A pinch of umami . . .

Just as I was thinking about posting on the subject of umami (following last night's delicious umami-rich supper of roast haddock and mushrooms) an animated discussion has broken out on Twitter on the virtues - or otherwise - of adding Marmite to a spaghetti sauce.

It was prompted by Nigella's discovery, revealed in Observer Food Monthly today, that adding Marmite to a classic al burro sauce makes for a particularly tasty, child-friendly meal, a tip she got from her mentor, Italian food writer Anna del Conte.

Marmite, of course, is rich in umami - the so-called 'fifth taste' (the others being sweet, sour, salty and bitter) It's a kind of intense savouriness you find in ingredients such as aged parmesan, roast chicken skin, slow roast tomatoes, porcini, fish sauce and dried seaweed like kombu and makes every dish that contains it taste lip-smackingly appetising.

The great thing about it is that it's not expensive. You only need a little to create the effect which makes it a great asset to the frugal cook's larder. Last night I cooked the simplest of dishes in my Remoska cooker (my new obsession) that involved sweating off a small onion, adding 250g of sliced chestnut mushrooms, cooking them for about 15 minutes then topping them with a couple of haddock fillets and cooking a further 6-7 minutes until the fish was cooked. The magic ingredient was a large pinch of the umami-rich poudre de ceps, I mentioned a couple of months back, which intensified the umami flavour of the mushrooms.

If you're going to France this summer look out for it in those sections of service stations that stock local food products (I think I bought mine in the Auvergne) or, if you can't wait that long buy a tin of the bizarrely named Shake O'Cini which has a similar effect. Failing that, add a little Marmite to your mushrooms - along with a good knob of butter. It might sound as weird with fish as it does with spaghetti but I bet it will work.

Do you consciously add umami to your cooking and if so, in what way? (I expect a full answer on this from Sig of Scandilicious, one of the three student collaborators on our forthcoming Ultimate Student Cookbook, who has studied the subject in depth ;-)