Control - To keep the experiment fair and ensure that the results are accurate, the following factors need to be kept the same:
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pH – Different enzymes work better in different pH conditions as they have their optimum pH which allows them to react at different rates. Excessive alkalinity and acidity may also denature enzymes so keeping a constant pH will make sure that this will not happen.
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Temperature – Different enzymes work better in different temperatures as they have their optimum temperatures that allow them to react at different rates. Extreme temperatures may also denature enzymes or slow down the reaction, so keeping a constant temperature will ensure that this will not happen.
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Volume of Pectinase – this is important to keep constant because it ensures that the results are fair, as different volumes of Pectinase will give the same mass of apples more or less to react with, and thus giving inaccurate results for the purposes of the experiment.
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Amount of Apple - If the amount of apple is not kept the same, the amount of pectin available to react with the same amount of Pectinase will vary and the results may be affected not because of the concentration which will defeat the purpose of this experiment.
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Surface Area of Apple – the surface area of apples also affect the outcome of apple juice because if surface area increases, there are more pectin exposed for the Pectinase to react with. So by using a grater (included in the apparatus), the size/shape of the apples will be kept as similar as possible.
Apparatus:
Appropriate apparatus needs to be used so fewer errors will be made also measuring equipment should be regularly check so the results will be as accurate as possible. However, there will be inevitable errors with data collection as measuring equipments, such as the measuring cylinder, which has uncertain degrees of accuracies and should be taken into account when processing the data.
Goggles* Labels Beakers Pectinase Concentrates (1,2,3,4,5%) Apples
Peeler, Knife and tile Grater Scale Measuring Cylinders pH 7 buffer Stopwatch Glass rod Water Bath (50°C) Funnel Muslin cloth
[*Goggles should be worn at all times during the process of the experiment]
Method:
- Gather apparatus and label the beakers with the different Pectinase concentrations
- Peel the apple and grate 50g into each beaker. (remove excess apple juice that is produced)
- Measure 20ml of pH 7 buffer and 30ml of concentration
- Pour liquids into appropriate beaker and start timing. Stir for 30seconds with glass rod
- Place the beaker in the water bath for 10 minutes
- Filter the juice from each beaker into measuring cylinders with funnel and Muslin cloth. Then remove Muslin cloth and funnel with the apple pulp after 2 minutes. Record amount of Apple Juice produced in table as seen in fig. 1.
- Repeat 3-6 with different concentrations
Fig 1.
Results
Fig 2.
As seen in fig 2., the average volume of apple juice was used to plot the graph to illustrate the trends of the results. The error bars used also display the degree of accuracy and uncertainty of which the results can range in. The pattern demonstrates a positive correlation which shows that the volume of apple juice is proportionally increasing with the Pectinase concentrations. Except for one result which may be an anomaly, indicated in the color yellow in fig 2. The Pectinase concentration of 4% has been shown to not fit the trend as the volume has fallen to 51.6 ml which lower than of Pectinase concentration of 3% of 52.6% which should not have happened. The reasons of the results will be discussed in the Analysis and Evaluation shown below.
Analysis and Evaluation
The average volume of apple juice used to plot the graph was proven appropriate as the results were satisfactory, because it clearly shows the overall trend that was occurring supporting the hypothesis of an increase in apple juice in relation to Pectinase concentration.
The best fit curve used to make the emphasize and highlight the trend that was occurring shows that as it reaches Pectinase concentration of 4%, the volume of apple juice produced does not increase as rapidly as seen between concentrations 1 to 3%. This may be because, as mentioned in the hypothesis, there are so many active sites in the Pectinase to react with the pectin in the cell wall of the apple and therefore the production of apple juice is slowed down. However, there isn’t a wide enough range of Pectinase concentration to confirm this and the amount of apple juice produced is only decreasing not completely stopping which means that the hypothesis is not entirely correct.
One anomaly was found in the results as highlighted in yellow in fig 1. and in yellow in fig 2. This may be because there were many other factors that were unavoidable such as human errors, time constraints and insufficient skills in measuring as well as the degree of accuracy of the equipment.
Conclusion
Overall, the experiment was quite successful as only one anomaly was found in trial 3 which caused the results to be inaccurate. The causes of it was understood and could be avoided next time if it were to be repeated and enabled a improvement and proved as a positive effect. The anomaly did not have a great impact on the results as well because the overall trend of the graph did support the hypothesis and if the anomaly did not occur it could have been quite accurate. To improve on this experiment however, some of the errors mentioned should be avoided so that the results would be even more accurate. Some errors are also more easily avoided than others and therefore more manageable but other errors such as time constraints would require more preparation and human errors would be more difficult to control so these errors may be exempted. Another improvement can be to increase the range of concentrations used so that the accuracy of the hypothesis can be further dis/proven. One last additional suggestion can be to record the rate of reaction as well which means the amount of apple produced can be taken out to measure in time intervals and would give a greater variety of results to analyze.
Tisha Yap 6C2
