Shallot, Allium cepa.(Photo by FlowerPhotos/Universal Images Group via Getty Images)
Food - Drink
What The Milky Substance Coming From Your Shallot Is
If you’ve ever sliced a shallot in half and seen a mysterious, white, milky liquid ooze out, don't hastily throw the shallot in the trash and rinse off your cutting board. This strange phenomenon may look unappealing, but is very common, occurs in other types of onions, and poses no problems for cooking and eating.
The liquid that comes out of a shallot is a mixture of water, hydrogen sulfide (the stuff that makes your eyes tear up), sulfuric acid, and sulfur dioxide. This liquid is less a sign of spoilage and more of an indication that the vegetable is close to the end of its post-harvest lifespan, meaning it's good that you're using it now.
However, if you observe a gel-like substance around your shallots, plus other signs of spoilage like mushiness, a yellow color, or a bad smell, you should throw them away. Store your shallots outside of the refrigerator, inspect them before cooking, and don't fret about a bit of juice if everything else looks fine.