Wednesday, November 07, 2007

The Ultimate Guide to Freezing Food

The Ultimate Guide to Freezing Food

This two-part article looks at the many ways to freeze food (including specifics for common food types), as well as a few suggestions for getting the most out of your freezer itself. It can be a wonderful piece of equipment.

Chances are that when you buy a new refrigerator, the freezer just comes along for the ride. It's a part of the kitchen that most people don't spend much time thinking about.

It can be, however, an extremely efficient tool for putting aside excess food for later use. If you enjoy saving time when preparing your evening meal; being able to add fruit to your breakfast all through the year; or just love the idea of having home-made sorbet on hand whenever you like - read on.

Chest Freezer

The basics of freezing

No matter what type of food you're freezing, there are several basic guidelines that will make your life easier, and help you get the best results. These are :

  • Freezing can retain quality, but not increase it. Begin with good quality food.
  • Try to prevent air coming in contact with the food, and moisture from escaping. Both of these will dry things out, and can ' burn' them in many cases.
  • Freeze foods as quickly as possible. This will minimise the size of ice crystals that will form, limiting the damage to the food when thawed.
  • Foods should be slightly undercooked when frozen if they are to be reheated when thawed.
  • Only put as much food in the freezer as will freeze within the next 24 hours or so (usually about 2-3lb per cubic foot).
  • Rather than freezing spices, add them just prior to serving a meal. They can change colour and flavour when frozen.
  • Label things so you know when they were frozen, and when to take them out.

How to freeze vegetables

Most vegetables freeze quite well (they'll happily stay frozen for several months). Where possible, use the youngest and most tender of those available.

Here's what's involved :

Preparation

  1. Clean the vegetables to remove as much dirt as possible.
  2. Trim them, removing any unwanted stalks and leaves.
  3. Cut them into bite-size portions.

Blanching

Many vegetables contain a number of enzymes which cause them to lose their colour and flavour when frozen. Blanching (putting the vegetables briefly in boiling water) stops these enzymes from acting.

To blanch the vegetables, set up a pan of boiling water beside a bowl of ice water. Using a slotted spoon, put a small handful of vegetables into the boiling water for a couple of minutes*, then transfer it to the ice water (to stop it cooking). Pat it dry, and put it aside. Repeat with the rest.

* times vary, so here are the recommended blanching times for a number of common vegetables :

Vegetable Blanching time
Asparagus Wash, sort by size. Snap off tough ends. Blanch for 2-3 min.
Beans Wash. Trim ends. Cut if desired.Blanch for 2-3 min.
Beetroot Wash. Remove tops, leaving about an inch. Cook until tender (25–30 min for small beets; 45-50 for large ones). Cool promptly, peel, trim tap root and stem. Cut into slices or cubes. Pack into freezer containers.
Broccoli Wash. Trim leaves. Cut into pieces. Blanch for 3 min.
Brussels sprouts Wash. Remove outer leaves. Blanch for 4-5 min.
Cabbage Wash. Discard course outer leaves. If shredded, blanch for about 1.5 min. For wedges, blanch for 3-4 min.
Carrots Wash, peel and trim. Cut if desired. Blanch for 2 min (small carrots) - 5 min (large ones).
Cauliflower Discard leaves and stem, wash. Break into
flowerets or leave small heads whole. Add 1 tbsp vinegar to water, and blanch for 6 min.
Corn on the cob Remove husks and silks. Trim ends. Blanch medium-sized ears for 8 min. Wrap ears individually in plastic wrap or freezer bags.
Eggplant Wash, peel, slice 1/3 inch thick. Blanch for 4 min in water containing a tablespoon of citric acid or lemon juice.
Herbs Wash. Snip or leave on stalks. For basil only, blanch for a minute. For other herbs,
blanching is not necessary. Freeze in a single layer on trays or baking sheets.
Mushrooms Wipe with damp paper towel. Trim. May be frozen without blanching.

Once all the vegetables have been blanched and cooled, pack them straight into containers or bags. Alternatively, lay them out on baking sheets / trays and freeze them like this (put them into containers or bags later - they'll fit better, and can be easily broken up).

How long will they last?

Frozen vegetables will generally last for 3-6 months.

Cooking with frozen vegetables

Frozen vegetables can generally be cooked when still frozen (no defrosting required), although some leafy greens are easier to separate when thawed a little.

To boil them, use about 1/2 cup of water for every 2 cups of vegetables (the rest is already in the ice). Steaming and microwaving are also good options.

