Effect of Roasting Coffee on Caffeine Conten

Effect of Roasting Coffee on caffein ContenIntroductionCoffee has been a popular drink since 20th century, non only because of its variant colors and flavors due to antithetic degrees of cook, but also the military force on which it great deal keep you to stay awake and to finish your job. It is usu every(prenominal)y known that the reason for java to possess this effect is because of the caffein inside the chocolate beans. In general, there ar four main types of roast methods in the patience, namely, Light Roast, Medium Roast, Full Roast and Double Roast.There argon a variety of uses on caffeine nowadays. By interfering with adenosine in wit and body, it moderates new transmission of signals in CNS, Central Nervous System, and therefore keeps people awake1. Due to its short half-life in human body, around 4-10 hours on average2, it potty be use to augment the effect of analgesic for pain control3 Also it has effect on delaying the muscle fatigue. However, caffeine p ush aside cause negative effect on human body, for example, increase the heart rate, breathing rate and makes people feel more alert and energetic, which is also the reason why International surpassing Committee forbid high caffeine wasting disease. Moreover, it is a mildly addictive drug, so some people mountain non control the consumption of caffeine under overdose, which could kick in to caffeinism.4 Also, gibe to the a study held by Montreal University, if pregnant woman consume more than 1.5 cup of java, the mishap of miscarriage is doubled if consume more than four, the chance of miscarriage is tripled.5Therefore, the choice of caffeine consumption from coffee becomes critical due to its harmful effect on human body. It is advised that, if necessary, 100-300 mg per day of caffeine consumption is acceptable. However, people atomic number 18 usually lack of knowledge slightly the caffeine message in the coffee and bring no paper what substance scarce is in the coff ee they ar drinking. Thus, they often use their senses to identify the caffeine content in coffee relative to each another(prenominal). However, there atomic number 18 a make do of myths ab reveal this method. For example, those darker coffee has more caffeine than lighter coffee due to its darkness or that the caffeine is destroyed during roasting in higher temperature, so the caffeine content in lighter coffee is higher than that of darker coffee. To proceed over-dosing of caffeine from coffee, it is vital for people to have the general idea of comparing the caffeine content in different coffee when buying a them.In this essay, the caffeine contents in coffee beans roasted in different degrees are examined by experiment through the extraction of caffeine by chemical core. The result would be interpreted by focusing on the roasting unconscious process, as coffee beans experience greatest change in physical or chemical change during roasting. Although there are a lot of sub- degrees of the main four roasting degrees, only one sub-degree from each degree would be selected as representative.Research QuestionDoes different roasting degree run into the caffeine content in coffee beans?Background InformationOriginal Coffee beansThe airplane pilot coffee beans are unripened in color. They reserve non-volatile alkaloids, proteins and amino acid, carbohydrates, lipids, non-volatile chlorogenic acid, and volatile6 compounds. Among the non-volatile alkaloids, caffeine is the nigh abundant. It contains 1-2.5% w/w 7 of kilobyte coffee been. caffeinCaffeine is a white, crystalline odorless and bitter tasting solid.8 It exists in the localise of coffee beans as a natural pesticide. Its formal name is trimethylxanthine, or in agreementatic naming 1,3,7-trimethylxanthine or 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione.9 The chemical formula of caffeine is C8H10N4O2. It is a polar10 organic compound that contains carbon, nitrogen, hydrogen and oxygen. Its d ensity in solid form is 1.23 g/cm3. Due to the presence of nitrogen in the compound, caffeine is base in nature. Since it is a polar molecule, it is soluble to irrigate, especially in fervent water. The solvability of caffeine in water is 22 at 25, 180 at 80, and 670 at 100.11 Under pressure of standard ambient temperature and pressure12, the melting point of caffeine is 23813 and it can also sublime at 178in nearly vacuum14, which will be explained by phase draw next.Phase DiagramThree general phases of matter are solid, liquid and fluid. Change of phase does not only depend on the temperature, but also the surrounding pressure acting on the chemicals. For example, the boil point of water is 100, under standard ambient temperature and pressure. However, if the is placed in a lower atmospheric pressure, the boiling point of water is decreased since the