FREEZER BASICS

HOW A FREEZER WORKS

I could seemingly blind you with science here and talk a great deal about compressors, condensers and evaporators but suffice to say, if you want an easy explanation, a freezer works on a simple principle - the extraction of heat from the cabinet. The crucial parts are the ones I have already mentioned and the magic ingredient is the refrigerant vapour. For those of you more technically minded here goes:

When the freezer motor is started, refrigerant vapour is drawn from the evaporator by the compressor and is forced under pressure into the condenser. Here the heat absorbed in the evaporator, together with that generated in the compressor, is given off, and as the vapour cools it condenses into a liquid. The liquid refrigerant is then forced into the evaporator at high pressure through a fine-bore capillary tube or expansion valve and the sudden fall in pressure as it passes into the evaporator causes the refrigerant to boil fiercely, and to change back to vapour (a process that absorbs heat). This is what freezes the food and keeps it frozen. The vapour then passes on to the compressor so that the whole cycle can begin again.

Freezing is one of the easiest and safest methods of food preservation, and the one that preserves food closest to its original state in terms of flavour, texture and nutritional value. If correctly prepared, packaged, stored and defrosted, frozen food will be indistinguishable from its fresh counterpart.

Freezing works by reducing the temperature of the food to a point at which chemical changes are reduced and micro-organisms become inactive. As soon as the food is defrosted, deterioration will begin again.

CHOOSING A FREEZER

Once you have made the decision to buy a freezer, the type you choose will be determined largely by the services you expect from it, the size of your family, the space you have available for it, the money you want to spend and the range of produce you intend to freeze. The needs, for example, of a family with a kitchen and fruit garden, and an avid interest in cooking, may differ from a family of working adults and children alike with staggered meal times or perhaps a working couple without children.

Whatever your needs it always seems better to think big. I have lost count over the number of times that I have heard friends say that they wish they had gone for the bigger model, wished they had more space to take advantage of a particular bargain and bless the friend who had space to cope with an overflow from my freezer during one very busy entertaining period. The more scientific and mathematical might like to know that as a rough guide you should allow 85-113 litres/3-4 cu ft of space for each member of the family. In other words a 350 litre/12 cu ft model is really the smallest you should consider for a family of four people. Remember that each 28 litres/1 cu ft of freezer space will only store between 9-11 kg/20-25 lb food.

There is a large choice of freezers on the market but basically they fall into three categories.

* THE CHEST FREEZER

* THE UPRIGHT FREEZER

* THE COMBINATION REFRIGERATOR/FREEZER

Always spend time comparing prices in as many shops and discount houses as you can before buying. Remember too that you are also more likely to get reliable after-sales service from large reputable manufacturers.

THE CHEST FREEZER

Recognised by their box-like appearance with hinged top-opening lid, the chest freezer's capacity ranges from about 125 litres/4 cu ft up to 775 litres/25 cu ft. Large models usually have counter-balanced lids which will stay open in any position and thus leave your hands free for searching or packaging.

Some models are fitted with a partition to separate the fast-freeze section from the main storage section. In some models the fast-freeze section is separately refrigerated. Some hanging baskets are usually supplied with the freezer, though more may be purchased separately.

ADVANTAGES

1. Because of its relatively simple construction it is usually cheaper to buy than an upright or combination refrigerator/freezer.

2. It is usually slightly cheaper to run than an upright or combination refrigerator/freezer.

3. As items are stacked on top of each other, it is possible to store more food per litre/cu ft.

4. It is considered better for storing large and irregular pieces of meat and large turkeys since there are no shelves to limit space.

5. It usually requires defrosting only once per year.

6. The lid can be used as a work surface in the kitchen.

DISADVANTAGES

1. It takes up proportionately more room than an upright and combination refrigerator/freezer.

2. It can be difficult to find items unless you have worked out a good system.

3. It is more difficult to manage for small or elderly people.

THE UPRIGHT FREEZER

The upright freezer resembles a refrigerator in appearance and will take up a similar amount of floor space. It has a front-opening door, several shelves, often adjustable and/or pull-out baskets so that the food can be seen and easily removed. Some models have a special fast-freeze shelf, drawer or compartment, while in others any shelf can be used for this operation. Again there are a wide range of sizes ranging from around 57 litres/2 cu ft to 566 litres/20 cu ft.

ADVANTAGES

1. Ideal where floor space is limited.

2. Packages are more easily accessible.

3. There is possible work surface on some of the smaller models and some are designed to fit on existing work surfaces if this is more convenient.

