White stuff oozing out of your squash?

What you see: White stuff oozing out of cut squash when you microwave it; or clear, sticky stuff seeping out during peeling and chopping

What it is: Likely a sugar-based substance ferrying useful compounds throughout the squash

Eat or toss: Eat! This stuff won’t hurt you (though it can be hard to wash off your hands, clothes and household pets (don't ask)).

The story:

In my ongoing efforts to find the best, finger-safest way to peel and cut a butternut squash I tried lopping the top off and zapping in the microwave. The squash did soften up a little, as expected. Less expected: beads of white sticky stuff oozing out.

“It’s a sugar substance,” Penelope Perkins-Veazie, a horticulture professor at North Carolina State University, told me. Her lab once attempted to investigate the ooze's potential as an adhesive. “It’s perfectly safe,” she said. “It just looks horrible.”

If chopping a squash has ever left your hands a sticky mess, you probably encountered the same stuff, though it may have been clear and not white like the goo that oozed out of my squash. Perkins-Veazie said heating the squash may have caused the clear-to-white color change.

The globs mostly line up in a circle at the edge of the squash because that region of the squash simply houses more of the goop. The stuff was traveling through part of the squash’s phloem, or the tissue that transports nutrients throughout a plant. My microwave excited the water ferrying those nutrients and caused the sticky stuff to bubble up, as you see in the image.

When Perkins-Veazie’s lab studied the ooze's commercial adhesive potential several years ago, she concluded that it was sugar based, but also contained another substance she couldn’t quite pinpoint. Possibly some kind of protein. Research halted amid fears the goop would ruin expensive lab equipment.

Don’t worry about eating an oozing squash like this, Perkins-Veazie says, but do keep it away from your clothes.

“The protein may be why this residue is so hard to remove from counters and clothing (I've ruined a few pairs of jeans harvesting butternut),” she wrote in an email. “We found that we have to wipe down counters rapidly before the stuff dries. Dawn [dish soap] helps dissolve the dried on stuff, but we never did find the magic bullet to remove the dried on exudate from clothing.”


Penelope Perkins-Veazie. Horticulture professor. North Carolina State University.

Phloem. Britannica.

The Secret Phloem of Pumpkins. Robert Turgeon and Karl Oparka. PNAS July 27, 2010.

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