To keep yourself and your family safe from food-borne illnesses, watch out for these signs of spoilage.

Who wants to eat spoiled zucchini, really? Or any other spoiled food, for that matter.

And yet, it can happen to any of us. You bring back the zucchini from the supermarket and just as you’re about to unpack the bags, you get a call from a good friend or remember that you forgot to buy this or that for dinner.

So you head off to do something else, and—by the time you get back—you’re wondering if the zucchini is still safe to eat or not. There’s also the case where you’ve kept the zucchini in the fridge or pantry a little too long and, now, you’re just not sure about their safety.

Can you cook them? Should you eat them? Or have they gone unsalvageably bad?

Food poisoning is nothing to scoff at, that’s for sure. One in five Americans suffers food poisoning each year (48 million, to be exact, according to the U.S. Centers for Disease Control and Prevention). On average, 128,000 people are hospitalized and 3,000 die from food-borne illnesses stateside alone.

Fresh vs. Spoiled Zucchini

To enjoy your food without second thoughts, you should know how to determine if the zucchini in your kitchen is spoiled before—not after—you and your household eat it.

A foul smell, dull and lifeless skin, and heavy wrinkling or excess mushiness of the fruit are tell-tale signs that zucchini has gone bad. In contrast, fresh zucchini have smooth, shiny skin—and they feel tender but still firm to the touch.

Inside, the vegetable should have a texture that can best be described as a buttery pumpkin, and, depending on the variety and time of year, its flesh should either be white, greenish, or slightly yellow.

Raw zucchini has a soft flavor that’s both slightly sweet and bitter. Cooking mellows out that flavor and brings out the natural aromas in the vegetable, particularly when it is fresh.

The smell and wrinkled, almost dead-looking skin are the most obvious signs that your zucchini is spoiled. Yet some of us choose to ignore these signs. The thing to know is that, as humans, we do not handle spoiled food well, whether it’s meat, dairy, or produce.

If you suspect your zucchini is spoiled and no longer edible, do yourself a favor and do not eat it. It’s not worth exposing yourself or others to the risk of food poisoning, even if you only get diarrhea and vomiting.

Why Do Zucchinis Sometimes Taste Get Bitter?

When zucchinis have a bitter taste, this is caused by a group of toxins called cucurbitacins. These toxins are common in wild zucchinis but have been found in commercially grown ones as well.

If you ingest too much of this toxin, you can experience toxic squash syndrome, which can cause nausea, diarrhea, vomiting, and even hair loss in extreme cases. If a zucchini or two are highly bitter in taste, err on the side of caution and throw them away.

How Long Do Zucchini Keep For?

Zucchini should still not be cooked and eaten if it is spoiled. Cooking spoiled food kills the disease-causing bacteria, no doubt about it, but all the toxins produced are still left in the fruit.

Uncooked zucchinis can be left out at room temperature for 3-4 days safely. After that, they are likely to start spoiling and should not be eaten. When you refrigerate them, they can last up to 1-2 weeks and, in the freezer, they will keep their best qualities for up to 3 months.

It should be noted that freezer burn on your zucchini does not mean that you need to throw it away. Instead, you can just cut off the parts that have been burned and resume as usual. The parts that have been freezer burned are okay to eat (it will not harm you), but will not have the same delicious taste or texture.

Cooked zucchinis can be left out at room temperature for 1-2 hours. After that, pathogenic bacteria may have grown to dangerous levels inside them, and, thus, they should be thrown away. Refrigerated, cooked zucchini, will be fine for consumption for up to 3-4 days.

Frozen cooked zucchini should also last well for around 3-4 months in the freezer. That being said, freezing cooked zucchini is rare; it’s one of those foods that are best enjoyed when eaten fresh.

In general, zucchini keep really well. They are hardy fruits that can be left out for several days when uncooked without a problem.

If you have a surplus of fresh zucchinis, it is a good idea to freeze them. You can do this by chopping them up or grating them. This way, they will be easier to thaw when the time comes, and it is less likely to get freezer burn. 

How Long Can Zucchinis Sit Out?

Raw zucchinis can be left out for up 4 days, making them a great choice if your refrigerator is full. If you have cooked zucchini that you want to refrigerate, remember to let it reach room temperature before storing it in the fridge.

The hotter it is, the shorter your zucchini’s life span will be. Anything that stays in the heat for too long will deteriorate very quickly, and zucchinis are no different.

You can estimate that, in summer, the safety time at room temperature will be cut in half.

So, if raw zucchinis are usually safe to be kept out in room temperatures for 4 days, it will be 2 days if it is really hot. Similarly, if you can usually keep cooked zucchini out for 2 hours on a regular day, on a hot day I wouldn’t want to push it past 1 hour. 

A Guide to Thawing Zucchini Safely 

You froze your zucchini, and now the time has come when you want to finally eat it. Great, but what is the best way to do that?

Thawing zucchini is really simple. You can put your frozen zucchini in a bowl of warm water to thaw it safely or place it in the refrigerator overnight.

If you have a microwave or are in a rush, put the zucchini in (make sure you are using a microwave-safe bowl), and put the microwave on half power. The time it takes to thaw properly varies depending on how much zucchini you are trying to defrost.

Does Zucchini Ever Spoil in the Freezer?

Even if you buy your zucchinis at a great discount and freeze them minutes later, they will not spoil while in the freezer. Food that is kept in the freezer will be kept indefinitely unless your freezer is malfunctioning.

For frozen zucchini to be unsafe, the zucchini will have had to have been spoiled already when you put them in the freezer.

They may have spoiled because of the way there were transported (gotten bruised), or stored in the wrong manner in the grocery store. If the fruit was damaged beforehand or went off, the best-by or sell-by date won’t mean anything.

It is possible—and not uncommon—for food to spoil before its printed date, and this is often a sign of poor handling and unsuitable storage or display conditions.

As long as your freezer works properly (it should be freezing your food to 0°F or lower), something else must have happened to the food. Besides, it is possible that the zucchini spoiled while it was thawing. If it was left out for too long, chances are that is a good reason for its discoloration and foul smell.