Should I eat it: unintentionally fermented watermelon edition

June 2, 2020 9:15 AM

I accidentally fermented a container of watermelon chunks by missing it when unloading groceries from the car. It tastes fizzy and tart, not spoiled. Is it okay to eat?

I went grocery shopping on Sunday and somehow missed unloading a sealed container of watermelon slices from my hatchback. I took it out today and tried one, and it has fermented. It tastes good, a little tart and fizzy. I want to make a drink out of it or something.

I like fermented things in general and am minimally risk-averse about food, but is there any concern about consuming store-bought watermelon chunks that fermented by accident in my car? Bonus question, would it be a bad idea for my five-year-old to try it, for science?

posted by centrifugal to Food & Drink (9 answers total)

Best answer: Normally when you ferment something, you either add preservative ingredients known to help minimize the growth of bad bacteria and yeasts, or you inoculate it with a pretty large dose of the yeasts and/or bacteria you want, trusting that they will grow the fastest and out compete any bad bacteria that also got in. You also generally are pretty careful with keeping the containers and implements sanitized so as to not introduce bad guys.

Since your watermelon was fermented without either of these steps, and packed in an environment where they assumed it would be refrigerated, it's an uncontrolled ferment, which means there's a chance it could give you food poisoning.

This sounds like an argument against, but it really isn't, I'm just telling you the risks. You're relying a bit on wherever cut up your watermelon to not have introduced any bad bacteria in.

I say "eat it if you want, don't feed it to anyone else" as a general rule for ALL "can I eat this?" questions!
posted by euphoria066 at 9:29 AM on June 2, 2020 [6 favorites]

Best answer: Won't venture about an adult stomach. But I am quite sure it's not a good plan for the 5 year old. (Looking at it and smelling it could be a science moment though -- nice idea.)
posted by nantucket at 9:36 AM on June 2, 2020 [2 favorites]

Best answer: I think one way that this is different from a home fermentation project is that the watermelon was sliced in a store. Pre-cut fruit & veg have been sources of outbreaks of stuff like salmonella and listeria. I'm pretty non-risk-averse about this stuff and have a cast iron stomach but I would not eat that watermelon.
posted by quaking fajita at 9:47 AM on June 2, 2020 [10 favorites]

Best answer: Fizzy and tart can equal a really terrible night a few days from now. Ask me how I know.

I definitely would not eat this watermelon.
posted by peanut_mcgillicuty at 10:12 AM on June 2, 2020 [4 favorites]

Response by poster: Ok, ok, thanks for being my food safety superego, Metafilter. I’ll toss this and figure out how to do the same thing but safely and on purpose.
posted by centrifugal at 10:22 AM on June 2, 2020 [1 favorite]

Good god, no. Directly in the bin. Pre-cut and improperly stored fruit is an extremely common avenue for food poisoning. This is the main reason you don't eat fruit in certain foreign countries if you can't see it being peeled. (Ask me how I know!)
posted by gnutron at 11:21 AM on June 2, 2020 [5 favorites]

Toss it somewhere you won't be able to smell it. If you have a nearby green bin, the rancid vinegar scent of spoiled watermelon will be gorge-rising in 24 hours.
posted by scruss at 12:00 PM on June 2, 2020 [1 favorite]

Here's a fermented watermelon recipe (basis for a Watermelon Basil Fermentini).
posted by Iris Gambol at 2:31 PM on June 2, 2020 [2 favorites]

The way to answer these questions is always to ask yourself, “Self, is this food item so delicious/rare/irreplaceable that I’ll still be glad I ate it 12 hours into a bout of debilitating gastrointestinal distress?”
posted by jesourie at 3:50 PM on June 2, 2020 [5 favorites]