Make A Difference (MAD) Market
Tomato / Kamatis
Ever wonder what is the greenish-yellow powder on the surface of your tomatoes?
An interesting characteristic of this substance is how hard it is to get it off your skin. You lather up with soap and water and the suds turn green. Rinse, and lather again, and the suds still turn green. You can wash your hands four or five times and the stuff just keeps coming off. It explains why all your towels and t-shirts get green stains in summer — no matter how many times you wash, there's still some left behind on your skin.
the green substance is a number of chemicals that are released from hairs situated on the surface of tomato leaves, stems and fruits - this stuff that gets all over your skin.
The little hairs that cover tomato leaves are technically known as secretory and glandular trichomes (SGTs). About one-third of all the vascular plant species have SGTs. They secrete various secondary metabolites -- that is, substances that aren't used for the growth or reproduction of the plant but have some other function.
SGTs contain the essential oils that give herbs their fragrance and flavor. In tomatoes, they produce acyl sugars, terpenoids, and flavonoids. Acyl sugars are lipids (fats) that are greasy to the touch, insoluble in water and soluble in alcohol. That's why they're so hard to wash off your skin. Terpenoids release the familiar tomato scent when you brush against the plant. Flavonoids are the substances in plants that are getting all the attention for their role in preventing cancer and cardiovascular disease.
These substances are thought to protect plants against environmental assaults including insect attacks, foliar diseases, extreme heat and excessive light. They are of great interest to plant breeders, who hope to use them to develop varieties resistant to late blight, early blight, Septoria leaf spot and other diseases. There is also some research into increasing insect resistance.
So now you know -the green stuff serves a very good purpose, from the point of view of the tomato plant. And that makes me more kindly disposed to the green stains on my towels and t-shirts in summer.
In other cases, different powders might be the result of plant fertilizers mixing with the above substance, or mixing with anti insect sprays. If your tomatoes are dirty, please let us know! :)