How Do UV Spectrophotometers Analyze Caffeine Levels? : Using Light Absorption to Measure Coffee

I am not really a morning person, so I require a little motivation every day to get myself up out of bed. My morning cup of coffee is one of my favorite rituals, and I’ll admit that the jolt of caffeine is an obvious bonus for kick-starting my day. However, for the millions of other people who share a similar love for this hot beverage, non-caffeinated versions are sometimes a better option due to various considerations. Coffee producers need to offer a variety of options for consumers that either provide that major caffeine jolt or ensure that the caffeine intake is minimized, so that consumers may be assured they are getting what they’re expecting. This process is highly dependent on the use of UV spectrophotometry and light absorption measurements.

coffee light absorption
Coffee is a popular drink around the world and is available in a variety of roasts and options that depend on color measurement for quality and consistency.
Image source: Flickr user trophygeek

Using light absorption to measure caffeine levels

Spectrophotometers use light absorption to measure wavelengths that are transmitted through a solution. When measuring the caffeine content in coffee, the molecules in the sample will absorb light at different wavelengths within the color spectrum, providing information that can then be used as quantifiable data for determining the concentration of caffeine. The ability to generate accurate light absorption measurements of the caffeine levels in decaffeinated coffee bean batches is essential for reducing the health risks in sensitive consumers by “preventing inconsistent caffeine levels among available ‘decaf’ blends.”

coffee beans light absorption
Light absorption is used to quickly and accurately measure caffeine levels in sample batches.
Image Source: Flickr user babbagecabbage

The FDA (Food and Drug Administration) requires coffee producers to reduce caffeine content to only 25 parts per million for decaffeinated blends in order to don the “decaf” label.  Light absorption methods of caffeine monitoring can provide instant analysis to indicate when the decaffeination cycle is complete, therefore maximizing production time and efficiency.

Measurement of caffeine in coffee is also important for determining the value of the product. In the article “Measurement of Caffeine in Coffee Beans with UV/vis Spectrometer,” it was reported that “chemical analysis of caffeine in coffee beans is also used as an additional tool for evaluating coffee quality.” However, to the average coffee drinker, many other factors affect the consumer perception of quality.

Other applications of UV spectroscopy for coffee measurement

The quality of coffee is dependent on many different factors, but color perception is often the prime component of consumer choice. Coffee color can change drastically depending on roasting time, growing location, and whole bean verses ground varieties. Light absorption measurement provides a valuable tool in the assessment of consistency due to these variables. Using spectrophotometers during the roasting process can help manufacturers determine when to stop to roasting process in order to obtain the highest quality of color for consumer satisfaction. Roasting times also vary depending on desired color for light, medium, or dark roasts and require color measurement tools that are quick, accurate, and easy to use. Human perception is often subjective and can vary, therefore using proper instrumentation can alleviate errors and increase production time and consistency.

ground coffee light absorption
Roasting times vary depending on desired color. Spectrophotometers provide objective and accurate measurements for real-time results.
Image Source: Flickr user Breville USA

Instrumentation options and differences

Light absorption analysis of coffee is made possible with an assortment of instrumentation options ranging from large scale machines to easy to use hand-held portable units. Spectrophotometric technology has advanced rapidly and now provides many options coffee manufacturers to measure the color and quality of their products. At HunderLab, we have created instrumentation that is specifically adapted for coffee measurement analysis. The ColorFlex EZ Coffee Spectrophotometer is designed to measure the reflected color of coffee grounds with the ability to analyzed freeze dried and instant varieties as well. Our product design is compact and easy to use, plus it is backed by unrivaled customer support and satisfaction. We are a trusted name in color measurement and spectrophotometers, providing services around the world. Contact Hunterlab to learn more about how color measurement can help you improve coffee production and quality today.

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