Becky Krystal, CiCi Williamson & April Umminger
THE WASHINGTON POST – These days, we’re all counting on our food supplies at home to last longer between reduced trips to the grocery store. Your freezer is an important part of that strategy. The freezer can preserve food indefinitely without the danger of spoilage – and keep it in peak condition until you’re ready to eat it. That can’t always be said for the pantry or refrigerator. But how well your food holds up on ice is largely dependent on your freezer savvy. Have you wrapped the food sufficiently? Did you freeze it quickly? Should it have been frozen at all? Is your freezer cold enough? We have insight on all those questions, and more, in this handy guide.
HOW FOOD FREEZES
When food is frozen, the water in its cells freezes and expands. Two methods are usually used.
In quick – or fast – freezing, the temperature of foods is lowered below zero degrees within 30 minutes.
FOR FASTER FREEZING
– Do not stack containers before freezing, but spread them in one layer on various shelves. Stack after the food is frozen.
– Freeze foods at zero degrees or lower. Optimally, it should take no more than two hours to freeze a two-inch-thick package of food.
– When adding a large number of foods to the freezer, set the temperature to the coldest setting several hours beforehand.
– Do not overload the freezer with unfrozen food, which slows the rate of freezing and may compromise quality. Add only the amount that will freeze within 24 hours, usually two or three pounds of food per cubic foot of storage space.
WHAT COULD GO WRONG
Freezing food cannot improve its quality. However, several factors can compromise good food that was frozen badly.
Growth is stopped when food is frozen, but microorganisms are not destroyed. When food is thawed, the microorganisms become active again and multiply; food must be cooked to be safe.
– Ice crystals
Formation of small ice crystals is better for food. Large ice crystals tend to rupture cells and may cause a texture change.
– Freezer temperature
The storage life of foods is shortened as temperature rises. A temperature of zero degrees or lower should be maintained to keep foods at top quality.
Fluctuating temperatures result in growth of ice crystals, further damaging cells and creating a mushier product.
Oxygen may cause flavour and colour changes if the food is improperly packaged. Many foods change colour when frozen, due to lack of oxygen or especially long storage. For example, red meat can turn brown; it is still safe to eat.
Freezing slows enzyme activity, and most food keeps when put in the freezer. In vegetables, however, enzymes must be inactivated before freezing.
To minimise the risk of freezer burn, caused by moisture loss, don’t thaw and refreeze food numerous times. That causes food to dry out faster. If food does suffer from freezer burn, cut off the affected areas – before or after cooking – and use the rest of the food.
If the power is off, food in a full freezer will usually stay safe for about two days with the door shut. A half-full freezer or the freezer compartment in a refrigerator will keep food safe for about 24 hours. When the power returns, food is safe if it is partially frozen, contains ice crystals or is “refrigerator cold” (40 degrees).
STEPS TO KEEP IN MIND
1. Preparation and packaging
Packaging materials must be moisture and vapour resistant, durable and leak proof to maintain the quality of food. Leave head space of half to one-and-a-half inches to allow for expansion. Label packages on the date food is frozen.
Do use: Plastic freezer containers, plastic freezer-weight bags, aluminium foil, foil pans, coated freezer paper, heavy plastic wrap, milk in plastic jugs, zip-top bags.
Do not use: Cottage cheese or yogurt containers, bread wrappers, produce bags, wax paper. These are generally not airtight or thick enough. Generally, freezing in glass jars is not recommended, as they can break, but if you decide to, make sure you leave enough room for expansion and confirm that the glass is tempered or freezer-safe.
2. Freezing points
Not all foods freeze alike. In fact, only foods with a high water content freeze at 32 degrees. Foods with a high protein, fat or sugar content require lower temperatures to freeze. Once frozen, all foods should be kept at 0 degrees or below to prevent moisture loss and preserve quality.
Most vegetables freeze fast at or just below 32 degrees.
Fish, meat and poultry don’t freeze until they reach around 26 degrees because they contain high amounts of protein and fat. (Wild salmon is 68 per cent water.) Tip: To help a package of ground meat thaw faster, create a deep indentation in the middle before freezing.
Foods with high sugar or butterfat content are harder to freeze. At three degrees, only about 75 per cent of the water in ice cream is frozen.
Textural changes are more noticeable in fruits and vegetables that have a higher water content, and foods that are eaten raw.
Changes from freezing are not as noticeable in food that is cooked later, because cooking also softens cell walls.
In the refrigerator (40 degrees or below): Slow but safe. Allow one day for every four pounds of whole poultry; one day for a one-pound package of meat, poultry or seafood; and two or more days for roasts, and steaks.
Safe to refreeze? Yes. Raw or cooked frozen food thawed in a refrigerator is safe to eat if refrozen.
In cold tap water: Faster than refrigerator thawing; must cook immediately after thawing. Submerge food in leakproof bags in a bowl of cold tap water. Allow about an hour per pound for small packages of food, 30 minutes per pound for whole poultry.