The white fuzz inside your clementine is supposed to be there
What you see: A delicate white fluff in the center of your clementine (or tangerine, or other type of mandarin) What it is: Basically just an airier version of the white pith that lines the inside of the peel and the space between segments. It's called albedo. Eat or toss? The citrus is perfectly fine, so eat! Some people don’t eat the albedo itself because it can be bitter, but that’s a question of taste and not safety.
The story: For the paranoid among us, the delicate, fluffy white fibers at the center of some clementines can look hauntingly like the delicate fuzz we associate with mold.
Fortunately, however, this is not mold, but rather “albedo,” or, the white pith inside all citrus fruits. Albedo—you see it inside the peel and also in the “core” of the fruit, and in the threads you probably pick off your orange segments—is a loose network of cells containing relatively large air pockets. This makes sense when you consider that albedo is sort of like the fruit’s natural answer to packing foam. It cushions the citrus from falls and other fruity collisions.
While some citrus fruits have a tight connection down their central cores, mandarins (a category that includes this clementine) don’t. There’s an open space in the very center and sometimes you’ll find a particularly fluffy bit of albedo taking up residence.
Steve Futch, an extension agent at the University of Florida’s Citrus Research and Education Center, notes that different varieties of citrus simply have different albedo characteristics, which means that sometimes you get a clementine with a fluffy albedo interior, and other times the pith is more compact.
“They’ll actually even vary depending on how mature the fruit is,” he said. “Later in the season it gets fluffier than at other times of the year.”
Thanks to Caroline S., of Melbourne, Australia for submitting this question!