Freezing is one way that consumers can preserve foods and enjoy them at a later date. But not all foods are suitable to go in the freezer whether they'll deep in quality or pose potential health risks for those who consume them post-freeze.
Kevin Murphy, food safety and sanitation expert and professor and chair of hospitality services at the University of Central Florida's Rosen College of Hospitality Management, weighs in with his expert opinion on the topic.
Here are 10 foods you should avoid putting in the freezer.
It's no secret that liquids expand and contrast when placed in the freezer. For this reason, Murphy recommends avoiding placing glass containers full of liquids in the freezer. The same logic applies to cans and even plastic storage containers.
"The liquid can break or even explode in the freezing process," said Murphy. "This also goes for plastic containers that do not leave enough room for expansion of the liquid."
Although some say that it is OK to freeze eggs, Murphy said don't do it because the eggs may burst in the freezer.
"As things get cold, they contract. What happens to liquids as they contract and get cold - and as they reach the freezing point - they have this surge of expansion. Just as they hit the freezing point, they can explode," said Murphy.
"That's why you see when you put water in an ice tray, the cubes are bigger once they've frozen. That's what happens to anything that is constructed inside of a product like an egg."
When you buy lettuce from the grocery store or farmer's market, it is generally fresh and has a good crunch to it. The freezer breaks down the leafy green vegetable and causes it to lose its crispness, leaving you with a soggy salad.
"Lettuce will turn from crispy to mushy, limp, unusable green goop after it is placed in the freezer," said Murphy.
There are certain things you can refreeze, fruits and produce aren't one of them. Murphy said that sub-below temperatures are required to properly freeze fresh fruits and vegetables and that most home freezers aren't equipped to handle this process with a good end result.
"If you want frozen fruits and vegetable, then buy them that way. Manufacturers have the right equipment to properly freeze fruits and veggies," said Murphy.
Meats like sushi-grade tuna are previously frozen for 48 hours before it makes its way to the consumer, according to Murphy. He notes that many people think they are eating fresh tuna when they really are not. Murphy said that freezing meat that has already been frozen can result in poor quality and increases bacteria potential.
"Manufacturers usually freeze meat at 80 degrees below zero to help kill off any parasites. What happens during this rapid process is that, when the temperature cools and approaches freezing, the molecules within the meat don't get to explode," said Murphy. "When you refreeze the meat at a normal freezing temperature at home, usually about zero degrees, the meat becomes tough and does not taste good. You're also just inviting this change for microbial growth because they don't always die at freezer temperature."
Additionally, Murphy points out that refreezing meat causes the product to exude liquid all over the place. This happens when the meat is refrozen at a different temperature and the cells explode.
"You're freezing something that's already been frozen and you aren't freezing it properly at home. This causes product deterioration," he said. "My general rule of thumb is to leave freezing up to manufacturers."
Thinking about freezing those leftover wings and fries? Not so fast, cautions Murphy. The cold temperatures from the freezer will cause the fried foods to break down and lose their delicious crunch.
"For obvious reasons, freezing fried food causes the item to lose its crispiness. Also, frozen foods that have previously been fried do not reheat well," said Murphy.
According to the International Milk Genomics Consortium, milk can be frozen for one to three months. Although, as Murphy points out, the milk or other dairy product likely won't be the same as it was before freezing.
"Once these dairy products are later defrosted, they will separate into water and curdled chunks," said Murphy.
Murphy said that raw potatoes do not freeze well. If freezing a soup, stew, stew or other dish containing potatoes, its best to leave the potatoes raw and cook them when you are ready to eat the dish. The other option is to add the potatoes into the dish after it's thawed out.
"In a raw potato, the water and starch don't freeze well so you just get a mealy, grainy, bad tasting mess," said Murphy.
Although adding ice to your coffee isn't an issue, putting the coffee beans or ground beans in the freezer isn't the best idea.
"If you freeze coffee, you will end up with smelly and damp grounds that don't taste good because they absorb flavors and moisture from other products in the freezer or fridge."
Murphy is quick to points out that cells expand as they freeze and that causes the herbs to break down. When herbs are placed in the freezer, they will not come out looking like they did before.
"When you freeze herbs at regular freezing temperatures, which is about zero degrees if you have a good freezer, you've got this contraction, contraction, contraction. At that last moment when it actually freezes, the cells explode," said Murphy. "The herbs stay frozen, but when you defrost it you get this limp mush. The more tender herbs like parsley, basil, and cilantro are going to turn to mush. Some of the really hearty herbs that grow thick, like rosemary and thyme, maybe a little better off."
Also from Business Insider South Africa: