How to freeze leftovers

Batch cooking and freezing leftovers are great ways to save food, time, and money. But done incorrectly, freezing is a great way to turn your tasty weeknight dinner into a freezer burnt, grainy mess. Read on for tips about what to freeze, how to freeze, and how to safely thaw and cook frozen food!

According to Canada's safe food storage guidelines, the following foods should not be frozen:

• Canned ham
  
  
• Deli or homemade salads
  
  
• Eggs fresh in the shell, and egg substitutes that have been opened
  
  
• Opened dairy products like yogurt, cottage cheese, or butter
  
  
• Lettuce

Other foods, handled properly, are safe to freeze but unpleasant to eat after they’re thawed. Avoid freezing;

• Creamy sauces and dips
  
  The milk fats in dairy products often separate from the liquid when they’re frozen, which can result in a curdled or grainy texture. This isn’t always noticeable if dairy is just one ingredient in a recipe- baked mac n’ cheese or lasagna is usually ok- but something like a creamy pasta sauce or cream cheese dip generally comes out badly.
  
  
• Fried food
  
  Fried food can be frozen and then thawed and reheated until it’s hot again, but it loses its tasty crispiness. If you’d like to freeze fried food, like chicken fingers or potato latkes, it’s better to assemble and freeze them uncooked, and fry them after they're thawed.
  
  
• Salads featuring raw veggies with a high water content
  
  When raw cucumbers, tomatoes, cabbage and herbs go in the freezer, the water in them freezes and expands into ice crystals. This damages the structure of the veggies, and they’ll turn into mush after they’re thawed.
  
  
•  Some egg-y dishes
  
  Cooked egg dishes (like quiche and breakfast casserole) freeze fine. Hard and soft boiled eggs freeze badly, and so do custards and meringues. Mayonnaise also develops an unpleasant texture in the freezer, so you’ll want to avoid freezing salads or dips that use a lot of it.
  
  
• Anything that is about to go bad in your fridge
  
  Food that’s unappealing because it’s past its prime is still going to be unappealing after a month in the freezer. It can be tempting to freeze the last bit of a big pot of chili that you’re sick of eating, but it’s better not to. Freezing food doesn’t actually kill bacteria and other microbes in your food that cause sickness, it just renders them inactive for the period that the food is frozen. When the food is thawed, they become active again. 

 

Most other dishes can freeze well, if stored correctly. Some popular freezer favorites include;

• Cooked ingredients like grains, beans, meat, veggies, and soup stock
  
  These all do well in the freezer, and are great to speed up meal prep.
  
  
• Grab n’ go convenience food
  
  Freezer aisle favorites like homemade burritos, breakfast sandwiches, quesadillas, and calzones are all pretty easy to make at home. They can be a lifesaver on days when you need something that can be eaten on the run. 
  
  
• Cooked saucy dishes like casseroles, pasta, soups and stews
  
  In these dishes, the more fragile ingredients are covered in a liquid that protects them from drying out. One caveat; pasta frozen in sauce, and rice or potatoes frozen in soup, may absorb too much liquid during the reheating process and get mushy. To avoid this, it’s best to slightly undercook pasta that you’re going to freeze, and hold off on cooking and adding rice or potatoes to soup until right before you serve it
  
  
• Baked goods and dough
  
  Most breads and pastries freeze really well (with the exception of custard fillings and egg white icing). If you’re a baker yourself, you can also freeze cookie dough, pie crust, bread dough or pizza dough.

1. Cool food completely before freezing

It’s difficult to wrestle hot food into storage containers, and putting it in the freezer can raise the temperature to an unsafe degree. Instead, allow food to cool slightly at room temperature (for no more than 30 minutes), then cover it loosely and put it in the fridge. Once it’s reached fridge temperature, it’s ready to be frozen

2. Transfer into storage containers

Considerations for choosing containers:

• Frozen food should only be thawed and reheated once, so choose containers that allow you to freeze food in portion sizes that can be eaten in one sitting
  
  
• Air exposure causes freezer burn on frozen food, so choose containers that are as airtight as possible.
  
  
• Take into account the amount of space in your freeze, and choose the most space efficient container available.

Common types of containers, and tips for using them:

• Freezer bags
  
  -Freezer bags are popular because they can be frozen flat and stacked. This saves space and speeds up thawing time.
  
  -Make sure to buy “freezer” bags, not “storage bags”; freezer bags are thicker, and will keep food fresh for longer. Alternatively, invest in some reusable silicone bags.
  
