18.5 Cooking fruit; acid, heat and color

Most fruit is served raw, but much of it can also be cooked. Fruit can be grilled or broiled, baked, sautéed, deep-fried, poached, simmered, or preserved.

Sugar, acid and alkali

Fruit goes soft very quickly under heat, and once it is mushy it cannot be undone. Three things change how fast that happens:

• Sugar firms fruit. Cooked with sugar, the fruit slowly takes the sugar into its cells and holds its shape better. The cost is time: fruit poached in a sugar syrup takes longer to become tender.
• Acid, lemon juice above all, also helps fruit keep its structure.
• Alkali, such as baking soda, does the reverse: the cells break down faster and the fruit turns to mush.

Knowing when it is done

Fruits react to heat in so many ways that no single test fits them all; judge each one in its own recipe. As a rule, cooked fruit is done when it is just tender: a fork or the point of a small knife slides in. Fruit simmered for a compote should be softer, cooked until it is just about to fall apart. Residual heat keeps cooking fruit after it leaves the pan, so stop a little early. Trust your eyes, hands, nose and tongue, not the clock.

Broiling and grilling

Grill or broil fruit only long enough to caramelize its sugar, and do it fast, before the fruit breaks down. Pineapples, apples, grapefruits, bananas, persimmons and peaches all work. Cut them into slices, chunks or halves, and top them with sugar or honey, which adds flavor and helps them brown; liqueur, lemon juice, cinnamon or ginger add more. Use an oiled sheet pan or broiler platter, or a clean grate, or thread the pieces on skewers. Cook at high heat, and turn only thick slices. Serve the fruit on its own, beside meat, fish or poultry, or over ice cream or custard.

For grills and broilers in general, see the chapter on dry heat. see chapter 8: Fitting the method to the food

Baking

Most pomes, stone fruits and tropical fruits make good hot desserts when baked. Wash them and peel, core or pit them first. Choose fruit that is ripe but still firm, add sugar or flavorings, wrap it in pastry if the recipe asks, and bake it with no cover in a moderate oven until it is tender or nicely browned. Apples and pears bake especially well whole, because their skin keeps the moisture and flavor in, and once cored they can be filled with sweet or savory stuffings. Mixing fruits balances sweet and sour: try strawberries with rhubarb, or apples with plums.

Several baked desserts are simply fruit with a topping:

• a cobbler has a crust on top;
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• a buckle has a batter.
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Fruit, sometimes poached first, can also be baked inside puff pastry, flaky dough or phyllo for a more elegant dessert.

A clafoutis is a French baked dessert: fruit, by tradition black cherries, laid in a buttered dish under a thick batter like a flan. Made with sliced pears (firm, ripe Anjou) or apples (Granny Smith), it bakes at 375°F for about 1 hour and 15 minutes, until it is firm in the center and lightly golden. For baked apples, Gala apples are cored with a melon baller or knife, leaving the bottom whole so the filling cannot leak out, then filled and baked at 350°F for about 45 to 50 minutes.

Sautéing

A quick sauté in butter and sugar, with spices or liqueur if you like, gives fruit a rich, syrupy taste. Good fruits for it include apples, pears, bananas, pineapples and cherries. Peel, core and seed them as needed, and cut them into even pieces. Melt the fat in a hot pan, add the fruit and any flavorings, and cook fast over high heat. Do not crowd the pan, or the fruit stews in its own juice.

For dessert, the sugar becomes a caramel glaze or syrup, and the fruit fills crêpes or tops sponge cake or ice cream. Liquor may be added and set alight in front of the guests; this is called flambé. For savory dishes, onions, shallots or garlic go in too. Choose the fat to suit the dish; butter and bacon fat are usual.

Bananas Foster is the classic flambé. It was created in 1951 by the chef of Brennan's in New Orleans for a regular named Richard Foster.

• Cook butter, brown sugar and cinnamon in a pan until the sugar melts.
• Add banana liqueur and halved bananas.
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• When the bananas soften and begin to brown, add dark rum, heat it and light it.
• Serve the bananas and sauce over vanilla ice cream.

