the effcet of tempreture on the activity of the enzyme lipases

what is a lipid

an enzyme that catalyses the breakdown of fat in milk to produce fatty acids

how does the pH get to 10 - alkaline

mixture: milk, lipase and sodium carbonate solution

how does the pH drop

lipase catalyse, after acids form

what is phenolphthalein

an indicator which is pink in the alkaline solution but goes colourless when the ph drops below 8.2

how is phenolphthalein useful

to measure how long it takes for the pH to drop bellow 8.2 at different temperatures

hypothesis

the higher the temperature the faster the reaction until the optimum temperature is reached when the rate will decrease

hazard

phenolphthalein solution is an irritant and is highly flammable

risk/precautions

• wear gloves

• keep solution away from fire

variables - independent

tempreture

variables - dependent

time taken for enough acid to form, so that pH drops 8.2

control variables

• volume of milk

• volume and concentration of sodium carbonate solution

• volume and concentration of lipid solution

• rate of stirring

equipment

• water baths at different temperature

• 2cm3 syringes

• 10cm3 measuring cylinder

• 10 test rubes

• thermometers

• stirring rod

• stop watch

solutions

• milk

• sodium carbonate

• lipase

• phenolphthalein

method

1. water baths of 20, 30, 40, 50, 60 c

2. place test tube of lipase solution in each water bath

3. each test tube add 4 droplets of phenolphthalein indicator

4. using a clilinder measure out 5cm of milk and than add it to the tube with the indicator

5. using a clilinder measure out 8cm of sodium carbonate solution and add it to the test tube, turn pink because its an alkaline

6. put thermometer in the test tube and place it in the water bath at 20

7. when temp reaches 20 remove the thermometer from the test tube and use 1cm of lipase solution from the 20c water bath

8. start the stop watch

9. stir the contents with a rod until the solution turns colourless

10. stop re peat 3to10 for each temperature

11. reapeat 3 more times

alternatives

• protein of egg albmen which is denatured by strong acids/alkelines/high temps which causes to solidify and become opaque

• hydrogen peroxide solution