How to make friends with your freezer
Vegetables packed with nutrients, fish that's often better than fresh – it's time we stopped seeing frozen food as second best, says Annie Bell
Thursday 03 February 2011
My relationship with my freezer revolves around indifference more than love. I see it as a convenience, that rarely extends further than ice cubes, stock, frozen petits pois and ice cream. The reason for this rather negative view lies with the failed attempts to freeze numerous dishes and leftovers that after defrosting have been so far removed from the dishes they started off as, they have landed in the bin.
Why is it that what went into the freezer as a respectable shepherd's pie or fish stew emerges with the consistency of cotton wool, bread that went in fresh comes out tasting stale, and as for those ice cubes, you know I could swear they taste of raw onions. And yet on the occasions when I buy in some ready-frozen convenience food, be it fish fingers, frozen prawns or samosas, the quality is perfectly respectable.
So I was intrigued by the publication of the world's first report into frozen food. Compiled by researchers at the Centre for Food Innovation at Sheffield Hallam University, and Refrigeration Developments and Testing Ltd at Bristol, its findings convincingly make the case that frozen food should form a major part of our consumption in the future. It offers food that has an extended shelf-life without recourse to preservatives, seasonal foods all year round, produce that is often more nutrient-rich than the fresh equivalent, and that has a low carbon footprint. That's quite a hat-trick.
So on that basis, as one of the great unconverted, it seemed time to revisit this technology to try to understand more about the different results and varied quality that we experience at home, and to see whether as food lovers we could perhaps make better use of the facility.
What happens when we freeze food?
Food that is frozen is subjected to sub-zero temperatures that cause the water in the product to turn to ice crystals. And it is the size of these crystals that determines how successful the process will be.
In short, they are the big enemy, and the speed at which you freeze food is all-important. The faster the freeze, the smaller the crystal, and the more intact the produce once defrosted. The converse is that the slower the freeze, the bigger the crystal and the greater the damage caused to the basic cellular structure or fibres of the produce, which is why, on occasions, perfectly delicious dishes that go into the freezer at home come out in such a sorry state.
Industrial freezing technologies are much more sophisticated than anything we can achieve at home. Essentially they allow for very rapid freezing, sometimes within minutes.
The industry employs two basic techniques to rapid-freeze produce. The first uses ammonia to chill the air, which then circulates around the product; the second uses liquid nitrogen to vaporise around the product on contact, which is often the choice of method for freezing fish and other delicate items. In the case of freezing fish, this sometimes takes place out at sea within hours of the catch being landed, while vegetables or fruits are also frozen within hours.
While it is easy enough to get excited about a 30-minute running cycle on a dishwasher and a tumble dryer with sensor control, most of us balk at spending thousands on a home freezer. We're not asking it to run a bath, we just want it to keep the ice cream in a solid state and offer up ice cubes on demand.
So what is it that upmarket home-freezing systems have to offer? First, we have to look at how a standard fridge-freezer operates, with a single motor. The system kicks off with a compromise, as it seems we cannot keep both our fridge and our freezer completely happy with one air supply.
Cold, dry air from the freezer is pumped into the fridge, which sucks the moisture out of the produce, hence the cheese that cracks if it isn't covered. The moist, warmer air is then pumped back into the freezer with the various odours it has gathered from the fridge, hence those ice cubes that taste of raw onions, and the food containers become encased in a layer of frost as the moisture in the air freezes around them. And so on, in a continuous cycle.
More sophisticated systems offer dual compressors, one for the freezer and one for the fridge, ensuring the ideal temperature and conditions within each, with air that doesn't cross over. Beyond this, they also offer rapid freezing. A sub-zero freezer, for instance, can freeze an item in 30 minutes, which would take two hours in a standard one, so this gives results more akin to the frozen produce we can buy from shops. We're probably not all going to rush out and buy a new freezer, but it's worth being aware of this technology and putting it on your wish list should you be shopping for a new one.
A green technology, the way of the future?