vapor pressure is already greater than the atmospheric pressure, so water molecules can avoidance from the water surface in a lower required aught. Therefore, each compound can undergo phase change to the three phases in different combination of temperature and pressure. Figure 2 is a phase diagram of . The lines dividing the diagram into sections represent that under certain temperature and pressure, would undergo change of phase, which is equilibrium mingled with the twain phases that the line is dividing. For example, the red line, if A 1, then the corresponding melting point increases, epoch the corresponding boiling point, A, decreases.Each element has their own phase diagram to illustrate the transition of phases under different combination of temperature and pressure. Figure 3 is a phase diagram illustrating the phase transitions of caffeine, which is different from . This is critical in ulterior interpretation of the result in the experiment. It is because roasting process involves temperature and pressure change.Roasting processThe main purpose of roasting coffee beans is to exterminate tox ins, enhance the gustatory sensation and concentrate the odor wanted. Since viridity coffee beans are hard, little smell and contain a lot of compounds that are bitter in taste. Therefore, by roasting, it can result in both physical and chemical change in the green coffee beans. Since caffeine is the main factor that is concerned in this essay, other chemical change will not be discussed. Although there are a lot different roasting processes in the industry, such as fluidized fork up roasting, fast roasting or horizontal rotating drum, the basic process of roasting is similar. During roasting, there are 10% to 20% lost in weight from the green coffee beans. Here is a summary of roasting process of coffee beansHeating of Green Coffee Beans from 3-5 minutes (ab appear 25 to 100)The green coffee beans are heated so that the water in the original coffee beans evaporates at a very fast rate. As this point, the green coffee beans turn from green to yellow due to caramelization of sugar in the coffee beans.Heating of Yellow Coffee Beans from 5th-9th minutes (about 170to 200)The yellow coffee beans are further heated and separate to turn to brown in color as more sugar being caramelized. Carbon dioxide and water are forced to escape out of the coffee beans due to the high pressure inside, as the temperature is very high, which also causes the expansion in surface of coffee beans. The aroma also starts to give out at this stage.First crack from 10th-11th minutes (about 210)A first sound of crack gives out as the coffee beans expand to almost double in size from green coffee beans in high temperature. Familiar aroma is given out and the coffee beans turn golden brown at this stage. subsequently this stage, according to different degrees of roasting required, the coffee beans will undergo different temperatures and time periods for further heating. During the process, the sugar is caramelized further and coffee oil is released.Light roastTo win light roasted coffe e beans, the beans from stage 3 are to be roasted about one more minute in about 215 in the first place the second crack.Medium roastFor further half to one minute from light roasted in about 230, a second crack occurs and it means medium roast is finished.Full roastIf continued for half to one minute from medium roasted in about 240, full roasted coffee beans are collected.Double roastThis is the most common final step that coffee beans would be roasted, which is acquired from continuing the roasting from full roasted coffee beans for about half a minute more in about 245. The sugar in the coffee beans at this stage is started to burn and degraded.The above heating process can be achieved by either roasting the coffee beans on a hot plate, which is a traditional roasting method in industry or in home roasting, or passing the coffee beans by high temperature steam.MethodVariablesIndependent Degree of roasted coffee beansDependent Caffeine extracted from the coffee beans (g)Controll ed Mass of roasted coffee beans (g)Brand of coffee beans (Starbucks)Apparatus The following apparatus are used in this experiment.Chemicals The following chemicals are used in this experiment.ProceduresExtracting chemicals compounds out of coffee beansMeasure 100mL of distilled water by graduated cylinder rain buckets the water into a 200mL beaker.Place the beaker on a hot plate and heat the hot plate to 100.Place a weighing boat on an electronic scale and tare it.Measure 3g of coffee beans, in form of powder, on the electronic scale and volume it.Add the 3g of coffee powder into the boiling water. consumption glass rod to stir the solution during heating. after(prenominal) the water boils, which means it reaches 100, set the temperature to 80 and allow the