4. Sliding baskets are useful on some models and are ideal for those with limited mobility.

5. Many have automatic defrosting.

DISADVANTAGES

1. They are generally more expensive to buy than chest models.

2. They are not always able to take large or awkward-shaped packages on their shelves.

3. There is seemingly less storage space per litre/cu ft than in a chest type.

4. They are slightly more expensive to run than chest types, but not as much as is usually imagined.

THE COMBINATION REFRIGERATOR/FREEZER

Some manufacturers produce 'twin-units', which are two separate front-opening models combining refrigerator and freezer, the refrigerator usually having the same litre/cu ft capacity as the freezer. These may be designed to stand on top of each other or side by side. The upright combination is particularly suitable for limited kitchen space.

The freezer unit has a separate temperature control which can be lowered for fresh and pre-cooked foods, but the freezing capacity is usually fairly small, up to about 198 litres/7 cu ft and capable of storing a maximum of 63 kg/140 lb frozen food.

ADVANTAGES

1. Shelves and food are easily accessible like in the upright freezer.

2. It is better suited to long-term storage of commercially frozen food rather than those who freeze large quantities of home-grown food.

3. It takes up very little floor space.

4. Many have automatic defrosting.

DISADVANTAGES

1. Limited storage space and capacity.

2. It won't easily store large or bulky items.

3. Marginally more expensive to run than a chest freezer of the same size.

4. More expensive to buy than a chest or upright freezer.

SITING A FREEZER

This can be almost anywhere which is well ventilated and not damp. As you do not go to the freezer as often as the refrigerator it could be in a spare room or the garage.

If you intend to freeze a lot of your own produce either from the garden or home-made dishes, it is more convenient if the freezer is in the kitchen. Try not to place it next to the central heating boiler or cooker, or it will have to work that much harder at maintaining its low temperature.

Condensation is often quite noticeable when a freezer is stored outside in a garage or in a not so dry cellar. To maintain low temperature inside the freezer it pushes out warm air which, on hitting cold and sometimes damp atmospheric conditions, turns to moisture vapour and deposits itself on the outer casing of the freezer as dampness. Where this happens, owners should dry off any condensation when noticed so that the dampness does not penetrate into the working parts of the freezer (where they could cause rust).

Generally speaking, a freezer stored in the garage should be treated the same as a car, ie kept dry and wax-polished frequently; keep the freezer on boards or bricks so that the metal surfaces are kept clear of the damp.

INSURANCE

Although the freezer is a reliable appliance, some insurance policies include cover for any loss of food through accidental switching off of the power supply and accidental damage to the freezer itself. Frozen food insurance can be obtained to cover loss of food through breakdowns and accidental failure of the power supply. Breakdown and repair insurance (labour and materials) is also available.

It is sometimes possible to have this insurance included in your house policy but since most of these policies are not specific they do not always include the full range of items that you would get from a specialised freezer insurance broker.

MOVING HOUSE

If the distance isn't too far and removal men are willing and able (it might be very heavy) it may be possible to take the freezer with the food inside. Turn the fast-freeze switch on for 24 hours beforehand to get the contents down to as low a temperature as possible, and, if not packed full with food, stuff with crumpled newspaper so that items will not move about, possibly damaging the interior wall of the freezer. Do not run down stocks if you are moving the freezer in this way, the more food the better, but make sure it can still be lifted. Make sure it is the last item to go on the removal van and therefore first off establish beforehand where it is to go and don't forget to plug it in as soon as possible. Cakes and vegetables and those items which are already cooked will suffer a particular quality loss and may be ruined by a rise in temperature if there is too much of a delay.

If you can't take your freezer full of food then run down stocks as much as possible and pack the remaining items in insulated boxes for the journey. Your removal firm may even be able to supply these. Pack with a little dry ice if you can. Fast-freeze such food for 24 hours beforehand, pack into insulated containers at the last minute and return to the freezer as soon as possible (when it has reached freezing storage temperature). Use insulated containers or make your own temporary ones using cardboard boxes lined with polystyrene begged from your greengrocer, for storing food for short journey times. Take it with you in the car if you can and unpack into the freezer as soon as possible.

CLEANING AND MAINTENANCE

When you first receive your freezer do take the time to sit down and read the instruction booklet that comes with it. It will tell you all you need to know about the cleaning and care of your own specific freezer.

Initially wash out the interior thoroughly before switching on your new freezer. Wash with a solution of 15 ml/1 tablespoon bicarbonate of soda to 1.2 litres/2 pints warm water and wipe completely dry. Plug the freezer in and tape over the switch to prevent it accidentally being turned off. Check with the manufacturer's instructions that the temperature control has been properly set. Leave the freezer on for 12 hours before putting in any food. This will ensure that the correct storage temperature of the freezer has been reached and that the freezer is working properly. Ideally do not fill the freezer completely in one go but gradually; how much fresh food is put in at one time will depend upon its daily freezing capacity.

