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An Investigation into the effects of Concentration upon pectinase and the yield of apple juice it produces.

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Introduction

An Investigation into the effects of Concentration upon pectinase and the yield of apple juice it produces. Aim To investigate the effects of concentration upon pectinase and the yield of apple juice it produces. Introduction and Biological Knowledge Pectinase is an enzyme that specifically targets Pectin which bonds the long Cellulose strands together to form the outer core of the apple. Breaking these bonds would allow the cellulose strand to move more freely and therefore form a liquid - in this case apple juice. Pectin is a molecule similar to starch except that the repeating unit of pectin is galacturonic acid instead of glucose as in starch. Galacturonic acid is still very similar to glucose, except one of the carbons has a -COOH group attached instead of a CH2-OH. The pectin chain is held together by a bond between carbon 1 of one galacturonic acid and carbon 4 of the next one and so on. Pectinase splits the bonds between these galacturonic acids to shorten the pectin chain from large fragments in to many more small fragments. The actual catalytic mechanism introduces water so pectinase is known as a hydrolytic enzyme. It splits a water molecule and adds -H to one carbon in the bond and an -OH to the other one. Pectins are very good at binding water (pectin in jam/jelly is what makes it set), but only when the pectin molecules are quite large. So pectinase is used in industry to help increase yield of juice from fruit processing. In plants the pectin naturally functions as a "glue" to hold the cell wall together and also to "glue" cells together (the middle lamella, the bit between neighbouring cells is rich in pectin), so degrading the pectin enzymatically also makes it easier to digest the cellulose and other molecules as well as releasing water (juice). Schematic structure of a plant cell Pectinase are produced during the natural ripening process of some fruits, where together with cellulases, they help to soften their cell walls. ...read more.

Middle

Another aspect of my experiment, which I have now decided to change following the pilot run, is that I shall record the volume of juice obtained at intervals of 2 minutes rather than 5 as I feel this will show a more accurate rate of juice production. I was also able to distinguish the mass of apple that should be used for each experiment, 30kg. When I filtered the apple juice, I observed that the filter papers were absorbing some of the apple juice to prevent this from happening in my main experiment and from giving unreliable results I shall dampen the filter paper first with water. Distilled water must be used throughout the experiment as tap water contains impurities, which could affect the results from my experiment. I shall now go on to conduct my main experiment. Method Equipment needed Quantity No. Volume Apples 2 150kg Pectinase Enzyme 10ml (approximately) Distilled water 10ml (approximately) Knife 1 Cutting Board 1 5ml Syringes 2 Filter Funnels 5 Measuring cylinders 5 100cm3 Beakers 5 100cm3 Water Bath set to 40C 1 Stop Watch 1 Top pan balance 1 Coffee filter papers 5 Thermometer 1 Glass stirring rods 5 Marker pen 1 Procedure * Peel and chop apples, weigh into 5 equal quantities 30kg. Put into 5 separate beakers. * Measure out 5 4ml concentrations. 100% 4ml Pectinase 0ml D.Water 75% 3ml Pectinase 1ml D.Water 50% 2ml Pectinase 2ml D.Water 25% 1ml Pectinase 3ml D.Water 0% 0ml Pectinase 4ml D.Water Add to apple 30kg quantities. * Stir each beakers contents with clean glass rods. Keeping them separate. * Incubate the beakers in a water bath at 40C for 20 minutes. * Filter the juice from the apple pieces, using coffee filter papers in funnels placed in measuring cylinders. * Record the volume of juice obtained from each lot of apple at 2minute intervals. This experiment should then be repeated at least 3 times so averages can be obtained and more reliable results gained. ...read more.

Conclusion

This would ensure that the juice produced was due to the action of the pectinase enzyme. To further improve my experiment I would also ensure that the surface area of the sliced apple was the same each time, as this can also affect my results because in one sample there may be more surface area for the enzyme to attack. This should be kept as a constant. Another error in my method is that I did not take recordings of the results over a sufficient period of time. As it says in my background information: 'Enzyme treatment commercially takes anything from 15 minutes to 2 hours depending on the exact nature of the enzyme, the dosage rate, the reaction temperature and the variety of apple used.' Suggesting that the time enzyme treatment takes is dependant on several factors (the factor I was investigating was concentration (dosage) of enzyme), So I could have left the experiment going for a longer time period therefore acknowledging the time on average that enzyme treatment takes concerning concentration rate, gaining more reliable and detailed results. There are many investigations into pectinase that I could have done. For example instead of changing the concentrations of the enzyme the temperature could be changed, the ph and the variety of apple used could also be explored. As different apple types may have varying amounts of pectin, and celluloses in their cell walls and this in turn could effect the production of fruit juice. Another investigation could be one that investigates the differences in the effects of pectinase on the yield of fruit juice from different fruits such as pears, pineapples and oranges. You could also try replacing the pectinase enzyme with cellulose to see if this has the same effect as pectinase. The two enzymes could also be mixed together to see if using cellulose enzyme to break down the molecules of cellulose in the cell wall will effectively increase the yield of fruit juice obtained from fruits such as apples, which have a high proportion of cellulose in the cell wall. ...read more.

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