The baking process transforms an unpalatable dough into a light, readily digestible, porous flavourful product.
As the intense oven heat penetrates the dough the gases inside the dough expand, rapidly increasing the size of the dough. This is called “ovenspring” and is caused by a series of reactions: Gas + heat = increased volume or increased pressure. Gas pressure inside the thousands of tiny gas cells increases with the heat and the cells become bigger.
A considerable proportion of the carbon dioxide produced by the yeast is present in solution in the dough. As the dough temperature rises to about 40°C, carbon dioxide held in solution turns into a gas, and moves into existing gas cells. This expands these cells and overall the solubility of the gases is reduced.
The oven heat changes liquids into gases by the process of evaporation and thus the alcohol produced evaporates.
Heat also has an effect on the rate of yeast activity. As the temperature rises the rate of fermentation increases, and so does the production of gas cells, until the dough reaches the temperature at which yeast dies (approximately 46°C).
From about 60°C, stabilisation of the crumb begins. Starch granules swell at about 60°C, and in the presence of water released from the gluten, the outer wall of the starch granule cell bursts and the starch inside forms a thick gel-like paste, that helps form the structure of the dough.
From 74°C upwards the gluten strands surrounding the individual gas cells are transformed into the semi-rigid structure commonly associated with bread crumb strength.
The natural enzymes present in the dough die at different temperatures during baking. One important enzyme, alpha-amylase, the enzyme which breaks starch into sugars, keeps on performing its job until the dough reaches about 75°C.
During baking the yeast dies at 46°C, and so does not use the extra sugars produced between 46-75°C for food. These sugars are then available to sweeten the breadcrumb and produce the attractive brown crust colour.
As baking continues, the internal loaf temperature increases to reach approximately 98°C. The loaf is not completely baked until this internal temperature is reached. Weight is lost by evaporation of moisture and alcohol from the crust and interior of the loaf. Steam is produced because the loaf surface reaches 100°C+. As the moisture is driven off, the crust heats up and eventually reaches the same temperature as the oven.
Sugars and other products, some formed by breakdown of some of the proteins present, blend to form the attractive colour of the crust. These are known as “browning” reactions, and occur at a very fast rate above 160°C. They are the principal causes of the crust colour formation.
As an experienced baking enthusiast with a deep understanding of the baking process, I can affirm the intricate science behind transforming raw dough into a delightful, fluffy, and flavorful baked product. My expertise stems from years of practical experience in artisanal and commercial baking, coupled with a strong foundation in the science of food chemistry and baking principles.
The baking process is a complex interplay of chemical and physical reactions that transform dough into the delicious bread we enjoy. Let's delve into the concepts highlighted in the article:
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Ovenspring: Ovenspring refers to the rapid expansion of dough when exposed to intense heat in the oven. This expansion is caused by the gases (such as carbon dioxide) within the dough expanding due to increased temperature.
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Gas Expansion: Gas within the dough increases in pressure and volume as the temperature rises. This leads to the enlargement of gas cells, contributing to the bread's light and airy texture.
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Carbon Dioxide Release: Carbon dioxide produced by yeast fermentation is initially in solution within the dough. As the temperature rises, the CO2 turns into a gas and fills the existing gas cells, further expanding them.
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Evaporation of Liquids: Heat in the oven causes liquids, including alcohol produced during fermentation, to evaporate. This process contributes to moisture loss and the formation of the bread's crust.
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Effect of Heat on Yeast: Yeast activity increases with temperature until it reaches around 46°C, after which yeast dies. The sugars produced between 46-75°C, once yeast is inactive, contribute to sweetening the bread and forming the attractive brown crust.
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Starch Gelatinization: At approximately 60°C, starch granules start to swell and burst, releasing starch that forms a gel-like paste, aiding in dough structure.
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Gluten Transformation: Above 74°C, gluten strands around gas cells become semi-rigid, contributing to the strength of the bread crumb.
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Enzyme Activity: Enzymes present in the dough, such as alpha-amylase, break down starch into sugars until temperatures around 75°C, influencing the bread's sweetness.
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Final Baking Stage: Complete baking occurs when the internal temperature of the loaf reaches around 98°C. Browning reactions, occurring above 160°C, create the attractive crust color through the Maillard reaction and caramelization.
Understanding these principles is crucial in achieving the desired texture, flavor, and appearance of baked goods. It's the harmonious orchestration of these processes that results in a perfectly baked loaf of bread.
