Watermelons are a delicious and refreshing summer fruit. But like any fresh produce, watermelons do eventually go bad. Knowing how to tell if a watermelon is bad is important to avoid getting sick from eating spoiled watermelon.
This article will cover the signs of a fresh watermelon, what causes watermelons to go bad, how to tell if a whole or cut watermelon is spoiled, how long watermelons last, the best way to store them, whether moldy watermelons are safe to eat, and if you can get sick from eating bad watermelon.
Signs of a Fresh Watermelon
When selecting a fresh, ripe watermelon at the store or farmer’s market, look for the following characteristics:
- Color: The watermelon should have a vibrant, deep green rind with no blemishes or soft spots.
- Shape: It should be symmetrical and free from dents, cuts, or odd lumps.
- Size: Heavy for its size, feeling solid when lifted.
- Spot: There should be a creamy yellow/white spot on one side where it rested on the ground while ripening.
- Sound: Thumping it should produce a deep hollow sound, not a dull thud.
If the watermelon has these qualities, it is likely fresh and ready to eat! Once cut open, the flesh should be brightly colored, firm, and juicy.
What Causes Watermelons to Go Bad?
Watermelons can go bad for a few different reasons:
- Physical damage: Cuts, bruises, dents, or other physical imperfections allow bacteria and mold to take hold.
- Temperature: Heat causes watermelons to ferment and spoil faster. Cold temperatures can turn the flesh mushy.
- Time: Like other fresh produce, watermelons will eventually start to break down, dry out, and rot after a period of time.
- Contamination: Bacteria, yeasts, and molds can start growing if watermelon comes in contact with contaminated surfaces or utensils.
Proper storage and handling reduces the chances of watermelons going bad prematurely. But no matter what, they have a limited shelf life.
4 Signs of Spoiled Watermelon
Examine the watermelon’s exterior first. A fresh watermelon will have a smooth, firm rind with a cream or yellowish underbelly.
Soft spots or sunken areas on the rind can indicate the fruit is overripe or spoiled inside. Moldy growth or odd colors like blue, green or black mean the melon should be discarded.
Once cut open, a bad watermelon will show signs like:
- Brown or white flesh: Indicates rotten, fermented fruit.
- Mealy or dry texture: Water content has evaporated due to age.
- Off colors: Should be mostly red or pink, not orange or yellow.
- Mold growth: Can start off white but progress to black or green fuzzy mold.
A fresh watermelon has a light, sweet or floral smell. If you notice sour, fermented scents, or an “off” odor of any kind, that is not a good sign.
Rotten watermelons give off ammonia-like aromas. Trust your nose – if it smells funky, it’s safest not to eat it.
After examining its appearance and smell, taste a small piece of the flesh. Good watermelon tastes lightly sweet and has a juicy texture.
Bad watermelon will taste:
- Fermented or alcoholic
- Metallic or astringent
These flavors indicate spoilage. Rinse your mouth thoroughly if you taste odd flavors, to prevent any illness.
The interior flesh should be firm and juicy when freshly cut. Mushy, slimy or meal-like flesh means the melon is overripe.
Dry or grainy texture also indicates an older watermelon starting to spoil. The juices evaporate as it sits.
Brown or white moldy spots confirm the fruit has gone bad. Never eat moldy parts.
How to Store Watermelon?
Follow these tips to store watermelon correctly and enjoy it throughout the season.
The Shelf Life of Whole and Prepared Watermelon
How long watermelon lasts depends on whether it is whole or prepared:
|Whole watermelon at room temperature||2 weeks|
|Whole watermelon refrigerated||3-4 weeks|
|Cut watermelon refrigerated||5-7 days|
|Frozen watermelon||6-12 months|
Whole watermelons keep 1-2 weeks at room temperature. Refrigeration prolongs shelf life significantly. Prepared watermelon deteriorates rapidly, so freeze any you won’t use within 5-7 days.
Proper Storage for Whole and Cut Watermelon
- Store uncut, whole watermelons at room temperature for up to 2 weeks.
- For longer shelf life, refrigerate whole melons. They will last 3-4 weeks refrigerated.
- Keep away from ethylene gas producing fruits like apples and bananas, which speed ripening.
- Situate on a shelf or table, not on the floor where they can prematurely rot.
- Whole watermelons can sit out on the counter for short periods for convenience. But refrigerate after cutting.
- Refrigerate all cut watermelon within 2 hours of slicing to prevent microbial growth.
- Place cut melon in an airtight container or wrap tightly in plastic wrap before refrigerating. This prevents drying out.
- Use within 5-7 days for best quality and freshness.
- If cut watermelon has been left out over 2 hours, discard it. Do not refrigerate due to food safety risks.
Optimal Refrigerator Temperature
Chilling watermelon is key for longevity. For proper fridge storage:
- Set refrigerator temperature to 40°F or below. The colder the better for watermelon!
- Do not overload the fridge, as this reduces air circulation and cooling.
- Place watermelon in low humidity crisper drawers. High humidity causes sogginess.
Maintaining optimal refrigerator temperature and conditions keeps cut and whole watermelon fresh longer.
Using Freezer Storage to Extend Shelf Life
Freezing is a great way to enjoy watermelon out of season. Properly frozen watermelon lasts 6-12 months.
