Is that mold in this split-pit peach?
What you see: Your peach’s pit has split open, the area around the pit is bumpy and strange. You might be worried about mold.
What it is: The pit split while the peach was in the tree; the weird stuff around the pit is likely the peach’s efforts to repair the split.
Eat or toss: Eat! But be careful with that odd stuff by the pit, it’s unlikely to taste good and may have bits of broken pit in it. In some cases the split might also break the peach's skin. If you see unhealed, open wounds on the peach's exterior you should toss.
Ahhh, peach season, when we all look forward to sinking our teeth into perfectly soft and juicy….BRAINS?
The inside of this peach may appear to have creases and bumps akin to a frontal lobe, but fear not. This isn’t a secret attempt at making peaches sentient beings, nor is it what you’re more likely thinking: mold. You’re witnessing the unfortunate result of some missteps in this peach’s growth. This is a case of split pit.
Split pit occurs most often in peach varieties that are harvested early. (Different types of peaches ripen at different times of year; farmers switch between varieties to ensure you have a steady supply of the juicy stone fruits.)
The woody pit at the fruit’s center cracks open, prompted by factors including excess rain, temperature fluctuations, too much nitrogen in the soil, over thinning (when growers trim away some flowers or fruit to encourage the tree to make the remaining fruit bigger), and simply whether the peach is genetically more predisposed to the phenomenon. These factors lead the peach to grow faster than its cells can keep up with, which causes the split. This grow-so-fast-you-tear-yourself-apart issue is common in demogorgons and other horticulture crops; check out what can happen to tomatoes, potatoes, peppers and plums. In peaches with clingy pits, the fast-growing flesh literally grips the pit and and then pulls it in two.
Ok, but what about the “brains”?
The peach tried to repair the split pit by sending in undifferentiated cells, Catherine Belisle, a University of Florida PhD candidate, explained. Belisle, who has studied peach varieties in Georgia, said to think of “undifferentiated cells” as generic cells that haven’t yet gotten the order to turn into peach flesh, skin, pit or any other specific part of the fruit.
The undifferentiated cells might taste sweet, but they probably won’t taste like peach, Belisle said. Before eating such a peach, keep in mind:
The undifferentiated tissue will likely feel weird in your mouth and could have embedded shards of woody pit embedded. Fortunately, the healthy, surrounding tissue shouldn't be booby trapped.
Plenty of cases of split pit only affect the deep, internal workings of the peach, in which case the clean peach flesh is fine. But you should inspect the exterior of the peach carefully. If the peach's skin split open, which you'd most likely notice near the stem, bacteria and mold could have snuck in and you'll want to steer clear (more on why in this post about a cracked plum).
Back to that wrinkly "undifferentiated" stuff. It's called “callus” tissue. If you’ve ever seen white bits on a peach pit, you’ve seen a much less dramatic manifestation of such repair tissue. In that case too, you may fear it’s mold, but it’s actually the peach’s defenses on display.
“The crop is designed to protect itself and the way it does that is it forms this callus of undifferentiated cells,” Belisle said.
Clues from the outside
While you can’t always tell from the outside if a peach is afflicted with split pit, you can look for clues. First, check near the stem, where a severe pit split is most likely to break the skin. Second, according to experts at the University of California, the peach may be flattened on the bottom, while University of Missouri researchers note that split pit peaches are often larger and ripen faster.
The almond-looking thing inside the pit
If the pit has split entirely, you may see the almond-like kernel at its center. Called a “noyau” (French for "fruit stone"), the kernel inside stone fruit pits like peaches, apricots and cherries is famous for both its alluring fragrance, which chef and cookbook author Samin Nosrat describes in apricots as “the sweet smell of almonds, vanilla, apricots and lilies;” and its small, but unnerving dose of amygdalin, which the human body converts to cyanide. Nosrat writes that heat disables the poison, and the noyaux can be the quiet star of jams, infusions and other preparations. If you’re feeling bold, check out this Kitchn piece for tips on prepping it yourself
Catherine Belisle. PhD candidate. Postharvest horticultural sciences. University of Florida.
Lan-Yen Chang. PhD candidate. Postharvest horticultural sciences. University of Florida.
Noyau. The Oxford Companion to Food. Alan Davidson. p. 560.
Pits, pits, PITS!