Any time the subject of fruit ripening comes up there are always at least a couple of emails about the evils of ethylene, which is the stuff that commercial fruit distributors sometimes use to “gas” fruits like tomatoes to ripen them before they get to the grocery store bins. I’m not saying I favor that practice (though in truth I don’t know what the alternative is, since ripe fruit would turn to mush after a few hours bouncing around in a truck) but the truth is there’s nothing harmful or “noxious” about ethylene gas. It is an entirely benign — dare I say natural — compound.
True, a lot of ethylene is produced artificially in petrochemical plants due to the worldwide demand, but generally speaking it’s fruits and vegetables that are the primary producers of ethylene gas. They use it as a hormone you see, which is to say a type of molecule that allows cells to “communicate” with each other. Ethylene is what “turns on” the fruit genes that I mentioned in the post just below, setting the stage for everything from color changes to sugar production to pectin breakdown.
The ancient Egyptians knew all about it. Maybe not the hormone, gene, gasses and enzyme bits, but they discovered that if they slashed sycamore figs as they grew, they ripened faster (damaged fruit emits a lot of ethylene). Likewise the ancient Chinese discovered that if they closed unripened fruit up in small rooms and burned particular kinds of incense, the same sort of quick ripening would occur.
What fruit produces the most ethylene? Why the banana. Maybe you use bananas to ripen your tomatoes. I sure do. All it takes is a couple of days with a banana in a paper bag to turn a green tomato red. A rock-hard avocado will soften overnight. Make sure when you’re looking for a good gas producer you pick a fairly ripe one. A brown banana is a virtual gas factory.
Oh, and is ethylene really “noxious”? If you mean that in the sense of being harmful, no. It’s natural and non-carcinogenic. Which is not to say it won’t do anything to you in a concentrated dose. Breathe enough in and it’ll put you to sleep, which is why ethylene is sometimes it’s used as a general anesthetic . Small doses have been found to stimulate the human pleasure response, which some scientists say is the reason we humans like to smell flowers (yes, flowers produce noxious gasses too).