Monday, 3 November 2014

Measuring yeast activity vs temperature

Equipment

Yeast
Sugar (glucose for preference)
Balance
Water
Water bath
Conical flask
bung and delivery tube
water trough
Measuring cylinders
Stopclock

Method

Make up a solution of water and yeast, enough for five experiments (1.5 litre should be sufficient)
Swirl the solution and then measure 200ml into a conical flask.
Add 20g of sugar to the solution in the conical flask and swirl so it dissolves.
Place the conical flask into the water bath set to initial temperature of 20 degrees.
Place in the bung and delivery tube and run the delivery tube into the water trough.
Fill and upend the measuring cylinder over the end of the tube and start the stopclock.
Time how long it takes for 20ml of gas to be produced by the yeast.

Repeat the experiment at a temperature range of 20 degrees to 50 degrees in 5 degree intervals.

Hazards
Water may be spilled so care should be taken and spills mopped up straight away. Any glass breakages should also be cleared up straight away using a dustpan and brush. At the upper end of the temperature range care should be taken when removing the conical flask from the waterbath to make sure it is not too hot to touch and move safely.