A number of factors can affect the rate at which an enzyme works for example these can be concentration, temperature and the ph.
The PH levels can affect the rate at which the enzyme works, if the level is too acidic or alkaline the 3D shape of the enzyme is altered because the conditions are too corrosive for it to keep its shape. This then means the enzyme is denatured and can no longer carry out its specific function. Since the shape of the enzyme is altered it can no longer react with the substrate. I wish to investigate how changing the concentration of pectinase affects the production of fruit juice, in this case its apple pulp and apple juice that will be produced. I have carried out one preliminary experiment to help me decide which concentration of pectinase to use and how much juice is produced.
My hypothesis is that the higher the concentrate of pectinase added to the pulp the more juice will be produced. The pectinase with the highest concentration will produce the most juice and in the same amount of time. I will give all 5 of my solutions the same amount of time (10 minutes), and record the time.
Equipment List:
- 5 different concentrates of pectinase enzyme
- 5 pieces of filter paper
- 5 funnels
- 5 measuring cylinders
- 1 stop clocks
- 5 syringes
- Apple pulp
- Water bath
- 5 beakers
- 1 thermometer
I put 50g of apple pulp into each of five beakers and I numbered each beaker 1 to 5.
I then added 5cm³ of pectinase however not of only one concentrate of pectinase. I did the following:
- I didn’t add anything to the first beaker because it is meant to have o% of pectinase concentrate.
- I added 5cm³ of 0.1% of pectinase to the second beaker
- I then added 5cm³ of pectinase to the third beaker this time using 0.10% of pectinase.
- I added 5cm³ of 0.25% of pectinase to the third beaker.
- Lastly I added 0.50% of pectinase concentrate to the least beaker.
I did this to all 5 beakers and I then used a plastic spoon to mix the pulp and pectinase together. I then incubated the 5 beakers in the water bath with a temperature of 40ºC and for 15 minutes. After this I took out the 5 beakers and placed them over filter paper and over a funnel, which was under a measuring cylinder. I left the mixture to filter through on its own for 10 minutes. I used my stop clock to measure all the times, when I saw the 10 minutes was up I removed the filter paper with the left over pulp in it and I put it in a brown bin. I then recorded my results in this table:
The results of this preliminary experiment show that 0.50% concentration of Pectinase, ‘working enzyme’, worked most effectively. It produced the most apple juice from the pulp. However, the lower concentrations of 0.25% also worked well and so did the 0.10 %. The 0.50% pectinase produced the most juice as I predicted. It produced this in the same amount of time as the rest.
There are certain things that must be kept constant in order for my test to be fair. In order ensure the accuracy of my results I must make sure that only the independent variable changes (the concentrate of pectinase) and that everything else stays exactly the same. Therefore I must make sure that the same amount of apple pulp is put into each beaker.
Also all the beakers are incubated at the same temperature for the same period of time.
The same amount of pectinase is added to the apple pulp each time (5cm³).
To make sure I have accurate results I must use the equipment as accurately as possible. For example, when weighing out the 50g of apple pulp I should place the beaker onto the scales first, and then press the ‘tear’ button to return the measurement to nought and then add the apple etc.
