Food - Bee Wilson resists a bloodless revolution

"This is without doubt an ingredient that has revolutionised modern cooking," writes the inestimable Delia Smith. She does not mean sliced bread. Nor is she referring to lemon grass, rocket or quince cheese. Nor, for that matter, to any of the basic convenience foods that genuinely have transformed modern home cooking, such as dried pasta, frozen peas or tinned plum tomatoes. No, the revolutionary product at stake is actually Marigold Swiss vegetable bouillon - dried vegetable granules in a tub. If a revolution really has taken place, it has been sudden, bloodless and silent.

Over the past five years or so, this product has achieved a remarkable ascendancy among British food writers. Nigella Lawson often praises it. Delia thinks it is a "star". Sainsbury's magazine has a house policy of mentioning Marigold as an alternative to stock in all recipes printed. It is very hard to explain this trend, given that Marigold bouillon is neither new nor outstandingly delicious.

When it comes to stock, cookery writers used to fall into one of two schools of thought: those who argued that only fresh stock would do, made from bones, bay leaves, carrots, celery, parsley and onion, simmered for several hours, regularly skimmed for scum and well strained through muslin; and those who admitted that they used stock cubes. Elizabeth David moved from the second school to the first. In her revised edition of Italian Food in 1987, she wrote that, in the days of meat rationing, "sometimes I had no alternative but to use the then recently introduced Swiss bouillon cubes. In those days, they seemed quite acceptable. Now I don't find them so. They taste predominantly of salt and monosodium glutamate."

There is no monosodium glutamate in Marigold Swiss vegetable bouillon powder. Its unique selling point is that it is as convenient as stock cubes, yet seems more "natural". It is vegan, and is free of genetically modified organisms, artificial flavouring, colouring and preservatives. It is also free of character, except for a slight celery-water savouriness and a little warmth from turmeric and nutmeg. Yet it is just this blandness that makes it the ne plus ultra of the instant stock world.

Marigold Swiss vegetable bouillon is an unlikely example of the winner-takes-all culture. It certainly doesn't look the part. The packaging belongs in a Seventies fitted kitchen: a clunky orange plastic lid on a clumsily designed cardboard cylinder. Marigold is barely advertised. It doesn't taste like a champion, either. There is nothing offensive in the liquid produced when you dissolve two teaspoonfuls in a litre of hot water, as directed. A yellow broth with green flecks of dried parsley, it is vegetably, salty and has no unpleasant aftertaste. But I can't say I'd want to drink it as a "delightful beverage", as the label suggests.

It is all right when used to make vegetable soups, although there hardly seems much point, given that most simple soups, if lovingly made and well seasoned, taste just as good made with water. And Marigold would be useless for the kind of soup - avgolomeno, say, or beef consomme - that depends on fine, gelatinous stock, and worse than useless for producing the meat essences and glazes of classical sauce-making. Yet Marigold addicts seem to use it for almost everything: gravy, slow-cooked French onion soup, casseroles, risotto. The strange thing is that, for many of these dishes, a despised stock cube is superior to Marigold, if you have no proper stock to hand. Marcella Hazan, the queen of risotto, sometimes uses a much-diluted chicken stock cube in place of broth. You can also make a good quick summer soup from a chicken stock cube dissolved in hot water, combined with yoghurt and lemon juice, chilled, and tempered with diced, deseeded cucumber and mint; the same soup made with Marigold is somehow unappetising. But then, revolutions are not noted for their taste.