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Effect of temperature on the enzyme pectinase in fruit juice production.

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Effect of temperature on the enzyme pectinase in fruit juice production AIM: To investigate the effect of temperature on the work of the enzyme pectinase in fruit juice production. INTRODUCTION It is stated that temperature has an effect on Enzymes. I am going to investigate this fact using my chosen enzyme Pectinase. This enzyme is used in the fruit juice industry and I am going to use this enzyme to explore the question: How Does Temperature Affect Enzymes? BACKGROUND INFORMATION Enzymes are biological catalysts that speed up the rate of a reaction without being changed or used up in any way. They are protein molecules that are tailored to recognize and bind specific reactants and speed their conversion into products. These proteins are responsible for increasing the rates of all of the many thousand of reaction taking place inside cells. Activation energy is the energy barrier over which the molecules in a system must be raised for a reaction to take place. The use of enzymes lowers the activation energy so the reaction can proceed at a faster rate. ( GRAPH TAKEN FROM REFERENCE 7) A number of factors affect the activity of enzymes in speeding conversion of reactants to products. These factors are; 1. PH: Each enzyme has an optimal pH range that help maintain its normal configuration in an environment which it operates. The tertiary structure of a protein depends on interactions such as hydrogen bonding, between R groups. A change in pH can alter the ionization of these side chains and disrupt the normal configuration and in some case denature the enzyme. A denatured protein can not combine with a substrate. 2. SUBSTRATE CONCENTRATION: At very low substrate concentration, collisions between enzyme and substrate molecules are less frequent and the reaction proceeds slowly. As the substrate concentration increases, there reaction rate initially increases proportionately as collisions between enzyme molecules and reactants become more frequent until further increases in substrate concentration have no effect on there reaction rate. ...read more.


For the 0 degrees temperature, ice water was used instead using the same procedure. DIAGRAM OF APPARATUS SAFETY/RISK ASSESSMENT I did not carry out a risk assessment as I am not using any chemicals or hazardous substances. My chosen apparatus is safe so there are no major concerns. Nevertheless I am still going work as safe as I can. * Safety goggles must be worn throughout. * A lab coat must be worn throughout the experiment. * Hands must be dried when operating the water baths. * The juice produced must not be tasted as this might not be suitable for consumption. It's better to be safe than sorry. RELIABILITY Reliability is the amount of confidence that can be placed in the set of observations .To ensure that the results are reliable; some factors must be kept constant throughout the experiment. These factors are Amount and Concentration of Pectinase- kept constant for all experiment and has to be measured accurately for a fair test. Amount of fruit- This also needs to be kept constant throughout. The same type of apparatus needs to be used throughout. The experiment was carried out twice to enable an average to be taken. I used a range of nine temperatures for better comparison of results. These were at 10 degree intervals to include extreme and intermediate temperatures. RESULTS The following results were obtained. Table showing amount of juice produced at different temperatures. Temperature (Degrees) 1. Juice produced/10 minutes in ml 2. Juice produced/10 minutes in ml (REPLICATE) Average juice produced/10 minutes in ml Average juice produced/minute. In ml 0 0 0 0 0 10 3.5 3.7 3.6 0.36 20 7.0 7.1 7.05 0.705 30 9.6 9.4 9.5 0.95 40 9.8 9.8 9.8 0.98 50 5.2 5.0 5.1 0.51 60 3.2 3.3 3.25 0.325 70 2.4 2.8 2.6 0.26 80 1.2 1.3 1.25 0.125 Looking at the table I can see the trend that I had already predicted. ...read more.


This would give a better indication of the effect of temperature on Pectinase. 8. The experiment should be conducted over a longer temperature range and at more intervals, like 5 degrees instead of 10. This would greatly improve the accuracy of my results and more results would be obtained for a better graph. CONCLUSION Because of the several sources of errors and limitations of the techniques used, my data may not be very reliable. Therefore, the validity of my conclusion has been affected although I feel that the trend shown is correct apart from the anomalous results obtained towards the end. Despite all the limitations I described before, I feel the investigation went very well, even better than I had originally anticipated. The accuracy of the results was certainly good enough to make a sensible conclusion. My conclusion is safe because even though the sources of error have a negative effect, the effect of temperature on Pectinase is still apparent. In my opinion, if the experiment had been conducted under more strict conditions and with more advanced instruments, the conclusion would not have been so different. The only difference might have been the individual results, which might have been more accurate and the graph might look slightly different. My Original Plan was altered in these aspects: * I had originally planned to use apples instead of plums but due to the fact that another person was doing the exact same experiment with apples. I decided to be different and used plums instead of apples and I'm glad I did. * I was initially going to use 1% Pectinase solution but, following the pilot study I found that 2% would be much more effective. FUTHER INVESTIGATION The enzyme Pectinase could be investigated even further in these aspects: 1. Effect of different concentrations of Pectinase on the amount of juice produced. 2. Comparison of juice produced from different fruits. 3. Investigating how Pectinase works in clarifying juice. 4. Effect of pH changes on Pectinase. 5. Comparison of microbial Pectinase with natural plant Pectinase. ...read more.

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Here's what a teacher thought of this essay

3 star(s)

*** A mostly well researched and carried out experiment that has produced some usable data. The candidate does need to ensure that terms like accuracy, precision, reliability or validity are correctly used at A level.
To improve:
Research and rationale
The rationale for the experiment is discussed and justified in terms of its scope and appropriate biological principles are discussed. A reasonable number of sources that were not standard A level text were quoted. The background could have been extended to include more on the different ways in which pectinase is used to increase fruit juice production. For example pulp can be left to oxidize for some time to rid the pulp of enzyme inhibitors.
There could be more consideration given to the key variables in the experiment as a number of key variables were omitted in the discussion. It is often better to list these in a table, with their appropriate control measures and an explanation given as to the likely effect on the experiment if these are not controlled well. The inclusion of controls to the experiment would have made the consideration of the results much easier.
The prediction could be made quantitative and greater biological knowledge used to explain it. The attempts to assess safety are superficial and would gain little credit under most current guidelines.
The candidate seems to have carried out the experiment well and recorded sufficient data. The headings of the table should include all units. Statistical tests were used appropriately to analyse the data.
Analysis and Evaluation
The choice of graph illustrated the trend well and the use of ICT included correctly plotted points, not a smooth curve. The explanations were sound and related to basic biological knowledge. The candidate should have considered the controls in the experiment more carefully as their lack meant that some of the interpretations of enzyme stability were dubious. The anomalies were recognized and commented upon. The modifications to the experimental methodology that were suggested were a little limited in nature and could have been mor thoroughly explored but there were sensible extensions proposed.

Marked by teacher Stevie Fleming 26/07/2013

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