Levels of Caffeine in Tea, Coffee and Soft Drinks - Lab Report Example

Aim Comparison of levels of caffeine in tea, coffee and soft drinks by using different methods Introduction Caffeine, a stimulant drug, is widely found in many foods and drinks that we consume. Caffeine belongs to a group of stimulants called methylxanthines, or xanthines, which occur naturally in a number of plants. Caffeine also acts as a diuretic, stimulates increased peristalsis in the bowel, and is a potent vasoconstrictor. It has an addictive effect on the body. It is therefore essential to know caffeine content in certain beverages. The nuts, seeds or leaves of plants are currently major sources of natural caffeine (Andrews et al, 2007). Several beverages like, coffee from the seeds of the Coffea arabica plant, Colas from Kola nuts, tea made from the leaves of Thea/camellia sinensis contain varying amount of caffeine content. Caffeine is also added back to other products as a food additive. In the USA, caffeine use and labeling is regulated by the Federal Food and Drug Administration. Naturally present caffeine in various ingredients is not required to be listed on the label. The decaffeination process of coffee and tea effectively removes about 97% of the caffeine. Caffeine levels should not be more than 2.5 percent of the product, to classify it as decaffeinated (Rafetto et al, 2005). Estimation of Caffeine: Caffeine content in food and beverages can be estimated by numerous methods. Few of these techniques comprise of the indespensable UV-Visible spectrophotometry, simple to use thin layer chromatography, more complex high performance liquid chromatography (HPLC), high performance thin layer chromatography (HPTLC), capillary (Spiller, 1998). HPLC is one of the most commonly used estimation methods. HPLC as a method to estimate caffeine content in beverages is described below. Calibration curve is made by using solutions of caffeine ranging from 5-1000 ppm. Samples are passed through syringe before loading onto the column; to get rid of any particulate matter. 60 μl of filtered sample is injected into the HPLC at a volumetric flow rate of 2ml/min. The elution solvent system consists of 65:35 mixture of water and methanol, and the total run time is 5 min. Approximate elution time for Caffeine is 0.9 minutes and peak area vs. concentration plot is constructed. Preparation for test samples depends upon type of beverage. Carbonated soft drinks require a degassing step before filtration (Yuhas, 2002). The beverages are analyzed in a same way as standards. Extraction methods for Decaffeination Decaffeination essentially is accomplished in five steps (Clarke and Vitzthum, 2001). 1. Swell the raw material with water, which solubilizes caffeine-complex. This aids in extraction of caffeine in later steps. 2. Extract with the solvent 3. Steam stripping to remove the solvent residues 4. Regenerate the adsorbent 5. Adjusting the processed material to initial moisture levels There are three common decaffeination methods: the use of organic solvents, either methylene chloride or ethyl acetate; water extraction (Swiss water process or European water process); and supercritical carbon dioxide. Most of decaffeinated coffee today is processed with solvents. Studies suggest that methylene chloride (dichloromethane) is shown to be carcinogenic, and the National Cancer Institute’s labels it as a possible human carcinogen. In the decaffeination process, the solvents are removed from the processed material, but residues have still been found in decaffeinated coffee and tea. When water and carbon dioxide are used to decaffeinate, a measurable residue is not found in the processed material. Retention of flavor in decaffeinated beverages depends upon the extraction method. Methylene chloride extraction retains the flavor but leaves a dry taste in the mouth; water extraction and CO2 extraction smudge the flavor of the beans and ethyl acetate adds a sweet fruit flavor (Rafetto et al, 2005). Ethyl acetate extraction: Ethyl acetate is a chemical found naturally in many fruits, hence ethyl acetate decaffeinated beverages are also known as ‘naturally decaffeinated’ products. Ethyl acetate is a chemical used as a solvent to extract caffeine from various raw materials. Molecules of caffeine bond to molecules of ethyl acetate. The materials are softened in a water bath or in steam. The next step is to process the