The bread recipe I follow says to put it in a preheated oven for 25-35 minutes, or until golden brown. So, basically, you bake it until it’s done – why, then, do I need to preheat?
Peter, Exeter
Let’s not get all pedantic and ask why cookery writers persist with the term “preheat”, rather than plain old “heat”, seeing as that’s all they’re telling you to do, anyway. Instead, we’ll stay on safer(ish) ground and ask why so many recipes start with this instruction in the first place.
As consultant chef Rosie Sykes explains, “It’s the culinary equivalent of hitting the ground running. Some dishes, such as bread and cakes, require an immediate blast of heat, either to push them into action or to make them set as fast as possible.” The same goes for roast meat, which, unless you sear it before (or after) it spends time in the oven, needs some exposure to high temperatures to kickstart both the caramelisation and the Maillard reaction on which so much of its, er, “meaty” flavour relies.
But that’s not the only reason to heat an oven in advance, says Sykes, who earned her kitchen stripes under two giants of modern British cookery, Joyce Molyneaux at the Carved Angel in Dartmouth, Devon, and Shaun Hill at Merchant House in Ludlow, Shropshire. “Other dishes – anything with a pastry base, say, or a souffle – benefit from ‘under heat’ the moment they go in an oven, so when you turn it on, put in a thickish baking tray to warm up.”
Modern ovens heat far more quickly than they used to, and the wait doesn’t have to mean dead oven time or wasted energy, either, says Sykes, whose third book, Roasting Pan Suppers, is out in April. “The high fat content in nuts, for instance, means they burn very easily, and that’s far less likely to happen in an oven as it heats up.” It’s much the same for spices, and for melting or heating butter and fat: “Whatever hits the pan will then start cooking quickly and get a good bit of colour.”
As for the specifics of Peter’s bread, Ben Glazer of Coombeshead Farm in Lewannick, Cornwall, says it’s always a good idea to question baking orthodoxy, “because a lot of the time it turns out to be rubbish”. But Glazer, whose country-style sourdough is quite rightly regarded as the stuff of legend, adds that, in this instance, the logic seems to hold true. “In baking, we look for an ‘oven spring’ [a dramatic doubling in size] that occurs when all the tension created by the shaping, and the CO2 released by the yeast, work in tandem to make a well-leavened loaf with impressive volume.” Put simply, the heat of the oven gives the yeast an final push in its death throes as it releases the last of its carbon dioxide. That’s why you score the loaf, too, because, combined with the heat, it helps release that tension in the dough.
This will all still happen if you baked the loaf from cold, Glazer accepts, but only very sluggishly: “The worry is that, by the time the oven is up to speed, the yeast’s leavening ability and the tension developed in the shaping may both have expired, so you’ll end up with a flat, dry loaf.” The other vital factor is steam. “Steam delays the formation of the crust, which allows the bread to reach its full volume by keeping the outside soft and pliable while the middle expands and bakes.” And you just don’t get steam in a cold oven. (One way around that is to put the dough in in a lidded cast-iron pot, Glazer says, because that in effect turns the pot into a micro-oven where the loaf will prove and bake at the same time, and in which any steam released is conveniently trapped.)
On balance, then, Glazer, who happily self-identifies as a total flour geek, says the benefits of preheating outweigh all other considerations: “At the end of the day, any time, money and energy you think you’re saving by not preheating will be counteracted by the extra time and energy it takes for the loaf to bake.”
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