Investigating the Effect of Enzyme Concentration on Pectinase in the Production of Fruit Juice(Biology)

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Investigating the Effect of Enzyme Concentration on Pectinase in the Production of Fruit Juice

In this practical, I shall demonstrate the relationship between the concentration of pectinase and the amount of fruit juice produced accordingly in proportion.



Pectinase solution

10 x filter paper

Knife or kitchen mincer

Glass rod

Water bath X 1

250 ml beakers X 2

Wash bottle of distilled water

100 cm^3 measuring cylinders

In the case of the pectinase, the concentration had to be divided into sufficient amounts from which I can gain sufficiently accurate results to picture any relations between the concentration of the enzyme solution and the apple juice produced.

However, there is a problem in this case. Due to laboratory limitations, only a set amount of pectinase solution is available.

To eliminate the problem, different concentrations of pectinase will be made by addition of sufficient amount of water to make test tube of pectinase sample of different concentration. To do this, a set amount of Pectinase + water must be decided i.e. a sufficient volume which can be appropriate for accurate measuring of production of apple juice and also sufficient resourcefully. (Also, the squashed apple should be fully inside the pectinase solution)

These will be made by using the syringes to collect the pectinase and water. They will then be put in test tubes, which will be slightly shaken to make the solution mixed equally.


There are two possible results attainable from the experiment.

Null Hypothesis: There is NO effect of concentration difference of pectinase solution in the production of fruit juice.

Alternative Hypothesis: Concentration difference has an effect in the production of fruit juice i.e. the more concentrated, the more rapidly the fruit juice is produced. (I.e. greater volume of fruit juice)

The more likely however, based on scientific evidence, is the alternative hypothesis I.e. the higher the concentration, the more fruit juice produced.

The scientific evidence we can obtain to make this hypothesis is the enzyme ‘Lock and Fit’ model and the induced fit model:

‘Lock and Fit’ Induced fit


Although scientifically, the ‘induced fit’ model shows a clearer description of how enzymes catalyses substrates, for the purpose of this experiment which is to show the quantities result of the fruit juice produced according to the concentration, we need not to make such distinction.

In context of this experiment, we can see that the more active site available to break down the substances (apple), the more fruit juice that is produced in a set amount of time. This automatically corresponds to the number of enzymes that will be available to break down the substrate, meaning the more enzymes available, the higher the yield of fruit juice. Since higher concentrations indicate more enzymes available to break down the enzymes, we can make the hypothesis that the higher the concentration of the enzyme solution, the greater the yield of fruit juice.

Variable control

For this experiment to be fair, it is crucial for me to point out the control variables and set them to such for each experiment.

1). pH

pH is an important factor to take into account. This is because some enzymes each have different optimum pH for maximum
catabolism/anabolism (catabolism in this case).

It is therefore because of this fact that I have to acknowledge the pH I will use for each of the experiment. I.e. for each different concentration used, all of the test tubes containing the pectinase solution must have equal pH value. This will be checked thoroughly by checking the pH of enzyme solution before starting.

2). Temperature

Like pH, Temperature also increases enzyme activity by increasing the kinetic energy within the molecules i.e. faster reactions or...
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