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Name: Libbie C.
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: N/A 

PLease could you explain how dough rises and why? Aso why does it rise faster when heated? Another thing that I don't uderstand is how enzymes work. Please help me, Thank-you

The yeast mold consumes sugars present in the bread dough. One of the products of this digestion is CO2, which forms (usually) microscopic bubbles. The CO2 gas occupies a larger volume, but cannot escape the dough because the viscosity of the dough is too high. Hence the dough swells (rises). Other things are going on but the above is the simple answer. Dough rises faster when heated (slightly) because the yeast molds propagate faster when the temperature is somewhat higher than say 25 C. However, if the dough is heated too much the yeast mold is killed and the dough rises less or not at all.

As to how enzymes work. That is a very complicated. Different enzymes work differently. What they have in common is that they accelerate (or retard) the speed at wh ich some chemical reaction occurs, but the specific mechanisms may be complex, and in a lot of cases is not known.

Vince Calder

Dough rises because of production of carbon dioxide, a gas that has no color or taste. When dough contains yeast (a micro-organism) it is the yeast that produces the carbon dioxide while it eats away from the sugars in the dough. Alternatively, the gas can be produced by enzymes and chemicals. This may sound unattractive, but the production of gas by baking powder is completely harmless.

Yeast has a faster metabolism at higher temperatures but would die when it becomes too hot. So by the time your bread is baked it no longer contains alive cells. The chemical processes caused by baking powder are also faster at higher temperatures.

Enzymes are proteins that have a specific function. This can be practically anything. Enzymes can degrade large molecules into small ones (for instance, degrade fat or other proteins: this is how enzymes help destain fabrics in washing powders) or they can build large molecules from small ones (for instance when they build the proteins, DNA, and fats that are constituents of all cells from smaller building blocks). The function of an enzyme is determined by its composition and structure. I hope this information answers your question

Trudy Wassenaar

Dough rises because of the yeast metabolizing the starch (sugar) in the flour. Yeast ferment glucose to alcohol and carbon dioxide. It's the CO2 gas that expands in the dough and causes it to rise. The process is stopped when the oven is turned up. These higher temperatures kill the yeast. When you look at a slice of bread, all the little holes were actually trapped gas bubbles. This process occurs faster at a slightly warm temperature. Enzymes are catalysts that make biochemical reactions occur at a faster rate. These reactions may occur without the enzyme but at rates that are biologically too slow. Enzymes are proteins and they have a unique 3 dimensional shape. Their substrates (the substance they work upon) are also 3 dimensional. They fit together like a "lock and key". Each chemical reaction has its own enzyme.


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