solution to stand for 20 minutes to extract as much caffeine as possible. accounting of Stage 1 procedureSince caffeine is a polar molecule, it fragments in water, especially in hot water. It is because increase in temperature leads to increase in solubility of solids, as less energy is required directly from the molecule to break the water molecules a serving from each other. Use of distilled water instead of tap water is to prevent any interruption from foreign ions exist, such as decreasing the solubility of caffeine. The water volume to coffee powder grass ratio has to be large to ensure that there is enough water to dissolve caffeine. Hotplate is preferred as it is easier to manipulate the temperature. The decrease in temperature from boiling point is to prevent any further evaporation of water, which may decrease the amount of caffeine extracted from coffee beans powder. Also, the coffee beans have to be in powder form in order to increase the surface area to dissolve completely in the solution.Assumption in Stage 1 procedureThe coffee beans are originated from the said(prenominal) coffee beans farm.No other procedure apart from roasting and grinding is done.The coffee beans are roasted in the sam e method.The degree of roasting is exactly same as listed on the package.Separate caffeine from other chemicals in the solutionUse filter paper and filter move to filter out large remaining solids.After the solution in stage 1 is cooled down, measure 2g of sodium change by electronic scale and add it to the solution.Use glass rod to stir the solution and allows sodium carbonate to dissolve in the solution.Use a pipette of 25 mL to transfer 25 mL of dichloromethane to the solution in order to obtain accurate measurement and stir it with a glass rod for a few minutes.Pour the solution into a separating move and cover it.20Use a stand to hold the separating funnel and allow the solution in it to separate into two unmixable layers.Precaution of Stage 2Since dichloromethane is a volatile organic solvent, it is toxic when inhaled. Thus, starting from step 3 in Stage 2 and onward, all steps in the experiment have to be carried in the skunk board.Make sure the opening of the separating funnel is closed before pouring the solution. history of Stage 2 procedureApart from caffeine, the solution from stage 1 also contains different compounds extracted from the coffee beans, which are soluble in water too. The most abundant amount among the other compounds is tannin, which usually exists in plants products. Therefore, the addition of sodium carbonate is to remove those compounds other than caffeine by allowing those compounds to be more soluble and hence, allow them to dissolve in water instead of other solvents.The addition of dichloromethane is the most important procedure. It is a good organic solvent to dissolve caffeine. Although caffeine is a polar molecule and has dipole moment of 3.64D22, it dissolves more readily in less polar dichloromethane, which has dipole moment23 of 1.14D24, while H2O 1.84D25. It is because caffeine is a large molecule, so small charges are distributed over a large distance, which makes the molecule less polar than water even though is has big value of dipole moment than water. Therefore, it dissolves more readily in dichloromethane than in water.Since the preindication of dichloromethane is far less than water and is almost non-polar, it is not miscible with water, and due to its molar mass, 84.93g/mol, which is heavier than water molecule, 18.02g/mol, it sinks in the separating funnel.Assumptions in Stage 2 procedureAll caffeine in coffee beans dissolves in the boiling water from stage 1All caffeine is dissolved in dichloromethane from water and no other compounds.Completion of caffeine extract (In fume board)Label a beaker for the number of trial of a particular broad of coffee beans.Weigh the mass of a beaker by electronic balance and record it.Place the measured beaker under the separating funnel and open the funnel to run the lower dichloromethane down to the beaker.Cover can be opened a little in order to add atmospheric pressure inside the funnel, so that solution can run down smoother.Close the cover of the funnel when reaching the separating line and allow the solution to run slowly.Close the funnel when the line of separation is reached at the tip of the funnel.Place the beaker with collected dichloromethane on a hot plate.26Turn the temperature of hot plate to 100.Wait until all solutions are evaporated and the beaker is dried and white crystals remain.Allow the beaker to cool down then measure the mass again on the electronic scale and record it. The difference surrounded by the mass of beaker in step 1 and step 9 in Stage 3 is the mass of caffeine extracted from the coffee beans.Explanation for Stage 3 procedureEach beaker has different mass, so