Yeast And Making Beer

Question 0

After the sugar is out the grain, the yeast is added and the mixture is incubated (warmed up). The yeast ferments the sugar into alcohol. The fermenting vessels are disingenuous to stop unwanted Microorganisms and air getting in. Describe this SECOND stage… (2)

Answer 0

1. ) increasing concentration of alcohol in fermentation mixture due to anaerobic respiration eventually started to kill the yeast. As yeast dies, fermentation slows down.
2. ) different species of yeast can tolerate different levels if alcohol. Some species produce strong beer with a high concentration of alcohol.

Question 1

We use yeast for brewing beer. Firstly you have to go the sugar out the grain. How do you get the sugar out the grain? (3 steps!)

Answer 1

1. ) barley grain germinate for a few days. Starch is broken down into sugar by enzymes. Grains are died in a kiln (malting).
2. ) malted grain is mashed up and water is added to produce a sugary solution with lots if bits in it. This is sieved.
3. ) hops are added to give the beer it’s bitter flavour:

Question 2

What happens after the yeast is added? (3rd stage)

Answer 2

The beer is drawn off through a tap. Sometimes chemicals called clarifying agents are added to remove particles and make it clearer.

Question 3

What happens after the beer is drawn off? (4th and FINAL stage)

Answer 3

Beer is pasteurised.

Question 4

The respiration rate of yeast depends on it’s conditions. You can do experiments to investigate….

Answer 4

How the rate if co2 production by yeast changes under different conditions.

Question 5

How do you measure the effect of changing temperature? (6 steps)

Answer 5

1. ) mix: sugar, yeast and distilled water
2. ) attach bung with tube leading to a second test tube if water.
3. ) place tube containing yeast mixture in a water bath at a certain temperature.
4. ) warm tube up then count bubbles produced in a period of time. (Used to calculate rate of CO2 production)
5. ) repeat experiment with water bath set at different temperatures.
6. ) respiration is controlled by enzymes - as temperature increases rate of respiration increases.