I'm doing food tech coursework, and I'm really confused on how temperature of water affects the texture of the bread. If someone can answer scientifically that would be great : ) thank you!
The yeast (and other microorganisms) will effect bread dough over time, breaking down sugars and fermenting the dough. The speed and character of how the yeast will work is a function of time and temperature. At colder temperatures, like in the refrigerator, the yeast will work slower and take a longer time to ferment. At warmer temperatures, the yeast will work faster and reproduce more frequently. At hot temperatures (140 F) the yeast will start to die off and be useless.
Therefore, the temperature of the water added to the dough will help determine what temperature the yeast is starting at. Adding colder water is a good way to delay the fermentation process, and warmer water can help speed it up.
Since your question was about texture the question now becomes how does fermentation time effect the texture of my bread? All other things equal, slower fermentation times produces larger and more irregular holes and faster times produce smaller, regular-size holes in the crumb. A fast rising dough will have many small air pockets all of a similar size and shape.
The texture gets affected indirectly by the yeast over activated and ending up overproofed, affecting the oven spring as well. With time, the yeast runs out of food and will break down the starch (to get the sugar portion), not a bad thing in itself if not pushed too far. So the proofing time needs to be adjusted depending on the dough and proofing environment temperatures. Typically more critical in a manufacturing application where the temperature of all ingredients are taken into consideration plus factoring in the heat generated during kneading, the goal being to have exactly a certain temperature when proofing starts, making the following steps timed precisely for consistent results.