I could not have imagined, nearly eight years ago, when this newspaper was launched and I began this column with one in praise of the tomato, that I would one day write in the same space about a genetically engineered tomato. But such a tomato, Flavr Savr, has just been approved (it was voluntarily submitted by its maker, Calgene) by the US Food and Drug Administration.

The qualities of the Flavr Savr, which is expected to reap a bonanza for its creators (Calgene has a joint development agreement with Unilever, the world's largest maker of margarine), are that it stays firmer and ripens longer on the vine. This has been achieved by isolating the gene that produces polygalacturonase (PG) and reversing its action. PG is responsible for ripening a tomato. Ripening is a form of decay; PG breaks down the pectin in the tomato's cell walls and allows it to decay (ripen) and spread its seeds. By reversing the action of the gene, the process is delayed.

Flavr Savrs stay fresh for 10 days longer than normal tomatoes. They can be riper when shipped. This sounds like good news; it is certainly better than what happens to our average market tomatoes, which are picked green and gassed to induce ripening. The new tomato ought at least to be the equal of top-of-the-market hydroponic tomatoes, greenhouse tomatoes and the wan and flavourless Jersey and Dutch tomatoes. In short, it will be a useful out-of- season filler.

It is plump, regular and good- looking; it is firm, juicy and supple; it is red and has a thin skin. In fact, it will look like a damned good buy. But how will you know if it's a Flavr Savr or a sun-ripened tomato? You won't. Calgene is launching the new product labelled and explained; but how long will labelling last?

The interest of cooks in this matter is considerable, especially in northern countries. Along the Mediterranean, the tomato is such a staple that the surplus summer crops are available for bottling, canning, drying and other forms of preservation (the bulk of these processes taking place at home); that surplus also provides a reliable supply of sun- ripened tomatoes for use in sauces throughout the year.

But in the north we buy tinned tomatoes. And when we buy Italian tinned tomatoes, we generally get a good facsimile of the real thing, because Italy produces a wide variety of tomatoes, some of them specially adapted for canning, with a greater concentration of flavour in the juice than the pulp.

According to all reports, this last factor is precisely the weakness of the Flavr Savr. The Flavr it saves is nothing to write home about: I have seen it described as 'watery', 'over-sweet', 'weak- tasting' and so on. It is long on texture and short on taste. What this means is that it is no substitute for any dish that requires a real tomato - such as tomato salad, a genuine tomato-based pasta sauce, and so on.

Calgene's tomato is, of course, only the forerunner of genetic- engineering applications to our foods. Naturally grown fruit and vegetables, as any farmer knows, are subject to pests and viruses; so it is tempting to develop varieties which would be disease-resistant. In Kalamazoo, Michigan, the Asgrow Seed Company is working on engineering cucumbers, melons and squash that will be virus-resistant. Other companies are developing plants with new, bacterial genes resistant to insects, and still others are working on cooking oils that will contain less saturated fat, on grains with higher protein levels, on potatoes that absorb less fat when fried.

Some of these will require very careful monitoring indeed, for there is already research to suggest that inserted anti-viral genes can recombine with plant viruses to produce wholly new viruses - with devastating effects.

True, horticultural tinkering is as old as mankind, and has generally been hugely beneficent. It has created plenty, and vastly increased variety - not to speak of beauty. The aim of such fiddling with nature has been to produce hardier varieties of fruits and vegetables, to adapt them to local climatic conditions and, above all, to provide a greater range of flavours and uses.

So far, all these extensions of our food have been 'natural', the result of careful breeding and cross-fertilisation. With the Flavr Savr we are into a brave new, and untested, world, the probable result of which will be greater standardisation, wider marketing and - where new products are not 'owned' by a single company - lower prices and greater year-round availability. This, in turn, as the Mackintosh and the Golden Delicious did to the apple market, will mean fewer varieties and the imposition of an overall blandness.

Already, those born after the war have no memory of the great garden that England was. For nigh on 50 years we've been fed on the pale products of artificial cultivation. And now the Flavr Savr. To destroy taste memory is to destroy cooking.