Rate of Fermentation

Rate of Fermentation

Problem set: Plan an investigation to find out what increases the rate

of fermentation.

Scientific knowledge:

Yeast

Yeast is a microorganism which grow by feeding on sugars. In food

manufacture, yeast is used in fermentation and leavening. The fungi

feed on sugars, producing alcohol (ethanol) and carbon dioxide. The

carbon dioxide is used in beer and wine manufacture. In sparkling

wines and beer some of the carbon dioxide is retained in the finished

beverage. The fermentation of wine is initiated by naturally occurring

yeasts present in the grapes. One yeast cell can ferment approximately

its own weight of glucose per hour. Yeast is also used in making

bread. The yeast respires with oxygen by feeding on sugars, breaking

them down into carbon dioxide, water and alcohol (Ethanol). The carbon

dioxide makes the dough rise, the bread is then baked in an oven for

30 minutes. This kills the yeast and evaporates the alcohol. This is

how bread is made.

Fermentation

============

For thousands of years, the process of fermentation has been used to

make bread, beer and wine. Today fermentation is used to make foods

such as bread and yogurt, alcoholic drinks such as wine, drugs such as

penicillin and chemicals such as methanol and citric acid.

Fermentation is a chemical process. Tiny organisms called microbes

grow by converting the sugars in food, such as fruits and grain, into

alcohol and carbon dioxide. Microbes can live almost anywhere. It is

likely that fermentation was discovered by accident when fruits or

grain were stored in containers. One safe and commonly used microbe is

yeast. Not a...

... middle of paper ...

...inge that shows how much

carbon dioxide is produced).

Yeast

Water

Sugar

2 x tripods

Beakers

Gauzes

2 x stop clocks

Method

======

Measure out the amounts of yeast, water and sugar that will be needed

in the experiment. Then fill two beakers half full of water and heat

one of them to 380c and leave the other at room temperature. Put the

two boiling tubes in the beakers of water. Then add the yeast, water

and sugar into the boiling tubes and start the timer. Record how long

it takes for 1ml of carbon dioxide to be produced in each boiling

tube.

=====================================================================

Fair test: I will repeat this test five times to make sure I get

reliable results. I will only change one variable and that will be the

temperature.