Yellow indicator in tomatoes?
 

This morning, I spent a fair amount of time clearing out excess growth of
tomatoes in my little greenhouse. When I washed my hands, they turned very
yellow. That had happened before but I did not know what the cause was. I
thought that I had contacted nitrates from my nutrient solution and that it
had somehow caused the yellow color the same way that exposure to nitrate
does. I presumed that the alkaline soap was the proximate cause for turning
a leuco compound yellow.

This time, after washing away the color, I went back out and handled the
tomato plants some more. Hand washing brought out the yellow color again.

Is this typical of tomatoes? What is the substance involved?

Bill

Repeating Rifle wrote:

This morning, I spent a fair amount of time clearing out excess growth of
tomatoes in my little greenhouse. When I washed my hands, they turned very
yellow. That had happened before but I did not know what the cause was. I
thought that I had contacted nitrates from my nutrient solution and that it
had somehow caused the yellow color the same way that exposure to nitrate
does. I presumed that the alkaline soap was the proximate cause for turning
a leuco compound yellow.

This time, after washing away the color, I went back out and handled the
tomato plants some more. Hand washing brought out the yellow color again.

Is this typical of tomatoes? What is the substance involved?

Sounds like lycopene from the tomatoes or another carotenoid from the
foliage. Mild oxidation will then remove the color (benzoyl peroxide
acne cream; Oxy-Clean, dilute bleach), as will electrophiles (skunk
juice). Why don't you wear gloves?

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

On 7/29/05 11:34 AM, in article , "Uncle Al"
wrote:

Sounds like lycopene from the tomatoes or another carotenoid from the
foliage. Mild oxidation will then remove the color (benzoyl peroxide
acne cream; Oxy-Clean, dilute bleach), as will electrophiles (skunk
juice). Why don't you wear gloves?

It could come from the foliage. That was all I handled for my second test.

It is not a skin problem yet. It washes off easily. Nevertheless,
considering that only a small amount could have been carried on my hands, it
has all the earmarks of a strongly absorbing indicator dye.

I was just curious as to what might be happening. It might be the basis for
a good kitchen science experiment in these days of limited access to
equipment and chemicals.

Bill

Uncle Al wrote:
Repeating Rifle wrote:

This morning, I spent a fair amount of time clearing out excess growth of
tomatoes in my little greenhouse. When I washed my hands, they turned very
yellow. That had happened before but I did not know what the cause was. I
thought that I had contacted nitrates from my nutrient solution and that it
had somehow caused the yellow color the same way that exposure to nitrate
does. I presumed that the alkaline soap was the proximate cause for turning
a leuco compound yellow.

This time, after washing away the color, I went back out and handled the
tomato plants some more. Hand washing brought out the yellow color again.

Is this typical of tomatoes? What is the substance involved?

Sounds like lycopene from the tomatoes or another carotenoid from the
foliage. Mild oxidation will then remove the color (benzoyl peroxide
acne cream; Oxy-Clean, dilute bleach), as will electrophiles (skunk
juice). Why don't you wear gloves?

Not necessary unless you are sensitised. The neutral/acid form is
colourless and the alkaline soap form is very water soluble and an
interesting shade of yellow not dissimilar to fluorosene in colour but
without the obvious UV glow. Vegetable acid/base indicator dye.

The smell is also distinctive and I suspect it is a quite bit more toxic
than the fruit - solanaceae are not to be messed with. You can eat
tomatoes and potatoes but the rest of the plant is a really bad idea.
And related species include some extremely toxic plants.

Regards,
Martin Brown

On 7/29/05 12:13 PM, in article , "Martin
Brown" wrote:

Sounds like lycopene from the tomatoes or another carotenoid from the
foliage. Mild oxidation will then remove the color (benzoyl peroxide
acne cream; Oxy-Clean, dilute bleach), as will electrophiles (skunk
juice). Why don't you wear gloves?

Not necessary unless you are sensitised. The neutral/acid form is
colourless and the alkaline soap form is very water soluble and an
interesting shade of yellow not dissimilar to fluorosene in colour but
without the obvious UV glow. Vegetable acid/base indicator dye.

The smell is also distinctive and I suspect it is a quite bit more toxic
than the fruit - solanaceae are not to be messed with. You can eat
tomatoes and potatoes but the rest of the plant is a really bad idea.
And related species include some extremely toxic plants.