materials with ethyl acetate by direct or indirect techniques. Indirect method, the material is soaked in solvent ethyl acetate. In indirect process, the material is soaked in water, before extraction with ethyl acetate. Water extraction This method is used primarily for coffee decaffeination. The process resembles indirect method employed to extract caffeine by ethyl acetate processing, the only difference being processing without any chemicals. After leaching the caffeine in hot water for a stipulated a period, the solution is then passed through an adsorbent for caffeine removal. Various supports are utilized for adsorption process. Non-ionic resins are found to have greater affinity for caffeine. Activated carbon fibers are more selective, with a loading capacity of 40% by weight (Clarke and Vitzthum, 2001). Eluted water is returned to the processed material, to reabsorb flavors and oils. In the "Swiss Water Process," the beans are soaked in a coffee-flavored solution. This results in the caffeine being extracted without removing the coffee flavors. Analysis Data Water extraction method Tea Mg content Tea extract 1 Tea extract 2 Tea extract 3 Ethyl acetate extraction method Tea Mg content Tea extract 1 Tea extract 2 Tea extract 3 Water extraction method Coffee Mg content Coffee extract 1 Coffee extract 2 Coffee extract 3 Ethyl acetate extraction method Coffee Mg content Coffee extract 1 Coffee extract 2 Coffee extract 3 Water extraction method Soft drink Mg content Soft drink extract 1 Soft drink extract 2 Soft drink extract 3 Ethyl acetate extraction method Soft drink Mg content Soft drink extract 1 Soft drink extract 2 Soft drink extract 3 Caffeine Content Of Popular Drinks Soft Drinks 12-ounce beverage milligrams Red Bull (8.2 oz) 80.0 Jolt 71.2 Pepsi One 55.5 Mountain Dew 55.0 Mountain Dew Code Red 55.0 Diet Mountain Dew 55.0 Kick Citrus 54.0 Mellow Yellow 52.8 Surge 51.0 Tab 46.8 Diet Coke 45.6 Shasta Cola 44.4 Shasta Cherry Cola 44.4 Shasta Diet Cola 44.4 RC Cola 43.0 Diet RC 43.0 Dr. Pepper 41.0 Diet Dr. Pepper 41.0 Diet Sunkist Orange 41.0 Mr. Pibb 40.0 Sugar-Free Mr. Pibb 40.0 Red Flash 40.0 Sunkist Orange 40.0 Slim-Fast Cappuccino Delight Shake 40.0 Ruby Red 39.0 Storm 38.0 Big Red 38.0 Pepsi-Cola 37.5 Pepsi Twist 37.5 Diet Pepsi Jazz 37.5 Diet Pepsi 36.0 Wild Cherry Pepsi 38.0 Diet Wild Cherry Pepsi 36.0 Diet Pepsi Twist 36.0 Aspen 36.0 Coca-Cola Classic 34.0 Cherry Coke 34.0 Lemon Coke 34.0 Vanilla Coke 34.0 Diet Cherry Coke 34.0 Snapple Flavored Teas (Reg. or Diet) 31.5 Canada Dry Cola 30.0 A&W Creme Soda 29.0 Nestea Sweet Iced Tea 26.5 Nestea Unsweetened Iced Tea 26.0 Lipton Diet Green Tea with Citrus (16.9 oz) 23.0 Barqs Root Beer 23.0 A&W Diet Creme Soda 22.0 Slim-Fast Chocolate Flavors 20.0 Lipton Brisk, All Varieties 9 Canada Dry Diet Cola 1.2 Diet Rite Cola 0 Sprite 0 7-Up 0 Mug Root Beer 0 Diet Barqs Root Beer 0 Sundrop Orange 0 Minute Maid Orange 0 A&W Root Beer 0 Slice 0 Sierra Mist 0 Fresca 0 Other Beverages 8-ounce Beverage milligrams Coffee, Drip 115-175 Coffee, Brewed 80-135 Coffee, Espresso (2 ounces) 100 Coffee, Instant 65-100 Tea, iced 47 Tea, brewed, imported brands (avg.) 60 Tea, brewed, U.S. brands (avg.) 40 Tea, instant 30 Tea, green 15 Hot cocoa 14 Coffee, Decaf, brewed 3-4 Coffee, Decaf, instant 2-3 SOURCES: National Soft Drink Association, US Food and Drug Administration, Bunker and McWilliams, Pepsi, Slim-Fast. References Karen W. Andrews & Amy Schweitzer & Cuiwei Zhao & Joanne M. Holden & Janet M. Roseland & Mary Brandt & Johanna T. Dwyer & Mary Frances Picciano & Leila G. Saldanha & Kenneth D. Fisher & Elizabeth Yetley & Joseph M. Betz & Larry Douglass The caffeine contents of dietary supplements commonly purchased in the US: analysis of 53 productswith caffeine-containing ingredients. Anal Bioanal Chem (2007) 389:231–239 Meri Rafetto, Stephen Cherniske and Gerri French, Effect of Decaffeinated Coffee on Health ©Teeccino Caffé 2005, pp. 1-11 URL:www.teeccino.com/PDFs/DECAF.pdf Gene A. Spiller. Caffeine . Published by CRC Press, 1998 Ben Yuhas. Determination of Caffeine Content in Beverages with HPLC. Chem 384 March 2002 www.owlnet.rice.edu/~chem384/binstuf/HPLC_Caffeine_2002.pdf Ronald Clarke and O. G. Vitzthum, 1 edition (February 15, 2001). Coffee: Recent Developments, Publisher: Wiley-Blackwell, 2001. National Soft Drink Association, US Food and Drug Administration, Bunker and McWilliams, Pepsi, Slim-Fast. Read More