Sautéing in general is taught in the chapter on dry heat. see chapter 8: Sauté and pan-frying

Deep-frying

Few fruits deep-fry well. Apples, bananas, pears, pineapples and firm peaches do, in or under a batter. Peel, core and seed them and cut them into even slices or chunks. Pat them dry with paper towel if needed so the coating sticks.

A fritter is a small piece of food, such as diced fruit, held together in a thick batter and fried. Frying is so quick that the main ingredient is often cooked first. Drop spoonfuls of the mixture into fat at 350°F (180°C) and let them float free as they fry. They are done when golden brown outside and moist but set inside. Drain them over the fryer, then on paper or a rack, and serve them hot, or keep them under a heat lamp.

Frying and fryer safety are covered in the chapter on dry heat. see chapter 8: How much fat

Poaching

Poaching is one of the most popular ways to cook fruit. It softens the fruit and soaks it with flavor from spices or wine. The liquid may be water, wine, liquor or sugar syrup. Fruit poaches at a low heat, 185°F (85°C), so it softens slowly; the bubbling of hotter liquid would damage it.

• Peel, core and slice the fruit.
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• In a deep, nonreactive pan, mix the liquid with sugar, spices, citrus zest or whatever the recipe asks.
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• Put the fruit in the liquid and lay a circle of parchment paper on top to keep it under.
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• Heat it over medium-high until it boils, then lower the heat at once and let it simmer gently.
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• Cook until a small knife slips in easily. The time depends on the fruit, how ripe it is, and the liquid.

Let the fruit cool in its liquid. Most poaching liquids can be used again, and one with enough sugar can be boiled down into a sauce or glaze for the fruit. Poached fruit is served hot or cold, in tarts and pastries, or beside meat and poultry.

Poaching in general is taught in the chapter on moist heat. see chapter 9: What poaching is

Simmering and stewing

Stewed fruit and compotes are simmered. Fresh, frozen, canned and dried fruit all work. Peel, core, pit and slice the fruit, bring it to a simmer in water, wine or just its own juice, and cook until tender. Add sugar or other sweetening as the recipe says. Serve it warm or chilled: to start a meal, as dessert, or beside meat or poultry.

An apple compote shows the pattern. Small dice of tart apple cook covered over low heat with lemon juice, a little brandy, sugar and cinnamon, stirred now and then, for about 30 minutes, until tender. It is then cooled completely.

Preserving: jams and jellies

Fruit can be kept with sugar if the mixture of fruit and sugar is boiled down until microbes cannot spoil it. The sugar slows microbes but does not kill them.

All fruit contains some pectin, and pectin can set cooked fruit into a soft solid, a gel. A fruit gel needs four things in the right balance: the fruit, sugar, pectin, and an acid, most often lemon juice. Fruit low in pectin, such as strawberries, needs pectin added, either from a high-pectin fruit such as apples or quince, or from a packet. Good-quality fruit that does not look its best is ideal for gels.

How pectin sets is explained in the chapter on what heat does to food. see chapter 7: Gelatin, agar and pectin

Color: pigments, acid and browning

The color of a fruit or vegetable comes from four groups of pigments: carotenoids, chlorophyll, anthoxanthins and anthocyanins. To see what heat and pH do to them, boil vegetables from each pigment group until crisp-tender four ways:

• in plain water with the lid on;
• in plain water with the lid off;
• in water with 1 teaspoon of vinegar (an acid);
• in water with ½ teaspoon of baking soda (a base).

Then compare color and texture, and the color left in the cooking water.

For fruit, the lesson that matters most is texture: acid keeps fruit firm, while baking soda turns it to mush.

Water also moves in and out of fruit and vegetables by osmosis. It flows from where there is more free water to where more of the water is held by dissolved substances, such as salt or sugar. Sugar sprinkled on cut fruit draws out its juice in just this way. To see it at work, keep cucumber slices for one hour in plain water, in salt water, and under dry salt.

Safety for cooked fruit

Any fruit that has been cooked or heat-treated is a potentially hazardous food. So poached fruit, compotes and pie fillings come under the same time and temperature rules as other such foods. The danger zone, where most harmful bacteria grow and multiply, runs from 4 to 60°C (40 to 140°F).

The cooling, holding and storage rules for such foods are in the food safety chapter. see chapter 2: Heat: cooling, holding and reheating