Читать книгу Bread Matters: The sorry state of modern bread and a definitive guide to baking your own - Andrew Whitley - Страница 67

Protein is important because of its relationship to gluten. The more protein there is in a wheat, the more gluten there will be in a dough made from it.

The terms ‘hard’ and ‘soft’ are often used to differentiate between types of wheat. They reflect the physical character of the grains and have become associated with their baking properties. Hard wheats are generally high in protein and have flinty grains that do not break up easily. Soft wheats are lower in protein, with grains that are plump and quite easily crushed.

Durum wheat, despite the etymological link, is not the same as hard wheat. It is a distinctly different variety of the Triticum species (Triticum turgidum L. var. durum), which is used mainly in pasta manufacture. Durum wheat is high in protein and has the particular quality that its endosperm, the floury material in the middle of the grain, does not immediately reduce to a powder when milled. It holds together in granular lumps called semolina. This can be further milled to a fine flour, but is often used as it comes. Pasta types such as spaghetti and macaroni are extruded – i.e. a stiff dough is forced through nozzles and comes out in the form of tubes. For this process to work, the dough must not be springy or elastic, otherwise it would simply compress in a rubbery mass and block the nozzles. The semolina from durum wheat produces a coherent but not very stretchy dough, which can be extruded and which holds together well afterwards. Rather surprisingly in view of its coarse texture, semolina can also be used to make bread.

The two components of wheat protein that concern the baker are gliadin and glutenin, which together form gluten, the grey-brown web of stretchy material that traps the carbon dioxide gas produced by yeast fermentation and so enables dough to increase in volume. There is an absolute correlation between protein quantity and loaf volume: the higher the flour protein percentage, the greater the potential loaf volume. However, this is where things get a little complicated.

Glutens vary according to their extensibility (how far they will stretch without breaking) and their elasticity (their propensity to spring back when stretched). For most baking purposes, the ideal dough is one that stretches easily, stretches a long way without breaking and doesn’t shrink back. To get maximum volume in a loaf, the gluten matrix must be capable of stretching ever wider (and therefore thinner) without rupturing and letting the fermentation gases escape. Its ability to do this depends partly on the variety and origin of the wheat and partly on the way the baker manages the development of the dough.

As far as the innate properties of the wheat are concerned, hard varieties, often associated with growing conditions in continental climates such as North America, Australia, Ukraine, generally produce ‘strong’ gluten, which holds together well as it stretches, but can be very elastic, with a marked tendency to shrink back. By contrast, the soft wheats of England and France tend to produce gluten that will stretch a long way but can rupture easily and has relatively little elasticity. Flours made from such wheats are often called ‘weak’.

I hope that it is becoming clear that flour quality should not be seen in simple hierarchical terms, as if hard/strong is always better than soft/weak. If this were true, we should presumably not envy France its traditional pain de campagne, nor Italy its focaccia, both examples of flattish breads with an open, holey crumb – the product of precisely the kind of gluten formed from locally adapted varieties of wheat.

Most British flours are milled from blends of UK and imported (often Canadian) wheat and are designed to produce a typically British loaf – very aerated with a close, even texture and, heaven forbid, no holes. However, they may well have too much protein, or too strong and elastic a protein, to produce the best results in open-textured Continental styles of bread. The obvious solution, if you are aiming for authenticity, would be to seek out specialist flours milled abroad, always remembering that you will probably be buying flour milled to a certain style rather than from the wheat of the nation concerned. However, such flours are not widely available, though some British mills do supply their own blends of flour for ciabatta and the like.

One alternative would be to mix a strong flour with a lower-protein ‘plain’ flour or one that does not have the word ‘strong’ in its title. Check on the nutrition information panel to establish the approximate protein percentage. Another possibility is to try flour from a small British watermill or windmill. Often these mill organic wheat and, since they have limited grain storage space, their flour is not usually blended; in other words, it is milled from single batches of wheat, which can often be traced to a specific field on the farm. These small mills almost always use stones for grinding and so preserve the maximum amount of nutrients in the flour, and they are unlikely to throw in any additives such as amylase enzymes. The one drawback (if it is a drawback) of single varieties is their unpredictability: one batch may be superb, another rather less so.

The summers of 1975 and 1976 were warm and dry and the English Maris Widgeon wheat with which I started serious baking was strong and sweet. It was only when we hit the wet harvest of 1977 that I had any real inkling of the pitfalls of using local wheat. Suddenly, my loaves were shrinking in volume and occasionally they even had holes just under the crust. At that time almost all my bread was baked in tins; ciabatta and rustic French styles were a decade away. So the weak, sloppy gluten of those British flours could not be put to good use in holey flat breads. I had to sharpen my skills to ensure that the bread held together.