When yeast is dissolved in water that is too hot, it can have several negative effects on the fermentation process. First and foremost, if the water temperature is 130 degrees Fahrenheit or above, it can kill the yeast entirely. This means that the yeast will not be able to produce any carbon dioxide gas, which is essential for the dough to rise during the fermentation process.
Additionally, even if the yeast is not completely killed, hot water can cause the yeast to work too quickly. This rapid fermentation can result in a sour flavor in the bread and cause it to rise less than desired. The yeast needs time to properly ferment and develop flavor, and when exposed to high temperatures, this process is rushed.
I have personally experienced the negative effects of using water that is too hot when working with yeast. On one occasion, I was attempting to make a loaf of bread and absentmindedly used water that was too hot to dissolve the yeast. As a result, the dough did not rise at all and had a dense texture. The bread also had a slightly sour taste, which was not pleasant.
To prevent this from happening, it is crucial to ensure that the water used to dissolve yeast is at an appropriate temperature. The ideal range is typically between 100-110 degrees Fahrenheit. This allows the yeast to activate and ferment properly without being killed or working too quickly.
Using water that is too hot when dissolving yeast can have detrimental effects on the fermentation process. The yeast may be killed, resulting in no carbon dioxide production and no rise in the dough. Alternatively, if the yeast is not killed, the hot water can cause the yeast to work too quickly, leading to a sour flavor and reduced rising. It is important to be mindful of the water temperature to ensure successful fermentation and optimal bread quality.