every individual mass must be weighed before usage. Step 1 must be done if trials are being done simultaneously. If some extra solutions from the upper part of the separating funnel are obtained, the entire procedure has to be started again. Since the boiling point of dichloromethane is 40, 100can make sure that any water and dichl oromethane are evaporated while 100is still far lower than the point of sublimation of caffeine in vacuum.Assumption in Stage 3 procedureAll dichloromethane is collected in the beaker.Only caffeine remains in the beaker after evaporation of other solution.Finally, repeat the entire procedure to obtain 5 trials result for each kind of roasted coffee beans. Therefore, there will be 20 results obtained.After all procedures are done, make sure all the apparatus which have tie with dichloromethane are placed inside the fume board and all solutions are poured into a big beaker. Label the beaker as toxic organic emaciate in order to allow the technician to dispose or treat them correctly.Raw dataObservationWhite precipitates remained.The precipitates are odorless.White precipitates stick on the piece of ass of the beaker.Conclusion and AnalysisFrom the calculations and Diagram 1, it can be seen that the percentages of caffeine existing in each coffee beans roasted in different degree ar e very closed. Therefore, the answer to the research question based on the result should be the caffeine content in a coffee bean is not affected during the roasting process. The result is reliable since all percentages lie between 3.2% and 4.0%, which are between the greatest value of lower limits and the lowest value in the upper limits of all percentages. Moreover, the trend shows neither increasing nor decreasing as the degree of roasting increases. Thus, there should not be any relationship between the degree of roasting and the caffeine content in the corresponding coffee beans. I will now interpret the results with regarding the background knowledge.Referring back to the roasting process, it is make believe that no chemical is added during the roasting process. However, the roasting process involves high temperature on direct heating with metal pans or using high temperature steam as alternative. One myth about the roasting process is that people claim that some caffeine is destroyed or evaporated during roasting under high temperature, so lighter coffee beans contain more caffeine than darker coffee beans. However, most of the roasting temperatures are under the melting point of caffeine, which is, indeed, not enough energy to destroy intra-molecular bonds. Although the temperature used for double roasted coffee beans are a little higher than the melting point of caffeine, the temperature only stands for about half a minute, which is not enough for the internal part of coffee beans to rise to melting point of caffeine. Neither, therefore, destroy nor evaporation of caffeine is unlikely to occur during the roasting process.Moreover, some myths say that due to the fact that the point of sublimation of caffeine is 178 and the temperature for full roast and double roast is already beyond that temperature, which exceeds 200, thus, the caffeine content in darker coffee beans is again described as less caffeine content that lighter coffee beans. It seems to be reasonable at first, but apart from temperature, we also estimate the pressure in roasting process, since phase change depends on temperature and pressure as mentioned before in this essay. Considering the method of heating green coffee beans directly, in order to keep the temperature over 200, it is necessary that the system of the roasting process is under a closed condition, so that less energy is lost to the surrounding. check to the Ideal Gas Law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles of gas molecules, R is the gas constant and T is temperature. As the system is closed, the volume, amount of gas and R, indeed, are constant. Therefore, if the temperature increases, the pressure also increases in the system. Same condition is in the method of using high temperature steam. Although it is commonly known that gas is the highest phase and the temperature cannot increase anymore, it is possible to create a steam with higher temperature than its boiling point, which is in a closed system. So if 200 steam is to be used, the roasting system has to be closed. Applying the same principle as before, the pressure also increases with the increase in temperature.Refer to figure 3, the phase diagram of caffeine. As the pressure increases, the docile line, the melting point of caffeine increases, the red line. Since the atmospheric pressure is increased to against the vapor pressure of caffeine, so more energy needed to break the forces between caffeine molecules in solid, which is an exothermic reaction27. Also, from