Except for ice cream and popsicles, foods kept in the freezer are typically heated before consumption. Frozen dishes or homemade leftovers likely end up in the microwave, oven, or on the stovetop, often for safety, aside from taste.
Heating frozen foods is logical, especially if they contain raw ingredients that require cooking. Many frozen foods are uncooked initially, which is why their packages provide specific heating instructions. Nobody wants to experience food poisoning symptoms like vomiting or diarrhea after a meal.
However, there’s an exception to the always-reheat rule: frozen vegetables. Whether boxed or bagged, not all frozen vegetables need to be cooked. Some can be enjoyed raw if you follow guidelines to determine which ones are safe to thaw and eat.
First, consider the type of vegetable frozen. If you would consume it fresh, you can likely eat it once thawed. For example, peas, carrots, and green beans frozen immediately after harvesting without additional ingredients can be simply thawed. You can eat them as they are or add them to salads or other uncooked dishes.
Safe to eat fresh, usually safe to eat frozen
The ability to consume some vegetables after freezing is due to a process called flash freezing. This involves freezing them right after washing and slightly heating them for a few minutes (a technique known as blanching). Washing removes debris, and blanching eliminates lingering bacteria.
Cardiologist Dr. Stephen Kopecky explains (via Mayo Clinic) that consuming thawed vegetables that were flash-frozen might be healthier than eating their fresh counterparts after a few days on grocery shelves or in the fridge. “We know once it’s picked a few weeks ago, it starts to decay,” says Kopecky. “[S]tudies have shown if you can flash-freeze something, it will retain its nutrients better because it retains its cellular integrity so the cells don’t get deformed.”
Maximize nutrient retention by freezing vegetables you can’t consume immediately. For instance, if your garden overflows with freezable veggies, consider washing, blanching, and freezing them in suitable containers for later raw consumption. Just be aware that not all vegetables freeze well, such as lettuce, cabbage, cucumbers, and celery. Conversely, many vegetables with low water content, like corn, broccoli, and squash, freeze and taste well.
Extra ingredients may mean extra heating steps are required
Before thawing and eating all the frozen vegetables in your kitchen, remember that some need cooking first. If a dish includes vegetables and raw chicken, freezing doesn’t eliminate chicken bacteria; it remains. As food safety expert Trevor Suslow notes (via NPR), freezing bacteria prolongs its activity. “It [freezing] actually does a pretty good job of preserving many of the pathogens and microbes that will cause problems later if thawed out.”
For reheating vegetable-based meals that shouldn’t be consumed raw, consider using a traditional oven. Food science specialist Martin Wiedmann explains (via NPR) that “with a frozen ready-to-cook food, I would always go with the stove, not the microwave,” since microwaves may not heat evenly, leaving some foods below 165 degrees Fahrenheit (the temperature that kills harmful bacteria) even if the plate feels hot.
