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Experiment to Investigate the effect of the size of Applie Pieces used on the Yield of Juice Produced by Apples Using the Enzyme Pectinase

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Introduction

EXPERIMENT TO INVESTIGATE THE EFFECT OF THE SIZE OF APPLE PIECES USED ON THE YIELD OF JUICE PRODUCED BY APPLES USING THE ENZYME PECTINASE. AIM The aim of this experiment is to investigate how the enzyme pectinase effects the yield of juice produced by apples and also how the size the apple pieces effects the efficiency of the enzyme pectinase. PRELIMINARY WORK To help me with my investigation, I did a preliminary experiment investigating a key element of my actual investigation - whether the enzyme pectinase actually had an effect on the yield of juice produced by apples. I also needed to work out a suitable time to leave the apple pieces filtering and I also considered the fact that a preliminary experiment would be useful in helping me acknowledge and prevent any errors that may occur in my real investigation. METHOD 1. A medium-sized apple was chopped into small pieces and half was placed in beaker A, and the other half was placed in beaker B (to ensure there were equal amounts in both beakers, each beaker was weighed empty and then re-weighed with the apple pieces). 2. 2cm3 of diluted pectinase enzyme was added to beaker A and 2cm3 of distilled water was added to beaker B using separate syringes. 3. The contents of both beakers was then stirred using separate glass rods. 4. The two beakers were then incubated in a water bath set at 40oC for 20 minutes. 5. The juice from the apple pieces in each beaker was then filtered using coffee filter paper in funnels into separate measuring cylinders. ...read more.

Middle

Temperature has an immense affect of the efficiency of enzymes. Enzymes have a unique optimum temperature (around 40oC) which they work best in. Below the optimum temperature, the molecules involved in the reaction will be provided with less kinetic energy meaning that the numbers of collisions between enzyme and substrate will decrease, as the speed of molecular movement is decreased. Any temperatures above the optimum will cause the enzymes to be denatured - bonds holding the structure together will be broken and the active site loses its shape and will no longer work. Therefore during reactions involving enzymes, the temperature has to be greatly considered. The pH condition in which an enzyme is made to work also has a great effect on the efficiency of the enzyme. As with temperature, enzymes have an optimum pH (usually a small range). If the pH changes much from the optimum range, the chemical nature of the amino acids can change. This may result in a change in the bonds and so the tertiary structure may break down, causing the active site to be disrupted and the enzyme to be denatured. Concentration is another important factor effecting the efficiency of enzymes. Firstly the enzyme concentration has to be considered. At low enzyme concentration there is great competition for the active sites and therefore the rate of reaction is low. As the enzyme concentration increases, there are more active sites and the rate of reaction will increase. However, increasing the enzyme concentration beyond a certain point has no effect because the substrate concentration becomes the limiting factor. ...read more.

Conclusion

The pH and concentration of everything were kept constant throughout the experiment. * The same amount of apple pieces (i.e. same amount of apple juice) was put in each beaker and this was controlled by weighing exact amounts of apple pieces. * The size of the apple pieces were measured accurately using a ruler to ensure that e.g. all apple pieces in the 3mm test were actually 3mm in length. * Distilled water was used instead of tap water to ensure that no unwanted substances would interfere with the control experiment i.e. distilled water is purer. * Each apple length was repeated three times and an average was taken. If the three sets of results were marginally different, I would know that something had gone wrong in the experiment. Also, repeating each concentration gives me a wider set of results which would give me a much more accurate figure when averaged. * The volume of the diluted pectinase enzyme/distilled water used was the same for each experiment. * The diluted pectinase enzyme used was of the same concentration for all experiments. * The stop clock was started as soon as all the apple pieces were in the filter funnels; therefore each experiment got the same time to produce the apple juice- 40 minutes. * The readings on the measuring cylinder were noted down very carefully because it is quite easy to make a mistake when reading off such small scales. Also, the measuring cylinders originally contained 10cm3 of acid to make reading off the scale much more easy. * A measuring cylinder with a large scale was used to measure out the amount of apple juice produced because it much more accurate. ...read more.

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