Caffeine can be found in many products such as coffee, tea, soft drinks, energy drinks and even some sweets and over-the-counter medications. Caffeine is a bitter substance that stimulates the central nervous system, giving a boost of energy and increasing alertness. It is considered a psychoactive substance, a chemical substance that alters brain function, and is the only legal psychoactive substance on the market. Caffeine in soft drinks is a large contributor to the total amount of caffeine consumed per day in the U.S.
Function of Caffeine in Soft Drinks
Manufacturers of soft drinks claim they add caffeine into the beverages simply for taste. John Hopkins Medical Institute conducted a study to determine if there was a difference in taste depending on the caffeine content. It concluded that only 8 percent of the group of regular soft drink consumers could identify the difference between regular and caffeine-free soft beverages. Around 90 percent did not recognize a flavor difference between caffeinated and caffeine-free beverages. Because caffeine is a mood-altering substance it is thought that the addictive property of caffeine is what keeps people buying the product, in turn, increasing sales of soft drinks two to three fold between 1970 and 2010.
Analysis of Caffeine
The amount of caffeine in a beverage is determined by a method called high-performance liquid chromatography (HPLC). HPLC is used to analyze additives and contaminants in foods. Chromatography is a way to separate and identify compounds and determine purity and concentration of the compounds based on polarity. The reverse phase HPLC is the most popular method used, while UV absorbance detection is a common detection mode used.
How HPLC Works
The sample is automatically injected into the HPLC tube/column. It then passes through a detector and absorbs UV light, which then records a series of peaks. Each of the peaks represents a compound in the mixture, in this case caffeine. The area under the peak is what helps in determining the amount of the compound. When testing for the amount of caffeine in soft drinks, the higher the peak, or the larger the area under the peak, the more caffeine there is in the product.
Regulations
Caffeine is considered Generally Recognized as Safe (GRAS) by the Food and Drug Administration. The labeling regulations of caffeine vary widely depending how it is dispensed; medication vs. soft drink vs. energy drinks. Soft drink manufacturers have to limit the amount of caffeine they put in their products to 71mg per 12 oz. As far as labeling they only need to list "caffeine" as an ingredient in the ingredient list, they do not have to disclose how much caffeine there is in the drink. In 2007, a big step was taken in the industry--the top two soft drink companies decided to voluntarily disclose the amount of caffeine in each product directly on the packaging.
Comparison
The amount of caffeine varies greatly in soft drinks. Jolt contains the upper limit of 71mg per 12 oz ., while Mountain Dew and Pepsi One are the next highest containing 56mg and 55mg, respectively. Some of the diet beverages appear to have more caffeine than their regular counterparts--Diet Coke contains 47mg while Coca-Cola Classic has 35mg of caffeine. Some other common brands include Pepsi, 38mg, Diet Pepsi, 31mg, Sunkist Orange, 42mg and Dr. Pepper, 41mg. Non-cola beverages, such as 7-UP and Sprite or Sprite Zero, do not contain caffeine.
References
- John Hopkins Medicine: Caffeinated Energy Drinks-A Growing Problem
- Center for Science in the Public Interest: Caffeine Content of Food and Drugs
- Mayo Clinic: Caffeine Content of Coffee, Tea, Soda and More
- Archives of Family Medicine: Is Caffeine a Flavoring Agent in Cola Soft Drinks?
- Chemguide: High Performance Liquid Chromatgraphy--HPLC
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