yeast and bacteria are present. As these microorganisms break down the fruit’s sugars, they can produce gases such as carbon dioxide.
As gas builds up inside the watermelon, it may mix with the fruit’s liquid and escape as foam or bubbling liquid through cracks in the flesh or rind. In other words, the watermelon may effectively become a small fermentation chamber.
A watermelon showing obvious signs of fermentation or spoilage should not be eaten. Some harmful bacteria can cause foodborne illness, and you cannot reliably determine whether a spoiled fruit
