A look at different baking techniques, explaining the way in which ingredients react when placed in a dry heat.
Baking techniques improved from their simple beginnings as people discovered the beneficial effects of fermentation. At first, early bakers probably observed that the gruels and doughs they made became puffy when left standing for a while. Although they did not know the cause of this was due to yeast bacteria that entered the grain mixtures from the ambient air, they did recognize the puffiness obviously increased the volume of their products and the puffy products had enhanced taste. Experimenting with a variety of grains down through the centuries revealed that most grains can ferment, but that wheat flour produced the best light, porous textured dough. When wheat's proteins, collectively called gluten, combine with water in the proper proportions, an elastic dough is formed that can trap gas and maintain the spongy structure when baked.
The Egyptians are recognized as being the first bakers to intentionally use leavening to make bread. By 2600 BC they were mixing flour, water and salt and inoculating the mixture with a sour dough starter, then adding ingredients like poppy seeds and sesame seeds for flavor. They also created the first ovens which they built with Nile clay. These cylindrical structures were tapered into a cone shape at the top. Inside, a horizontal partition divided the firebox from the baking area where the dough was placed. Baking technology advanced quickly during the Industrial Revolution of the mid nineteenth century as a vast array of baking utensils and equipment were developed and marketed. Many manual baking processes gave way to automation and that trend continues to the present. Also, over time, the quality and variety of baking ingredients have greatly improved.
The ingredients basic to most bakery products are flour, water and leavening agents. Other common ingredients include milk, eggs, shortening, salt and sweeteners, which add nutritional value, enhance flavor and alter texture. Bakers use high protein, hard wheat flour primarily for breads, rolls, crackers, and other foods that need an elastic dough. About one percent of regular wheat flour is composed of various sugars including fructose, glucose, maltose and sucrose, most of which are fermentable by baker's yeast (Saccharomyces cerevisiae)
In order to begin the fermenting process, baker's yeast is dissolved in water, then this solution is combined with flour. The yeast metabolizes the sugars in the flour and whatever other sugars, if any, have been added to the dough. Bubbles of carbon dioxide gas released during fermentation act as the actual leavening agent as they push against the flour mixture, forming cells that expand it. Baking heat vaporizes the liquids in the dough, creating steam which causes more expansion, and finally, the heat dries the product to a point at which it firmly holds its structure. Yeasted products tend to be nutritionally better that products that use chemical leavenings because the yeast cells actually contribute a large assortment of if vitamins and good quality protein.
Low protein, soft wheat flour is used mostly for cakes, cookies, quick breads, scones, biscuits, muffins, and other products that have crumbly, soft, dense textures. These types of foods are leavened by carbon dioxide bubbles that develop from the reactions of chemicals like baking soda (sodium bicarbonate). Used alone, baking soda can turn dough alkaline causing discoloration and loss of flavor and a slowing of carbon dioxide release. Adding an acidic substance like cream of tartar (potassium acid tartrate), calcium phosphate, or sour milk to baking soda promotes gas bubble generation and slight acidity of the batter, which enhances flavor. For reliability and convenience, many home and commercial bakers use in their batters a ready made, appropriate mixture of baking soda and acids called baking powder, which produces carbon dioxide bubbles and a few tasteless, harmless salts. Eggs, sweeteners, milk, oils, nuts, fruits and flavorings like vanilla and chocolate are often added to these bakery items to add nutritional value and flavor and improve texture.
Sponge cakes, angel food cakes and other similar delicately flavored treats rely on air or steam for their expansion. Egg whites contain protein loaded albumen that foams readily, entrapping tiny air bubbles, when the whites are vigorously whipped. In order to keep the air bubbles suspended in the foam, it needs to be gently folded, rather than briskly mixed into a batter. Bakers need to avoid letting any kind of oily substance contact meringues and other protein based foams because any amount of oil will interfere with air bubble expansion. Puff pastry is prepared by layering and rolling fat with the dough, then it is baked, initially, at a high temperature that causes puffing. The pastry's volume expands as much as ten times the original dough because of the huge increase in water vapor pressure where the fat layers meet the dough. Lowering the temperature for the remaining baking time allows the dough to completely dry, yielding flaky, crisp outer layers. Cream puffs are made from chou paste which comes from beating together flour, butter, salt and boiling water. Small spoonfuls of the dough are then baked like puff pastry, at high, then lowered temperatures, on sheets. The air bubbles rapidly expand, causing the inside to be quite hollow. Once cooled, these puffs can be filled with tasty fillings.
Pie crusts usually are unleavened. Their flakiness depends on the type of fat used and minimal kneading and rolling of the dough. For easy handling of the dough, fats should be solid at room temperature, so oils do not work well in pie crusts.
Of all the liquids used in baked goods, water is the one most commonly added to doughs. Water enables the gluten in flour to help create dough's spongy structure. Baker's yeast needs to dissolve in water so that it can begin to metabolize the sugars in the other ingredients and thus release carbon dioxide for leavening. Baking powder requires water to begin the chemical reaction that releases carbon dioxide. Water that is too soft can make a dough sticky. Very hard water may slow dough expansion by toughening the gluten, and alkaline water can impede fermentation. The best water for baking should be of a medium hardness with a neutral pH or slightly acid.
Many factors influence baking, so following some general guidelines will promote a successful outcome. Ingredients for baked foods should be of good, fresh quality, accurately measured, used in proper proportions and at correct temperatures, and they should be mixed according to the recipe. Utensils should be sturdy and clean and the size and shape recommended in recipes. The oven needs to be able to hold a proper, constant temperature and should be level so that the baked foods do not come out uneven.
Opening the oven door frequently will lower the temperature below what is proper and will waste energy. Some baked goods require a pre-heated oven before they are put in to cook. About ten minutes of preheating at the proper temperature is usually sufficient. Casseroles and convenience foods can be started in a cold oven. Baked goods cook best when they are positioned in the center of the oven rack. For even heat circulation, multiple items being baked at the same time should be staggered on the racks and not crowded, and pans should be placed no closer than one inch from the oven side walls.
Discovering the cause of baking mistakes can help prevent repeating them the next time. Cakes and quick breads that peak at the center or crack at the top may have been put in an oven that was too hot at first, or they were over-baked or put in too small a pan. Too little or too much flour can cause this same problem, as can over-mixing. If a cake falls, the oven may not have been hot enough, the door may have been opened too much to check on baking progress, letting out the heat and so changing the temperature, or it may not have been baked long enough. Too much or too little liquid or sweetener may have been added. Baked goods can stick to their pans if they are left to cool in them too long. They can crack and fall apart if they are removed from the pan too soon. Too much shortening, sweetener or leavening can also make them fall and crumble. Doughs may not rise well if they are not kneaded long enough. Cakes may not rise if they are over mixed.
Following basic baking principles and using well tested baking recipes will help any cook create delicious baked goods.
