Pascalization is a method of preserving food where it's submitted to intense pressure, inactivating yeast, mold, and bacteria but leaving the fruit untouched. The produce is submitted to 40,000-80,000 pounds of pressure per square inch for about 15 minutes, applied evenly from all sides. While the method isn't much used today due to the high cost associated with production, it turns out there might be a surprise benefit to preserving produce this way — it massively boosts the antioxidant count in fruits.
Research presented at a meeting of the American Chemical Society shows that fruit subjected to high hydrostatic pressure (the official name of Pascalization) saw an increase in extractable carotenoids of up to 500%. They tested mango, avocado and papaya, and while the latter two saw significant increases, the mango remained oddly untouched.
The researchers aren't sure why there are more antioxidants after preserving, but they think the fruit may be producing more as a defense mechanism after the stress of all that pressure.