The Waste and Resources Action Programme (Wrap) estimates that something in the region of 30 per cent of fresh food is thrown away. Frozen food cuts down enormously on the potential waste that can occur at various stages of the journey from farm or sea to plate. And there are significantly fewer food miles involved in eating veg that was harvested in season and frozen close to home, rather than shipped halfway around the world out of season. Given that it keeps pretty much indefinitely (providing it is frozen at minus 18C or below), you consume what you need when you need it.
Frozen vegetables have more nutrients than fresh vegetables
One of the great misconceptions is that fresh vegetables contain more nutrients than frozen ones. It is a hard one for passionate cooks to swallow, because we would rather believe otherwise, but vegetables start to lose their nutrient value from the moment they are picked. Fresh green beans can take up to nine days to reach a supermarket, then hang around the shelves for another few days, and then in the bottom of your fridge for a few more. This means they have up to 45 per cent less nutritional value than the green beans that had their vitamins locked in by freezing within hours of being cooked. Birds Eye Field Fresh Garden Peas, for instance, contain up to 30 per cent more vitamin C than their fresh equivalent.
We can go a long way to helping ourselves at home by chilling food prior to freezing, regularly defrosting our freezers to ensure they're working efficiently, and not overstocking them.
Transferred flavours or scents are easily rectified by sealing food in airtight freezer bags or containers - but never clingfilm, which will disintegrate.
However Martha Stewart it may sound, a list on the freezer door with a note of what's in it saves you from discovering long-lost dishes you didn't know still existed when you come to defrost it.
Most foods can be cooked from frozen, except for exceptionally large items such as a turkey. Adjust the cooking time accordingly.
Almost anything can be frozen, though avoid potatoes, which tend to turn to cotton wool, and high water content foods such as soft fruits. Oily sauces can also be problematic.
Delicate, watery ingredients such as soft fruits will be best cooked before they are frozen.
What to buy
The frozen-food market has long pitched itself at a lower price point than the fresh-food market, perhaps one of the reasons we tend to treat it with suspicion. But much of this saving is due to the harvesting of the produce in season and a lack of waste, rather than anything sinister. Aside from fish, it will never match fresh food in flavour and texture, but there is plenty for the keen cook to exploit.
This is where food lovers should prick up their ears. Fish probably freezes better than any other protein source. Most of us are familiar with opening a packet of "fresh" fish and thinking, "Well, it's not off, but it's not fresh, either." "Fresh" fish can sit for days in the hold of a boat before being unloaded, followed by its subsequent journey from market to shop to fridge. But Young's, for instance, which sources its fish sustainably, freezes it within hours of being harvested, as does Marks & Spencer, whose frozen fillets are truly excellent and have that milky sweetness that belongs to fresh fish by rights. Poach them from frozen in a little milk with a bay leaf for 8-10 minutes in a covered pan and they are at the ready for a pie or fish cakes, or for serving plain. Otherwise, defrost and drain on kitchen paper, and fry or grill them.
With Iceland selling 1kg bags of frozen veg for £1 (it can be 10 times that for fresh), there is no need for anyone counting their pennies to go without their five a day. The only small rub is that the texture of most of it has little in common with the real thing. This is largely because they are blanched prior to freezing to halt any enzymatic activity, so you are cooking them for the second time, and in water that is well below boiling point to begin with.
Still, they make an excellent base for soups and stews: add them to pasta dishes, or make, for instance, a broccoli purée with butter, crème fraîche, sea salt, black pepper and nutmeg. They are also great for busy parents running two dinner shifts, who can't see their way to preparing fresh veg to go with the kids' pasta.
These are excellent stirred into cooked dishes, and capture to an impressive extent the scent of the fresh herb, if not the texture. They are streets ahead of the dried equivalent, and great if you live in the country or don't get to the shops regularly.
Freezing fruit at home tends to result in jam by the time you have defrosted it. Take advantage of the sophisticated freezing technology within the industry to avail yourself of delicate out-of-season fruits such as blackcurrants, gooseberries and raspberries, which would cost you a fortune had they been flown in from the other side of the world.
Little frozen cocktail eats are the answer to the hostess's prayers. Pastry freezes beautifully, as do all those dainty oriental eats that you would never dream of trying to make yourself. M&S has an excellent range.
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