a titration today with ascorbic acid and the header said Vit C Titration. It is, My mistake... Sorry about that! Vitamin C is a weak acid' date=' 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-entantiomer, which is harmless but useless. See the ascorbic acid article for a full description of the molecule's chemical properties. [/quote'] http://en.wikipedia.org/wiki/Vitamin_C Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
*dreamer* Posted November 17, 2005 Author Share Posted November 17, 2005 hey guys....after talking to some of my teachers, i THINK that uv gives energy to d ascorbic molecules...making them unstable and eventually break down...the thing is i dont understand what it would break down to! so far googling has brought up anything new! Link to comment Share on other sites More sharing options...
Aubiegirl Posted November 18, 2005 Share Posted November 18, 2005 I'm not sure about citric versus ascorbic acid or anything like that, but when I had guinea pigs (which, like humans, need to get vitamin C from their diet instead b/c they can't make it themselves) all the books and everything said to pay attention to the packaging dates on their food and to store it in opaque containers, because after too long the vitamin C would degrade. Just thought I'd toss that in as a real world example. Isn't there something similar with milk? Is it the vitamin D that is supposed to be protected by the opaque jugs? Link to comment Share on other sites More sharing options...
Douglas Posted November 18, 2005 Share Posted November 18, 2005 . Isn't there something similar with milk? Is it the vitamin D that is supposed to be protected by the opaque jugs?That could be, from what i've heard, they put beer in translucent bottles to keep it from going bad, Link to comment Share on other sites More sharing options...
*dreamer* Posted November 18, 2005 Author Share Posted November 18, 2005 thnxxx everyone....i think the info i have will be enuf Link to comment Share on other sites More sharing options...
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