How to freeze fruit

When it comes to freezing fruit, different types are treated in different ways. Before we get into specifics, here are a few general guidelines :

  • Berries do well when frozen straight after harvesting. Apples, plums and peaches may need to wait a few days before hitting the freezer.
  • Small whole fruits (such as cherries) can be frozen on trays for later use in salads, drinks and garnishes.
  • Most fruits can be happily frozen for 8-12 months. Citrus fruits and juices should only be kept 4-6 months.

The general process for freezing fruit is to clean, trim and slice it; place it on trays or hard containers, and cover it with a mild syrup to prevent it from going brown. The specific steps for a number of common fruits are listed below, but first : the anti-browning syrup.

Preventing the fruit from going brown

If the fruit is likely to darken when frozen (see table below), simply cover the pieces with ascorbic acid or citrus juice (in the case of firm fruits, they can even be steamed). To do this :

Ascorbic acid : this can usually be purchased from pharmacies or supermarkets. If you're unable to find any, just crush up a couple of Vitamin C tablets and add a little water.

Citrus juice : although this isn't quite as effective as the ascorbic acid, it definitely helps. Add a few tablespoons of juice to a quart of cold water, and soak the fruit pieces in it for a minute or two. Afterwards, pat them dry, put them in the containers and cover them with sugar, syrup, water or fruit juice.

Packing

Prior to freezing, the fruit is 'packed' or placed into containers and covered with acid, syrup, water, fruit juice or sugar. This prevents the fruit from losing quality whilst frozen - when thawed it should be identical to a freshly picked piece.

Common methods of packing include :

Syrup pack : a 30% syrup (a third sugar, the rest water) is recommended for most fruits (very sour fruits may need a little more sugar). When the syrup is cold, pour about 1/2 cup into the container. Add the fruit, and then cover with the syrup. Make sure to leave a bit of space at the top of the container (it'll expand slightly).

Sugar pack : sprinkle a little sugar over the fruit, and mix gently with a large spoon. The sugar will help to draw the excess juice out of the fruit.

Once again, make sure there's a bit of room at the top of the container.

Unsweetened pack : use water (with ascorbic acid if necessary) to cover the fruit. Allow some headspace for expansion.

Tray pack : spread small, whole fruits out in single layers on trays or baking sheets. Once frozen, repack them into bags or containers and put back in the freezer.

As they're already frozen, there's no need to allow for expansion in the containers.

The process itself

Details of the process for common fruits are :

Fruit Preparation
Apples Wash, peel, core, and cut into pie slices. Cover with ascorbic acid.
Apricots, Peaches and Nectarines Wash in cold water and sort. Dip apricots or nectarines in boiling water until skins loosen, about 15 to 20 seconds. Chill, peel, halve and remove stones. Pack with syrup (above).
Bananas Peel and mash thoroughly. Add 1/2 teaspoon ascorbic acid or lemon juice per cup of mashed banana. Package, seal, and freeze.
Berries Wash and sort. Pack in syrup.
Cherries Wash, sort, stem, and pit. Pack in syrup; add ½ teaspoon ascorbic acid.
Citrus Fruit Wash, peel, section or slice fruit. Add ¼ teaspoon ascorbic acid to some sugar, and sprinkle over each layer. Let stand in refrigerator until fruit forms its own juice. Stir gently, and freeze.
Cranberries Wash, sort and pack without sugar.
Currants (use large varieties where possible) Wash in cold water and sort. Pack in sugar using 1 cup sugar to 8-9 cups fruit. For cooking, pack dry without sugar.
Gooseberries Wash and sort. Pack without sugar or syrup or mix berries and sugar called for in pie recipe.
Melons Wash. Cut flesh into ½- to ¾-inch cubes or balls. Cover with sugar syrup, using 2 cups sugar to 1 quart water. Serve partially frozen.
Pineapple Peel and core. Dice, slice or cut into wedges. Cover with syrup.
Rhubarb Remove leaves and woody ends, wash and cut in 1-inch lengths. Do not blanch. Pack with sugar.
Strawberries Wash, sort and stem. Pack whole, sliced, or crushed berries in a light syrup.
Tomatoes Cook completely (boil) prior to freezing.

How to freeze nuts

Most nuts (whether whole or chopped, shells or not) freeze quite well. To do this, simply double-bag them in freezer bags; and pop them in the freezer.

They'll keep for around 6 months.

Do the nuts need to be defrosted prior to use?

This varies according to the way you intend to use them. For dishes that are going to be heated in any case (such as stir fries ), using them frozen is fine.

If you're going to eat them as they are (say you're sprinkling them on ice-cream), thaw them a little first. They'll taste better.

