What is yeast and how does it cause bread to rise?

Answer 1

A micro-organism. Yeast consumes sugar and expels Co2 and alcohol as byproducts. Unlike beer, In bread the alcohol evaporates. The yeast reproduces in the warm dough, and the Co2 gas expands to make it puff up.

Answer 2

Yeast is a microorganism with several very cool characteristics. First of all, it's not a plant OR an animal -- it's a mycobacterium, in the same kingdom as molds and fungi. Remember that the next time you're playing "20 questions" and somebody asks if it's animal or vegetable. :-)

This question comes at the perfect time for me, though, because I just put a tray of homemade cinnamon rolls in the oven, right next to a loaf of homemade bread that's almost done. When we started making the bread, we poured the package of yeast into a bowl of warm water with a little sugar dissolved in it. Why? The yeast cells are dormant when they're in the fridge, and you need to "wake them up" before baking. To do this, you warm them (not in hot water, but water about body temperature is fine) and give them a nice snack -- in this case, some sugar.

After a few minutes the yeast should start to "bloom" -- meaning it'll foam up a bit. The whole process is called "proofing" the yeast, because it's proof that the yeast is still good. We then added the yeast and water to the flour, shortening and other ingredients that are going into our bread; we stirred it up, my son rolled it out, and we put it back into a bowl to rise.

When this happens, the yeast cells are eating some of the starches and sugars in the flour, and also "breathing." Just as humans, cats and snakes do, yeast cells exhale carbon dioxide (CO2). So while the bread is rising, the yeast cells are pumping out CO2; the bread rises because the water has dissolved a substance called gluten in the flour, which is stretchy.

When we bake the bread, the starch in the flour sets up and our friends, the yeast cells, are sadly killed, but we will appreciate the wonderful work they do as soon as dinner's ready. :-)

Answer 3

Yeast is the ingredient that makes bread rise. It is a fungus that feeds on sugar. Yeast produces alcohol and carbon dioxide. Carbon dioxide is the gas that makes the bread rise.

Cooking will destroy the alcohol and the yeast. The bubbles are left behind and that is what makes bread soft.

Answer 4

Yeast is a single-celled fungus that feeds off the sugar that you add to breads when making them. It's waste product is carbon dioxide. The carbon dioxide bubbles try to rise, but get trapped in the sticky bread dough. This makes the bread rise because it's filling up with gas.

Answer 5

Simply put: Yeast is a micro organism (plant) It causes bread to rise through a fermentation process and the rising is the carbon dioxide bubbles in the dough from its respiration.

Answer 6

Yeast is a one celled plant that eats sugar and farts CO2 gas. When you add it to a mixture of flour and water it starts eating and producing gas bubbles. The gas bubbles blow little holes in the dough and make it rise up. Eventually the risen dough goes into the oven where the heat kills the yeast and puffs up the bubbles to raise it and make the holes you see in bread.

Answer 7

yeast is a mixture that makes bread rise how it just does

Answer 8

yeast grows there for making the bread grow

Answer 9

It is a fungi, here is the site that will tell you all


http://en.wikipedia.org/wiki/Yeast

Answer 10

yeast is a bacteria that reacts to heat?