Longer, slower fermentation extracts more flavor from your flour. If you are baking a simple white sandwich bread or in a hurry and you just want the darned thing to rise, you can put two or even three teaspoons of yeast into your dough and get the loaf to rise in under an hour. But if you want to create a rustic bread with a rich, nutty flavor, reducing the yeast and allow more and longer rises is appropriate.
Temperature's Impact on Rising
The warmer the temperature, the more active your yeast will be. The more active your yeast is, the quicker the dough rises. Simple enough, but you can use this in a multitude of ways. For example:
- if you want to speed up a rise, turn your oven on for 30 seconds, turn it off, and then place your dough into the slightly-above-room-temperature oven. It should rise noticeably quicker.
- If you need to leave halfway through preparing to bake a loaf, you can throw it into the fridge. It'll continue to rise in there at a much slower pace.
- You can make a large batch of pizza dough and freeze individual pieces of it in freezer bags. The yeast will survive at least a month or two in the freezer. The day before you want to make the pizza, just move it to the fridge to thaw it and then pull it out of the fridge when you want it begin its final rise.
Temperature also has an impact on how your loaf bakes. The general rule is that crusty breads should be baked at as high a temperature as possible. Soft shelled breads should be baked at lower temperatures. When you increase the temperature of your oven your bread bakes quicker (duh).
Professional bakers of rustic breads use ovens that achieve higher temperatures than home ovens achieve. Turning the temperature of your oven up when baking rustic breads will help you get closer to professional quality loaves. Buying a pizza or baking stone is another inexpensive method of capturing more heat in your oven and improving the quality of your bread (I have shattered two of these, so I don't currently bake with one. I'll probably end up getting another one some day, but I can't say the quality of my bread has suffered that much without one).
If you get really serious about bread baking, there is even a movement of bread hobbyest who build large hearth ovens in their backyards to reproduce professional quality loaves. Pick up a copy of "The Bread Builders" if this interests you.
My wife is pleased that I have not gotten that crazy about baking good bread at home (yet).
Time and Temperature Together
As you can see, time and temperature work in opposition to one another during dough formation: increase the temperature, decrease the time that your loaf rises; decrease the temperature, increase the time it takes to get to full size.
In the rising stage, if you are striving to extract the maximum flavor from your flour, you want to slow the rise down. If you want a make a quick loaf in time for dinner, speed the rise up.
While baking, If you want a crusty bread, you'll want to increase the temperature of the oven and reduce the amount of time your loaf bakes. For soft, pillowy breads, do the opposite (more time at a lower temperature). There are times when either technique is appropriate, so don't be worried that you aren't doing things the "right" way!