Sulphur dioxide in food

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Offline DoctorBeaver

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Sulphur dioxide in food
« on: 05/01/2009 22:06:20 »
I bought some periperi chicken for dinner today. As I'm not allergic to anything (except children) I don't normally bother reading the ingredients or warnings. However, for some reason I decided to this time. I must admit I was somewhat surprised to find my fiery fowl fare contained sulphur dioxide.

I'd never heard of that as a food additive so I decided to check it out on the internet. To my surprise I found out that it's 1 of the most common additives.

Not being of a chemical bent, if someone had asked me about sulphur dioxide I would probably have said it's poisonous, not a "versatile food additive" as it was described on 1 particular site.

Is anyone else as ignorant of this as I, or does everyone know about it?
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Offline Chemistry4me

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Sulphur dioxide in food
« Reply #1 on: 06/01/2009 00:07:08 »
The following properties of sulfur make it useful as a commercial chemical:
It is very soluble in water at room temperature. The process of dissolving is:

SO2 (g) + H2O (l) → SO2 (aq)

This process is reversible - when sulfur dioxide gas escapes from water, the choking smell of the gas can be noticed  [:o].
The SO2 gas can combine with oxygen slowly at room temperature - i,e. it can act as an antioxidant. An antioxidant prevent the oxidation of other substances because it removed the oxygen that would be needed for oxidation.
This property makes it a good food preservative (e.g in drinks/wines)
Sulfur dioxide is dissolved in the water of fruit juices and wines to remove microbes that can alter the taste and produce toxins. Like all living organisms, microbes require oxygen for respiration. Sulfur dioxide in the beverages removes the oxygen present and thus the microbe is distroyed.  [xx(] [xx(] [xx(]

I suspect Doc that the sulphur dioxide in your chicken was used as a preservative. [:)]

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Offline DoctorBeaver

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Sulphur dioxide in food
« Reply #2 on: 06/01/2009 11:11:39 »
Chemistry4Me - thank you for that reply. You've explained it nicely. I was just taken aback a bit as I hadn't realised it was used in foodstuffs. I really should read the labels more often  [:I]
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Offline Bored chemist

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Sulphur dioxide in food
« Reply #3 on: 06/01/2009 17:41:10 »
"Like all living organisms, microbes require oxygen for respiration. "
Oh no they don't. (Is the Xmas panto season over yet?)
However SO2 is quite reactive so, since it can react with important chemicals in cells, it's toxic.

Incidentally, re. "if someone had asked me about sulphur dioxide I would probably have said it's poisonous"; can you tell me which chemicals are not poisonous?
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blakestyger

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Sulphur dioxide in food
« Reply #4 on: 06/01/2009 18:19:39 »
It's used a lot to sterilise glassware before bottling - as Campden tablets; I used to use this when home brewing years ago. I've had German white wine in the past where the SO2 was so concentrated I could smell it. It's also used in preserving dried fruit, such as apricots.

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Offline Make it Lady

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Sulphur dioxide in food
« Reply #5 on: 06/01/2009 18:25:09 »
I had periperi chicken last night. We went to IKEA/HELL and the restaraunt was shut so we ended up at (curses) Burger King. My breath smelt really eggy the next day. I guess the sulphur dioxide additive was adding to my odours. YUK!
Give a man a fire and he is warm for a day, set a man on fire and he is warm for the rest of his life.