Science Help

[Suspective]

Yeah, just need some prompting. Google didn't really say much LOL

Don't have a clue about this question:


Yeast is used in bread-making to make the dough rise. Which of the two temperatures (25oC/30oC) do you think would be better for getting dough to rise? explain your answer.

[Pix]

30oC becuase i think yeasts for bread dough respond to warm water

[Nixt]

30 because that's the ideal temperature for yeast or something

[kk.]

30 degrees. Yeast is an enzyme and enzymes tend to work best at higher temperature

just did a quick search too.

Message:

Most microbes, such as bacteria and yeast, have an optimal
temperature range in which they grow best. If you get either too low or
too high then they grow much slower and finally cease growing at all.
However this temperature range can vary with different organisms.

For example, yeast grows optimally around 30-35 degrees Celsius. If
you get much above 40 it won't grow at all. Below 30 its grow slows
down dramatically and when you get below about 10 it really doesn't
grow much at all. So what causes this?

The main reason is the ability of the enzymes that catalyze all the
biochemical reactions in the yeast cell to function at those
temperatures. Enzymes have an optimal temperature range. When
you get below that range there ability to catalyze the intended reaction
really slows down. Above that temperature and the enzyme begins to
denature or unfold and becomes inactive. Each enzyme will have a
different range where it becomes inactive.

For an organism to stop growing at some temperature, you don't
need all the enzymes to become inactive, you just need for one
essential enzyme to stop working and then the organism fails to
grow. So whichever is the first essential enzyme to get inactivated
defines the maximal temperature at which that organism can grow.

At the lower end it gets more complicated. Usually the enzymes are
not inactivated, but rather just slow down. Eventually you get to a point
where they produce to little of their product to support growth. So
growth of the yeast or bacteria stops for all practical purposes.

Some bacteria for example have become adapted to grow at unusual
temperatures. There are thermophilic bacteria that grow in hot
springs and similar places and grow fine at very hot temperatures.
Some grow at 60-70 degrees Celsius. A few grow above 80 or even
90 degrees Celsius. The enzymes in these microbes have changed
so that they can tolerate the high temperature. But generally these
bugs can not grow at normal temperatures. A microbe that grows
optimally at 65 deg Celsius may be completely unable to grow at 37.

Likewise there are some bacteria which are cold adapted and grow
at very low temperatures but would be unable to grow at our room
temperature. All for the same reasons as I stated.
http://www.madsci.org/posts/archives/jan2001/980908832.Gb.r.html

[MrGazet]

The ideal temperature for yeast growth is 100 to 115 degrees F (38 - 46 C) but for making bread,the ideal temperature is 80 to 95 degrees F (27 - 35 C).
If the yeast grows too quickly, it will produce large bubble pockets in the end product.

At 40 degrees F and below (4 C), it's dormant and doesn't grow at all. If you raise it to 55 (13 C), it will begin to grow - very slowly. But your yeast begins to die at 120 F (49 C), which obviously is not good for either growing a yeast sample for the lab, or for making bread. It dies instantly at 140 degrees F (60 C).

The 30 C (86 F) is just a good temperature zone where yeast likes to grow as it is better control rate for proper leavening.

[Black_Apalachi]

30 degrees. Yeast is an enzyme and enzymes tend to work best at higher temperature ...

This. I think the optimum temperature for an enzyme is between 37°C and 40°C.