Heat and poor storage conditions can speed up deterioration.
A watermelon that has been stored too warm for too long may develop unusual texture, internal breakdown, or fermentation.
What About the Claim That Chemicals Cause the Cracks?
Some viral posts blame a plant-growth regulator called forchlorfenuron, also known as CPPU.
This substance is used in some agricultural applications to influence fruit growth. However, seeing cracks inside a watermelon does not prove that the fruit was treated with this chemical.
Natural hollow heart and other growing conditions can produce very similar appearances.
So you cannot diagnose chemical treatment simply by looking at a cracked watermelon.
When a Cracked Watermelon Is Probably Fine
A watermelon with internal cracks may still be edible when:
The flesh is firm
The color looks normal
It smells fresh and sweet
There is no foam
There is no sliminess
There is no sour or alcoholic smell
The rind was not damaged or punctured
Clean, crisp cavities are more consistent with a growth defect than active spoilage.
When You Should Throw It Away
Do not eat the watermelon if you notice clear signs of spoilage.
Foaming or Bubbling
Foam coming from the watermelon is a major warning sign.
Watermelon contains natural sugars, and yeast or bacteria can begin fermenting them. As microorganisms produce gas, pressure can build inside the fruit and cause bubbling or foaming liquid.
Sour or Alcohol-Like Odor
Fresh watermelon should smell mild and sweet.
A sour, fermented, or alcohol-like smell suggests that microorganisms have begun breaking down the fruit.
Slimy Flesh
Fresh watermelon should be crisp and juicy.
A slippery or slimy surface is a strong reason to discard it.
Extremely Mushy Texture
Softening can happen with overripeness, but flesh that is collapsing, watery, or unusually mushy may indicate spoilage.
Leaking or Swollen Rind
A watermelon that is leaking, unusually swollen, cracked externally, or under visible pressure should be handled cautiously and discarded.
Why Foaming Watermelon Can Be Dangerous
Fermentation itself can make the fruit unpleasant, but the bigger problem is that obvious spoilage means microorganisms have been growing inside it.
You cannot tell by appearance alone exactly which organisms are present.
That is why a watermelon that is bubbling, foaming, leaking, or smells fermented should be thrown away rather than tasted.