There are several freezing methods:
- Diced into cubes or balls
- Pureed or blended into juice
- Frozen into popsicles
- Left whole with rind on
Follow these steps to freeze watermelon:
- Wash watermelon thoroughly before cutting.
- Remove rind and seeds. Cut into desired size pieces or blend/puree.
- Arrange watermelon pieces in a single layer on a tray or sheet pan. Freeze until solid.
- Transfer frozen pieces to resealable airtight bags or containers, removing as much air as possible.
- Return frozen watermelon containers to freezer.
- For whole frozen watermelon, wash, dry, and freeze whole with rind on. Slice open to use.
Allow frozen watermelon to thaw in the refrigerator before serving or adding to smoothies and other recipes. Use within 24 hours after thawing for best quality.
Can You Eat a Spoiled Watermelon?
It is not recommended to eat watermelon showing signs of spoilage. Consuming spoiled fruit puts you at risk for foodborne illness.
- Salmonella – Causes fever, diarrhea, cramps, and nausea.
- Listeria – Causes fever, muscle aches, stiff neck, nausea. Can be fatal to the elderly, infants, or pregnant women.
- E. Coli – Causes bloody diarrhea, vomiting, and other issues.
Moldy, fermented, or rotten watermelon may contain hazardous bacteria. Discard the entire fruit if any part looks spoiled. Do not try to cut away just the bad sections.
With early stages of spoilage, sickness is unlikely but the fruit won’t taste good. Rinse your mouth if you taste fermented flavors.
What to Do With Bad Watermelon
A spoiled watermelon should not be eaten and should be disposed of carefully to avoid contaminating other foods. Here are some safe disposal methods:
- Throw away the entire melon, including any cut pieces. Place it in a sealed bag before putting it in your garbage can.
- Bury it deep in your garden or compost pile, if you have space away from food crops. This allows it to decompose underground.
- Blending spoiled melon in a garden blender makes “watermelon juice” you can dilute and pour at the base of garden plants as fertilizer.
- Sanitize any storage bins, cutting boards or tools that held bad melon by washing with hot soapy water, or using a disinfectant. This prevents transfer of bacteria.
Do not attempt to cook, freeze, can or otherwise “rescue” bad watermelon. The risk of foodborne illness remains. When in doubt, throw it out!
Can You Cut Away Bad Parts of Watermelon?
It is not recommended to salvage watermelon by cutting away visibly rotten or moldy sections. Bacteria are likely to have spread through the entire fruit, though not visible.
Mold and decay also produce mycotoxins that penetrate into the fruit. Mycotoxins can cause illness even from mold-free parts. It is impossible to know if the remaining fruit is safe.
For this reason, experts advise discarding the entire watermelon at first signs of spoilage. Trying to cut away just the obviously spoiled parts is unlikely to prevent foodborne disease. Prevention starts with learning how to identify bad melons.
How to Select Good Watermelons
Choosing fresh watermelons can help avoid finding a spoiled one later. Inspect watermelons carefully when buying and select only unspoiled fruits.
Here are tips for picking good watermelons:
- A heavy melon is more ripe and juicy than light ones. Lift to judge weight.
- Smooth, symmetrical shape without bruises or dents.
- Creamy yellow spot where melon rested on the ground. No white or green spots.
- Dry stem scar – should not show signs of mold or stickiness.
- Firm outer rind with no soft spots. Rind color irrelevant.
- Dull thump rather than hollow sound when tapped.
Avoid melons with any cracks, sunken spots or other flaws. Careful selection reduces the chance of winding up with a bad watermelon later on. Check fruits regularly while storing and refrigerate cut melons. Proper handling will help you catch spoilage early.
Frequently Asked Questions
1. Can you tell if a watermelon is bad by shaking it?
No, shaking a watermelon is not an accurate test of freshness. Whether it makes a sloshing sound or not doesn’t indicate spoilage. You can’t determine if a watermelon is bad or good from the outside alone. Cut it open and examine the flesh to truly know.
2. Why did my watermelon have a white foam inside?
White foam or fizzing inside a watermelon is due to fermentation. The natural sugars have been broken down by yeasts or bacteria, producing carbon dioxide gas and alcohol. This is an advanced stage of spoilage and the melon should be discarded.
3. Are black spots inside watermelon bad?
Yes, black spots or streaks in watermelon flesh indicate rotting. The black color is mold taking hold. Any watermelon showing dark internal mold should be thrown away. Don’t attempt to salvage parts without black spots, as toxins likely have spread.
4. My watermelon had a weird blue-green color inside. Is it safe?
Odd colors like green, blue or black in a watermelon’s flesh means it has gone bad. This is either mold or advanced bacterial spoilage. The fruit should not be eaten for food safety. Stick to pink or red internal color for fresh watermelon.
5. Can you eat a watermelon that smells funny but looks fine?
No, it is unsafe to eat a watermelon with an off or strange smell, even if no visible mold. Sour, fermented scents, or ammonia-like odor indicates microbes breaking down the fruit. An odd smell means toxins are present, so the melon should be discarded uneaten.
Identifying bad watermelon requires relying on multiple senses. Examine its appearance, aroma, taste and texture closely. Know the signs of mold, fermentation, dryness and other spoilage. Promptly throw away any questionable melons. This prevents foodborne illness, as harmful bacteria spread fast through watermelon’s moist flesh. With some basic checks, you can avoid an unpleasant encounter with a spoiled watermelon.