What you see: Darkened skin in a drip pattern around the stem of your mango
What it is: A chemical burn from the mango’s naturally occurring sap
Eat or toss: Eat! The mango flesh below should still be fine.
Cavalierly pull a mango off a tree and odds are good that the fruit will respond with an assault of its own—acidic white goo that shoots out of the stem.
That “latex,” also described as "sap," can irritate sensitive human skin. It can also damage the skin of the mango itself. That’s what happened to the mango pictured above.
The harsh latex chemically burned the mango, killing peel cells and causing them to discolor (not so different from how lots of fruit and vegetables turn brown when their cells are disrupted). The little dots you see are lenticels, or pores the mango uses to breathe, which darkened after contact with the harsh sap.
Mango growers follow special procedures to prevent “sap burn.” They typically harvest the fruit by trimming high up on the stem, far above where the fruit connects to the tree. They also take pains to wash off sap and initially store mangos stem-side-down so they can drain.
The initial burst of white-ish latex is known as "spurt sap" and can blast more than a foot in the air, University of Florida horticulture professor Jeff Brecht tells me. But once the harsh stuff has been released, its more innocuous cousin, "ooze sap," leaks out in a manner true to its name. For more on ooze sap, including a photo, and an explanation of why it's nothing to worry about if you see some on your store-bought mango, check out this previous EatOrToss post.
The streaky and smudgy sap burn trails are generally just skin-deep afflictions. And the “chemical weapons” in the spurt latex have been spent by the time the mango arrives at the store, so it’s fine to handle the discolored areas with your hands.
Jeffrey Brecht. Post-harvest plant physiologist. Professor of horticultural science. University of Florida.
Fresh produce facts: Mango. Postharvest Technology Center. University of California, Davis
Mango: Postharvest operations. Food and Agriculture Organization of the United Nations.
Mango Harvesting FAQs. Queensland Government. Department of Agriculture and Fisheries
Mango: Postharvest best management practices manual. Editor: Jeffrey K. Brecht. University of Florida Institute of Food and Agricultural Sciences. National Mango Board.
Attention all units: The mango sap should be considered armed and dangerous