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To find out if temperature affects the amount of juice the enzyme pectinase releases from an apple.

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Introduction

Juicy Fruit Investigation Aim: To find out if temperature affects the amount of juice the enzyme pectinase releases from an apple. Prediction I predict that the temperature the pectinase will work best in is 30? - 40?, I think this will be the temperature the pectinase will be able to break down the most fruit into fruit juice. I do not believe the enzyme will work above 45? as it would become denatured. This is because I know most enzymes (similar to proteins) stop working/get destroyed above this temperature, as they are made up of protein. I also know that the temperature enzymes work best in the body at body temperature; 37? therefore I believe the higher the temperature is without going over 45? the faster the molecules will move and hit the enzyme molecules. An enzyme works when a substrate molecule bumps into a molecule of the correct enzyme, they fit together into a depression on the surface of the enzyme molecule. When this movement takes place the depression is called an 'active site'. A reaction takes place and the substrate products are released separately. Because the substrate molecules are different shapes they will only fit into certain enzymes. When the enzyme reaches a temperature too high it will change shape, therefore the substrate molecule would not fit. ...read more.

Middle

* We then moved the test tubes to a place suitable for the temperature we were looking at e.g. water baths, ice bath etc and left them to get to the temperature of their surroundings. Using a thermometer in one of the pectinase test tubes and one of the apple test tubes I monitored the temperatures being careful not to swap the thermometers around so none of the pectinase got mixed with the apple. * Once the test tubes had reached the temperature of their surroundings I poured 2mls of pectinase into each of the 3 test tubes and started the timer. * When 10 minutes had gone by I took all 3 of the test tubes and filtered them into measuring cylinders to see how much juice they had collected. * After the juice appeared not to be dripping through into the cylinder anymore I took all 3 readings, recorded them in my table and then found their average by adding them up and dividing the sum by 3. Fair Test: In my experiment my key variable was the temperature. The factors I kept constant were the amount of apple used, the amount of enzyme used and the time given. This made my experiment fair as I only changed one thing. ...read more.

Conclusion

Evaluation: Overall I am happy with the way my experiment went. I got positive results which were similar to what I predicted and the way they should have looked. Of course there were some things that could have been improved: * When the test tubes containing both pectinase and apple had been in one of the 6 temperatures for 10 minutes (the chosen amount of time) and were ready to be filtered into a beaker I found it hard to get them all out of the water baths and poured into the filters at the same time. In some of the hot temperatures some of the juice may have evaporated by the time I had filtered them, therefore altering my results. This could be improved by getting a partner to help me at this point in the experiment. * As we did this experiment over a span of 2 lessons the apple we used in the first lesson was different in the second. The apple we used on the first day was more broken down than the second therefore it had more of a surface area for the pectinase to work on than the apple that was more compact. The smaller the particles of apple; the easier the pectinase can break it down. This could have affected our results so perhaps if I were to do the experiment again I would do it all with the same sample of apple. ...read more.

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