General maintenance of the freezer is comparatively simple; it should be professionally serviced once a year, and there should be a daily emergency service available in case of breakdown. Check out what services your retailer offers BEFORE you purchase.

Wipe the exterior of the freezer with a damp cloth and dry well. Use a wax or silicone polish occasionally to protect. If the top is used as a work surface in the kitchen then protect it with wipe-over contact paper. This prevents staining, scratching and general wear and tear to the surface.

DEFROSTING THE FREEZER

Usually this is only necessary once a year for a chest freezer and twice a year for an upright or combination refrigerator/freezer, when the contents are at their lowest. This may well be just before the summer season's fruits and vegetables are ready to be harvested; or before you start to stock up for a big celebration like Christmas.

If the freezer is used a great deal and is in a relatively warm place, frost may accumulate on the inside of the cabinet. It is as well to remove this as it appears, with a plastic spatula or scraper.

For complete defrosting, remove the contents; wrap the slow-thaw items in newspapers or a blanket, and put the quick-thaw items into the refrigerator which has been turned to its lowest setting. Remove as much ice and frost as possible before it has a chance to defrost completely, using a scraper and a special dust pan and brush. Wash with lukewarm water. Dry with a clean cloth and set the freezer to fast freeze to reduce the temperature quickly before returning the food.

Do not use a metal scraper, which may puncture the walls of the cabinet.

It is quite possible to defrost a freezer in 20 minutes and therefore it is not such an outfacing job as it might at first seem!

FREEZER BREAKDOWN: WHAT TO DO IN AN EMERGENCY!

It is the wise cook who invests in a freezer thermometer. For, when placed inside the cabinet, it will accurately record the temperature in the freezer and may prove the very first warning signs that all is not well. Check the temperature occasionally and, if your freezer is in a garage or cellar, then seriously consider fitting a freezer alarm that will give you an audible warning that there is an increase in temperature that needs attention.

Many freezers have a warning light which comes on if there is a temperature rise inside the cabinet. If a temperature above -18°C (the ideal storage temperature) is recorded then check the following before calling your engineer:

1. Are the lights working on the control panel of the freezer? If yes, then move to Point 5, if not:

2. Check that the plug is in and the switch is on. A piece of tape or plaster over the plug and switch is a good idea and label it 'do not switch off'.

3. Has the plug blown a fuse? (This is easily replaced but you should ask yourself why, in case it could happen again.)

4. Look at the mains supply and check that no fuses have gone there.

5. Is there or has there been a power cut? Your mains electric clock is a good guideline as to how long this may have been.

6. Is the lid or door of the freezer firmly shut? Especially with an upright freezer a faulty seal on the door will soon let in warm air. This can be proved if there is a build-up of ice around the door or lid of the freezer.

7. If the weather is hot or you have been 'in and out' of the freezer many times over a short period this may affect the temperature.

8. Has too much warm fresh food been put into the freezer? Even with the fast-freeze switch on, this will increase the temperature of the freezer.

9. Check if there is adequate circulation of air around the freezer and that the grill is not blocked with dirt.

If you have checked all the above points, then call the engineer. Always have the name and phone number of an engineer by the freezer. Remember there is no panic if your freezer does break down, as the contents of a full freezer will be alright for up to 24 hours before the food begins to defrost. The temperature will not normally reach -10°C in this time. Resist the temptation to open the lid or door whilst the freezer is off and also for several hours after it has started working again.

In the event of a freezer breakdown or long power failure, and emergency steps are not taken (if you are away for a few days, for example), the following information will help in your decision on what to do with the food inside your cabinet:

1. If food is beginning to defrost, but there are ice crystals still in the centre of the food, these foods may be refrozen.

2. If there are no ice crystals but the food is still very cold, then bread, baked unfilled products and fruit can be refrozen. Raw meat, poultry and fish should be thoroughly cooked and then refrozen. Remember storage times will then be as for the cooked product. Vegetables should not be refrozen but can be eaten immediately, after being thoroughly cooked. Pre-cooked dishes and ice cream should not be refrozen.

3. If the food isn't even cold then it is not advisable to refreeze any of the food even after cooking, but can usually be eaten immediately after being thoroughly cooked.

WHAT IF THERE IS A POWER CUT?

If the freezer is full the contents will probably remain frozen for almost 24 hours, if only half full then up to 12 hours, providing the freezer has NOT been opened allowing warm air inside. Resist the temptation to look and see if the food is alright.