How to freeze meats

Whilst the frozen vegetables, fruit and nuts are all great to have; for most people the core of their freezer use centres around meat. After all, this is where the big financial savings come in (more on that in part II).

Although freezing meat is a fairly straightforward process, there are a few things to keep in mind :

  • Freezing meat doesn't magically reverse spoiling. Make sure the meat is fresh to begin with.
  • If you've ever tried to separate a couple of pieces of frozen meat, you'll know just how frustrating it can be. If you're putting two or more pieces in the same bag or container, place a couple of sheets of freezer paper between them.
  • Game meats should be dressed and cleaned as soon as possible after shooting. There is no need to stuff them before freezing.
  • Label things with the date by which they should be used .

The general process

To freeze meat, simply :

  1. Trim fat and remove unnecessary bones
  2. Cut into meal-sized portions
  3. Place into freezer bags, plastic containers or wrap in foil or freezer paper (make sure to separate pieces with paper or foil)
  4. Place in the freezer for desired time (maximum storage times listed below)

Nice and simple.

How long will it last?

Meats vary a little; depending on type, whether they're cooked or not and the amount of liquid in them. Here are a few suggested times :

Type Time
Large cuts of meat (such as steaks) 6-12 months
Ground or minced meat 3 months
Cooked meats 1-2 months
Bacon and cured hams 1 month
Hotdogs, lunchmeats and shaved meats 1-2 weeks

NB : For meats bought at the supermarket, they're probably already packed in some form. Before freezing them, cut them to size (one piece per meal) and repack them. This will get rid of the excess gases and fluids which were present when purchased.

Freezing Seafood

Seafood can certainly be frozen, and fresh seafood freezes well. A few points to keep in mind :

  • Freeze the seafood as soon as possible after it's caught
  • Whole fish should be gutted and cleaned
  • Once frozen, take out of the freezer, dip in water and put back in (this forms a protective coating)
  • Smoked fish tastes slightly salty after freezing
  • Freeze small fish whole, and cut larger fish into steaks prior to freezing
  • All varieties of seafood can be frozen (for specifics, see the table below)

Freezing seafood other than fish

There are many, many varieties of seafood available - and several ways to freeze it. The following table lists the process for several common items.

Food Process
Lobster Cook in salted, boiling water for 8-10 min. Place in bags or containers, and cover with brine. Freeze.

To use, boil for another 8-10 minutes (from frozen).

Scallops Rinse well to remove sand and shell. Drain, place in bags or containers and cover with brine; freeze.
Clams and Mussels Rinse well. Steam until opened, and remove shells. Cover with brine and freeze.
Prawns The shells can be left on. Simply put them in containers, cover with water and pop them in the freezer.
Squid and Octopus Freezing actually tenderises the meat. Clean and gut them, place in an airtight bag and throw them in.
Oysters Rinse well. Shuck, cover with their own liquid and freeze.

NB : Oysters can also be frozen invidually (in their own liquid) in ice-cube trays.

How long does it last?

Most fish will last for a few months or more. Here's the breakdown :

Food Time
Oily fish Up to 3 months
Smoked fish Up to 3 months
Other fish Up to 6 months
Oysters Up to 6 months
Prawns Up to 3 months
Squid and Octopus Up to 3 months

Freezing Pastries

Most pastries freeze extremely well (my own freezer is generally filled with them). A few things to keep in mind :

  • Custard and cream don't freeze terribly well (they both soak into the base). If you're planning to add some, wait until you're ready to eat it.
  • Meringue toppings tend to toughen during freezing. As with the cream, add it just before serving.
  • Sheets of pastry are notoriously difficult to separate when frozen. Make sure there's a sheet of freezer paper between each one.

Overall, it's a straightforward process. Place individual items in bags or plastic containers; and stack sheets with freezer paper between each.

Both cooked and uncooked pastry can be frozen.

How long does it last?

Pastry generally keeps well. A few approximate times :

Food Time
Baked pastries with fruit fillings 3-4 months
Baked pastry (plain) 2-3 months
Unbaked pastry 6-8 weeks
Pumpkin pie 4-5 weeks

What not to freeze

Foods that do not freeze well include :

  • mayonnaise
  • cream puddings and fillings
  • custard
  • gelatin salads
  • cheese
  • the whites of hard-cooked eggs and uncooked egg yolks
  • gravies made with wheat flour
  • spices

Final thoughts on freezing food

Freezing food can be a great way to save money, make sure your favourites are available all year and cut down on food waste. Leftovers are often ready for re-use in another form.

As far as food safety is concerned, freezing food - for any length of time - is safe to eat. The various 'best before' times noted above simply refer to the flavours and appearance of the food.

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