the diagram, the line representing the sublimation point, purple rectangle, is only under relatively low pressure and temperature, as 178under vacuum condition, which is not the case in roasting coffee beans. Thus, it is incorrect to say that caffeine sublimes during roasting process.To conclude, high temperature and pressure in roasting process are the reasons that the caffeine content is not affected regardless t he degree of roasting that the coffee beans have achieved. Therefore, even different degree of roasted coffee beans is used to brew coffee, the caffeine consumption is the same no matter which type of coffee you prefer. Indeed, decaffeinated coffee is not taken into account.Limitations and EvaluationsRandom errors Random error arises since caffeine may not be all dissolved in dichloromethane since it still has a little solubility in room temperature water. Furthermore, the caffeine extracted by dichloromethane may contain impurities, which affect the mass of caffeine recorded. Also, the measurement using graduated cylinder causes uncertainties. Moreover, the use of other equipments such as electronic balance, which causes 0.01g on the mass measured. dogmatic errors The quantity of sample is too small, which causes unclear results obtained since large difference may be obtained if sample has larger quantity. If there is any difference of caffeine content, it would be more obvious if increase the amount of each coffee powder sample used. However, due to the fact that school laboratory do not have a large beaker at the time the experiment was performed, which required more than 200mL, only small amount of sample in each trial can be used in order to keep a large ratio between the volume of water and the mass of the coffee powder.Moreover, the major dictatorial error is the separation of two layers in separating funnel. Since the running of dichloromethane into a beaker is manipulated by hands and through the observation. To ensure that all dichloromethane is collected, the closure of the separating funnel is a little delayed due to the bubbles in the separating line, which blurred the exact separating take. Therefore, a little solution of the upper part, which contains the impurities from coffee beans, is added into the dichloromethane in the beaker. After the evaporation, since sodium carbonate is added before and it has high boiling point due to its ionic str ucture, its mass contributes to the mass weighed on the electronic balance.Methods to resolve the major self-opinionated error- Sublimation of caffeineIn order to resolve the major systematic error, a further step can be done if equipment is allowed in school laboratory. Since caffeine sublimes well under vacuum at 178, as no air molecules against the vapor pressure of caffeine, the collected caffeine can be placed into a flask connecting to a aspirator, which keeps the condition in vacuum, and have a cold finger above it and a heat source below the flask. Caffeine can then sublime and precipitate on the cold finger. Thus, pure caffeine can be collected and weighed.Further unresolved question and suggested investigationAlthough the caffeine content is not affected by roasting, a step backward can result in an unresolved question, which is whether green coffee beans grown from different places contain different level of caffeine inside? A suggested way to do so is that buy different coffee beans of same roasted level from different locations around the world. This can be done by using internet shopping. After, extract caffeine from each example and compare the caffeine content in each coffee bean from different location.Since there are more and more methods of roasting in the industry, such as fluidized bed roasting and fast roasting29, it would be interesting to investigate whether these new methods of roasting can affect the caffeine content in the coffee beans even they are claimed to be same degree of roasting after all.BibliographyA, Nehlig JL, Daval G, Debry (1992). Caffeine and the interchange nervous system Mechanisms of action, biochemical, metabolic, and psychostimulant effects. Brain Res RevFP, Meyer E, Canzler H,Giers H. Walther (1991). Time course of inhibition of caffeine elimination in response to the oral depot incumbrance agent Deposiston. Hormonal contraceptives and caffeine elimination. Zentralbl GynakolOxford A-Z of Medicinal Drugs Oxford Press.Kent, Michael (1997). Oxford Food Fitness (A Dictionary of diet and exercise) Oxford University Press.Anderson, dungaree Deslein, Barbara. The Nutrition Bible William Marrow and Company, Inc.LEUNG, T. M. LEE, C. C. Inorganic Chemistry and Chemistry in Action Fillans.Library for Science. .About.com Drug bank Purdue University Online written material Lab Look for chemicals Carleton College University of British Columbia Coffee-Makers-Caf Coffee-Tea