I have some more experimental data.

Certainly, my hands do have that tomato plant like smell after handling.

This last time, I did more foliage removal and staking. I washed my hands
and got the same yellow color from using soap. I again got a sink full of
yellow water. This time, I took a flake of potassium hydroxide and added to
the sink. The color of the sink water became much deeper. So, does that
describe solanin well enough to make solanin the likely candidate?

Bill

Don't know what it is, but this always happens from handling tomato
foliage. It's not just you, or your soap.

The tomato plants are trying to protect themselves by the smell and the color on your hands. You will have the yellow substance every time you handle the plants because it does come from the stems and leaves. If you are sensitive you can feel the stuff getting on you.

"Repeating Rifle" schrieb im Newsbeitrag
...
This morning, I spent a fair amount of time clearing out excess growth of
tomatoes in my little greenhouse. When I washed my hands, they turned very
yellow. That had happened before but I did not know what the cause was. I
thought that I had contacted nitrates from my nutrient solution and that
it
had somehow caused the yellow color the same way that exposure to nitrate
does. I presumed that the alkaline soap was the proximate cause for
turning
a leuco compound yellow.

This time, after washing away the color, I went back out and handled the
tomato plants some more. Hand washing brought out the yellow color again.

Is this typical of tomatoes? What is the substance involved?


I'll bet on lycopene as well.

And will I bet on picric acid if you grew them in abadoned ammunition
dump.

Repeating Rifle writes:
This time, after washing away the color, I went back out and handled the
tomato plants some more. Hand washing brought out the yellow color again.

Is this typical of tomatoes? What is the substance involved?

Nature frequently provides its own "antidote". Squash a rotten (i.e.,
waste overripe) tomato and lather your hands thoroughly with the mess.
The yellow stain comes off your hands then without the need for much soap
when you rinse.

I seem to recall nature providing an antidote for mulberry stain, and
for stinging nettles, too. I think you squash some of the red fruit (i.e.,
the unripe ones) to remove from your hands the stain that the black
mulberries cause.
--
John Savage (my news address is not valid for email)

On 8/2/05 5:19 PM, in article
, "muha"
wrote:

And will I bet on picric acid if you grew them in abadoned ammunition
dump.


How can picric acid be acid when you add alkali to it? :=)

Bill

"John Savage" wrote in message
I seem to recall nature providing an antidote for mulberry stain, and
for stinging nettles, too. I think you squash some of the red fruit (i.e.,
the unripe ones) to remove from your hands the stain that the black
mulberries cause.
--
John Savage (my news address is not valid for email)

I lived in Scotland for a period of time, and the locals quickly advised me
about
stinging nettles...Crushed dock takes the pain away quickly, and it seems
that dock
is almost found in the vicinity of nettles. Intelligent design? If it
works, use it.

Never got around to eating any steamed nettles, but heard they are quite
okay.

wrote:

"John Savage" wrote in message

I seem to recall nature providing an antidote for mulberry stain, and
for stinging nettles, too. I think you squash some of the red fruit (i.e.,
the unripe ones) to remove from your hands the stain that the black
mulberries cause.
--
John Savage (my news address is not valid for email)


I lived in Scotland for a period of time, and the locals quickly advised me
about
stinging nettles...Crushed dock takes the pain away quickly, and it seems
that dock
is almost found in the vicinity of nettles. Intelligent design? If it
works, use it.

No. Both plants happen to like heavy nitrogen rich soils.

Never got around to eating any steamed nettles, but heard they are quite
okay.

Cornish Yarg cheese is wrapped in nettle leaves. Very good it is too!

http://www.teddingtoncheese.co.uk/acatalog/de255.htm

Regards,
Martin Brown

On 8/3/05 5:04 AM, in article
, "
wrote:

I lived in Scotland for a period of time, and the locals quickly advised me
about
stinging nettles...Crushed dock takes the pain away quickly, and it seems
that dock
is almost found in the vicinity of nettles. Intelligent design? If it
works, use it.

For those of us not raised in the UK, please tell us a bit more about dock.
I have had the opportunity to meet what I think is stinging nettle. Are Us
nettles pretty much like European ones?

Speaking of intelligent design, I have been in places with soft pine needles
or the like where you lie down to recover if hit with a rock that was
nearby.

Bill