The proof of the pudding...

There are few things that can be done to improve the taste of a ripe pineapple, says Heston Blumenthal. But roasting the fruit is one of them

A ripe pineapple is a wonderful fruit - a bit exotic to look at, intoxicating to smell, sweet and clean to eat; just the kind of sensations to blast away the winter blues. And we're coming into the prime time for pineapples about now. Just make sure that you buy a really ripe one, because pineapples don't go on ripening once they've been cut from the tree. This means that they have to be picked as near to ripeness as possible if we're going to get that full flavour. Mind you, it's easy to tell if a pineapple is ready to go - just give one of its leaves a sharp tug, and if it pulls away from the fruit relatively easily, buy it at once.

So, once you've got your perfect pineapple, what do you do with it? The obvious answer is to break it up and eat it as soon as possible. But suppose you wanted to do something more elaborate with it. Here are three recipes that form the constituent parts of a fantastic dessert: roast pineapple with pineapple and chilli jelly and crab syrup. The crab syrup may seem a bit on the wild side, but it is completely delicious, I promise you, and it works wonderfully with the roast fruit and the jelly, as it does with most other tropical fruits. Of course, you can always leave out the syrup if you really don't fancy it - the dish will still taste delicious.

In any case, it's the jelly that is really interesting. Under normal circumstances, you can't make a jelly using raw pineapple and gelatine, because the pineapple contains bromelin, a powerful enzyme that breaks down protein. It's so powerful, in fact, that if you eat enough of it, your teeth will fall out. In the earlier part of this century, a ship was wrecked off the coast of one of the Indonesian islands, and the crew spent weeks living off nothing much else but pineapples. When they were finally rescued, most of them had no teeth left - the bromelin in the pineapple had eaten away their gums. (Not to worry, though - you'd have to eat an awful lot of pineapple before anything so drastic happened; and anyway, when we swallow the fruit our bodies produce hydrochloric acid, which destroys bromelin.)

Obviously, an ingredient with such qualities should be able to be put to use in the kitchen. A few years ago, I read about an experiment carried out by the great Nicholas Kurti, physicist at Oxford University and one of the original leaders in studying the science of cooking. Basically, he was looking at pineapple juice as a meat tenderiser, and had injected meats with pure pineapple juice. Following his example, we promptly ordered some hypodermic syringes at the restaurant and set to work injecting different pieces of relatively lean beef, lamb, duck and pork fillet with fresh, uncooked pineapple juice, and then left them for between one hour and three days before cooking. To my amazement, all the pieces of meat, once cooked, were tenderised to varying degrees of unpleasantness, and in the worst instances had literally been eaten away. So, pineapple does indeed tenderise meat - but you have to use it very carefully if the meat is to remain edible after cooking.

You may remember that I suggested adding some pineapple to a dish of lentils in the first set of recipes four weeks back. That's because lentils carry just about the highest protein levels of any vegetable, and adding pineapple to the water when cooking gives them an almost creamy consistency, which cannot be achieved otherwise. It is important to bear in mind, however, that the lentils should be heated very gently and for a short period; if they are brought to the boil quickly, the bromelin will be destroyed before it has had time to do its work.

Heating and hydrochloric acid aren't the only antidotes to the effects of bromelin. Chilli has much the same effect, hence the ability to make a jelly using raw pineapple juice, chilli and gelatine. It's an intriguing effect, with the heat of the chilli coming up through the pure, sweet fruitiness of the jelly. It's the kind of combination you often find in Mexico and southern Italy.

All recipes serve six.

Roast pineapple

3 vanilla pods (or a few drops of top-quality vanilla essence)
125g caster sugar
225ml water
1 dssp dark rum
1 ripe but firm pineapple, weighing about 1.5kg

Pre-heat the oven to 225C/425F/gas mark 7. Scrape out seeds from the vanilla pods (if using) and set aside. Put the sugar in a casserole and place it over medium heat. Ideally, having a pastry brush or similar and a cup of cold water to hand will make this next part of the job easier. While the sugar is caramelising, generously brush around the inside of the pan with the wet brush, allowing the water held in the bristles to run down the inside of the pan. This will prevent the sugar from burning and also help to cook it at an even rate. In any event, do not be tempted to stir the sugar, else it will clump together.

When the caramel has taken on a lovely dark amber colour, add the vanilla pods and seeds (or the vanilla essence) and the ginger, then pour in the water to prevent the syrup from becoming any darker. Be careful not to take the sugar too far, or the caramel will become bitter.

Bring the mixture up to the boil and, after a couple of minutes, add the rum, then remove the pot from the heat and set aside. Next, strain the syrup through a fine sieve.

Peel the pineapple, then roast it in one piece for an hour, basting regularly with the syrup. Carve the fruit into slices and serve warm with a spoonful of the following jelly on the side (so that it does not melt) and the syrup from this week's final recipe poured over.

Pineapple and chilli jelly

400ml pineapple juice
1 fresh red chilli, deseeded and very finely chopped
2 gelatine leaves

Place the gelatine leaves in water to soak, according to the instructions on the packet. Gently heat the pineapple juice and chopped chilli, but on no account let it come to a boil. Taste while heating, until the juice is sufficiently infused with the chilli that you can taste it. Remove the pan from the heat once the chilli flavour is at a level you like, and pass the mixture through a fine mesh sieve.

Take a small amount of the liquid and reheat gently with the soaked gelatine until the latter has completely dissolved. Pour this mixture into the rest of the pineapple and chilli liquor, then pour the whole lot into a container and put in the fridge to set.

Just before serving, mash the jelly a little with a fork, as this really improves the overall texture.

Crab syrup

1 crab shell, broken up - use the white and brown crabmeat in another dish, such as a crab salad, a sandwich or even a soufflé
100ml olive oil
125g granulated sugar
125ml water

It is easiest to smash up the crab shell by placing it under a cloth, as this minimises the mess. Heat the oil in a casserole dish or ovenproof pan. Once this is smoking hot, add the broken pieces of shell and roast in the oil, turning regularly, until they have turned lightly golden (this should take between five and 10 minutes), then take off the heat.

In another pan, bring the water and sugar to a boil, then pour into the crab shell pan and cover with a lid. Leave to infuse in the oven for four to six hours at the lowest possible setting, or at room temperature for 24 hours. Finally, strain the syrup through a fine mesh sieve (this could take a fair old time, as there will be a lot of liquid left in the crab shells), and then again through muslin

Heston Blumenthal is chef/proprietor at the Fat Duck, Bray, Berkshire.

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