Sweet Marias Sonora Environmental Research Institute, Inc. The Scripps Research Institute City Collegiate New Mexico Tech Ezine Article Beverage.cc PubMed database AppendixChemicals in green coffee beansNon-volatile alkaloidsCaffeine, theophylline, theobromine, paraxanthine, liberine, and methylliberine are present, while caffeine is the most abundant non-volatile alkaloid, which is about 1-2.5% w/w of a green coffee bean. Also, caffeine acts as a natural insecticide for the plant. Moreover, caffeines half life is 5.7 hours in a n ormal adult body.31Proteins and amino acidsProteins and amino acids make up 8-12% w/w of a green coffee bean.CarbohydratesCarbohydrates account for 50% w/w of a green coffee bean, mostly polysaccharides.LipidsLipids, ester, long chained unsaturated fatty acids and amides are found in green coffee beans. The fatty acid is saturated during roasting process, which accounts for the coffee oil.Non-volatine chlorogenic acidsChlorogenic acids are antioxidant. They are good for health, but 70% of them are destroyed during roasting process.Volatile compoundsVolatile compounds are found in green coffee beans as aldehydes, short-chained fatty acids and nitrogen containing aromatic molecules. However, the aromatic molecules in green coffee beans are unpleasant, which is the reason that coffee beans are roasted in order to form pleasant odor of aromatic molecules.Degree of roastingIt can be seen that although dipole moment of caffeine is very large, larger than water, the size of the molecule is very large compared to water and dichloromethane. Therefore, charges are spread widely, which makes the polarity of caffeine molecule less polar. Thus, caffeine dissolves more readily in dichloromethane than in water or sodium carbonate, which is ionic compound. Sodium carbonate is used to react and make some compound other than caffeine to be more soluble to water, such as tannin.34Nehlig, A, Daval JL, Debry G (1992). Caffeine and the central nervous system Mechanisms of action, biochemical, metabolic, and psychostimulant effects. Brain Res RevMeyer, FP, Canzler E, Giers H, Walther H. (1991). Time course of inhibition of caffeine elimination in response to the oral depot contraceptive agent Deposiston. Hormonal contraceptives and caffeine elimination. Zentralbl GynakolOxford A-Z of Medicinal Drugs, Oxford Press.Michael Kent (1997). Oxford Food Fitness (A Dictionary of diet and exercise). Oxford University Press.Jean Anderson, Barbara Deslein. The Nutrition Bible. William Marrow a nd Company, Inc.Volatile means tendency of vaporization.w/w = weight/volume percentage solutionLibrary for Science http//www.chromatography-online.org/directory/analt-235/page.html About.com http//chemistry.about.com/od/moleculescompounds/a/caffeine.htmDrug bank http//www.drugbank.ca/cgi-bin/getCard.cgi?CARD=DB00201Electrons are unevenly distributed.Purdue University Online Writing Lab http//employees.oneonta.edu/knauerbr/chem226/226expts/226_expt06_pro.pdf25and 1 atmT. M. LEUNG, C. C. LEE, Inorganic Chemistry and Chemistry in Action, Fillans.Look for chemicals http//www.lookchem.com/Caffeine/Original from Carleton College http//serc.carleton.edu/research_education/equilibria/other_diagrams.html Red line added as example.Original from University of British Columbia http//www.chem.ubc.ca/courseware/123/tutorials/exp10A/sublimation/Coffee-Makers-Cafe http//www.coffee-makers-cafe.com/coffee-roasting.htmlroastHomeCoffee-Tea http//www.coffee-tea.co.uk/commercial-roasting.php Sweet Marias http//www.sweetmarias.com/roasting-VisualGuideV2.phpThe method of extracting caffeine from coffee is improved by myself from originally design from Sonora Environmental Research Institute, Inc. www.seriaz.org/downloads/4-caffiene.pdfAll coffee beans are from same brand- Starbucks.Using separating funnel is more accurate than pouring the solution in another beaker by hand and using filter paper to remove the remaining unwanted solution from the original design.Fig. 4 separating funnels diagram is from Jindal Medical Scientific InstrumentD = Debye = unit of dipole moment. Look for chemical http//www.lookchem.com/Caffeine/Dipole moment is the vector sum of polarity.The Scripps Research Institute http//www.scripps.edu/chem/finn/Scipdfiles/dipolemoments.pdfCity Collegiate http//www.citycollegiate.com/dipolemoment.htmCalcium sulphate is not used as mentioned in the original procedure, since it cannot be removed after wards, which could affect the mass of caffeine collected.Exothermic re action means there is a net energy given out as heat.New Mexico Tech http//infohost.nmt.edu/jaltig/Chem333LCaffeine.pdfEzine Articles http//ezinearticles.com/?A-Look-at-the-Coffee-Roasting-Processid=1802022Beverage.cc PubMed database Sweet Marias Rare case that the coffee beans are totally blackened.Sonora Environmental Research Institute, Inc.