  -To fill a freezer bag with a liquid, place the bag inside a small pitcher or wide-mouthed measuring cup. Fold the mouth of the bag over the sides of the pitcher so that it’s held open. You can then easily scoop or pour liquid into the bag, and seal it shut. Place on a baking tray in the freezer to freeze flat; once frozen, they can be stacked on top of one another.
  
  -Whether you’re freezing something liquid or solid, squash as much air as possible out of your bag before sealing it.
  
  
• Rigid plastic and glass containers
  
  -Regular glass is likely to break at freezer temperature, so you’ll want to invest in tempered glass that’s marked “freezer safe”. Tempered glass is more expensive than reusing condiment jars, but it can often be put into the oven to reheat food.
  
  -Regular plastic storage containers are generally fine in the freezer, provided the lids seal air tight. You can reuse plastic yogurt or sour cream cartons, but the lids do not seal well, so you’ll want to wrap them in an extra layer of plastic wrap or foil. Plastic take-out containers often get brittle and shatter easily, so don’t reuse them in the freezer.
  
  -Water expands as it freezes, so leave a little extra room in your container if you’re freezing something liquidy- you don’t want your container to burst!
  
  
• Aluminum foil
  
  -Aluminum foil can be used instead of plastic to cover dishes or wrap up finger foods like freezer burritos. Just be sure to buy heavy duty foil that’s made to go in the freezer.
  
  -Lidded foil pans also can be frozen, if you’d like to prep a casserole or pasta bake that can go directly into the oven later.
  
  -Casseroles can also be frozen and then wrapped in aluminum foil only, if you’d like to retrieve your baking dish. Simply line the pan with parchment paper, make your casserole, and then freeze it. Use the parchment paper to lift the frozen casserole out of the pan, wrap it tightly in heavy-duty aluminum foil, and return it to the freezer. When you’d like to eat the casserole, just place it back in the pan to thaw and be reheated.

Whatever container you use, be sure to label it with permanent marker or freezer tape. You’ll want to know the name of the food, and the date it was packaged. You can include reheating instructions if needed too.

Food should be frozen at -18C, which is 0F or lower. You'll want to check your freezer to make sure that it's holding food at a safe termperature. Food frozen at a safe temperature is technically always safe to eat, but the quality declines over time. A general rule of thumb is that frozen food should be eaten within months, to be as tasty as possible. Canada's safe food storage guidelines have provided a detailed chart, which you can check out for more specific instrucitons.

Some kinds of food can be cooked or reheated directly from the freezer, though it will take more time than cooking them fresh. Can check your recipe for more instructions.

More often, frozen food is thawed before cooking or reheating it. Shelf stable food, like baked goods, can be left out to thaw on the counter. You never want to leave perishable food, or food that usually has to be refridgerated, to thaw at room temperature; this gives bacteria too much time to multiply and produce toxins that won't cook out in the food when it's reheated. Instead, follow one of the three methods below:

• Thaw in the fridge
  
  Frozen food is safest when thawed in the fridge, though this takes a while. Small portions of food may thaw overnight, while packages up to 5 pounds will usually thaw within 24 hours. Consider putting packages that may leak on a plate or pan to reduce mess. Because the food is never heated to an unsafe temperature, it does not have to be eaten immediately.
  
  
• Thaw in cold water
  
  If you didn’t take your food out of the freezer in time, you can place it in a sealed bag, cover the bag in cold water, and change the water every 30 minutes to thaw it more quickly. Never use warm or hot water; this raises the external temperature of the food to an unsafe degree, while the inside remains frozen. Food thawed in this way needs to be reheated and eaten right away.
  
  
• Thaw in the microwave
  
  Different models of microwave work differently, but they all should have “defrost” settings that you can use to rapidly thaw food. If need be, transfer your food to a microwave-safe container before defrosting; if you’re using freezer bags, check the packaging or manufacturer website to see if the product is microwave friendly. Food that’s been thawed in the microwave should also be cooked or reheated and eaten immediately.

 

Further reading

UGA Extension: Freezing prepared foods

MSU Extension: Choosing containers for freezeing food

K-State Extension: Freezing baked goods

 

Food is Too Expensive! was funded by the City of Saskatoon through our Healthy Yards partnership, the Cyril Capling Trust Fund of the College of Agriculture and Bioresources, and the Department of Plant Sciences. Focus group research to inform this work was collected by CHEP. Thank you all for helping us make healthy food more accessible!