Eleanor Morris
GCSE Practical coursework
SKILL AREA P: PLANNING
Experiment title
What affect does the length of cooking time have on the vitamin C content of food?
Prediction
I predict that the longer the length of cooking time is, the lower the vitamin C content will be.
To keep it a fair test I am only going to have one variable which will be the length of cooking time. I intend to keep everything else constant. So I shall use the same amount of peas, same temperature and volume of water and allow an equal crushing time of each sample.
Equipment needed
- Bunsen burner, tripod, gauze, heat proof mat
- 1 Litre beaker, 600ml beaker, 10cm3 measuring cylinder
- 50ml beaker, 2cm3 syringe, Pasteur pipette
- Stopwatch, 60 frozen peas (5 for each boiling tube), sand, mortar pestal, ice
- 14 boiling tubes, 2 boiling tube holders
- DCPIP (100cm3) 0.01% concentration, 20 ml of Vitamin C standard
- Safety goggles, lab coat
Method
- Gather all equipment
- Set up water bath
- Take a 1L beaker – fill with 500ml of cold water
- Leave to boil – temp 100oC
- Take 10 uncooked peas and place 5 into tube labelled 0 mins
- Place the remains 50 peas into the boiling water
- From the moment they go in start timing.
- At each time interval (2,4,6,8,10mins) take 10 peas and place them into the 2 corresponding boiling tubes (ie. at 2 mins place 5 peas into both tubes marked 2 mins)
- Place complete tubes in ice beaker.
- Once all cooked and cooling take a tube sample, 10cm3 of water and a pinch of sand – place in mortar pestal. Crush for 1 min.
- Next take 2cm3 syringe and fill with DCPIP, put DCPIP in corresponding boiling tube
- Then take the crushed solution, add drop by drop in DCPIP using Pasteur pipette
- Count amount of drops taken to clear the blue coloured DCPIP
- Record results
- Do for all 6 intervals (0,2,4,6,8,10 mins)
- Repeat the experiment