Tea Fingerprinting: Combining Chromatography and Spectrophotometry for Quality Analysis

After being a habitual coffee drinker for most of my life, I finally switched out my mid-morning cream and sugar-saturated cup for a healthier alternative: tea. Apparently I am joining the already millions of people who consume tea on a daily basis, making tea second only to water in popularity around the globe. Not only does tea come in a variety of choices, but high quality tea boasts numerous health benefits as well. Tea fingerprinting is the most widely used method for analyzing the quality of tea through chromatography and spectral analysis. Color, flavor, and health benefits are all related to quality, and new advancements in colorimetric technology offer better ways to measure these traits and provide quantifiable data through the use of spectrophotometers.

Chromatographic fingerprint analysis is used as a tool for determining the quality of tea products.
Image source: Florin Gorgan via wikimedia.o

The processes of tea production and evaluation

In his book Tea in Health and Disease Prevention, Victor R. Preedy explains, “In the tea manufacturing industry, experienced tea experts are needed to assist buyers with the evaluation of tea aroma and quality. This method of tea evaluation, however, lacks reliability and accuracy. Therefore, a number of tea discrimination methods have been developed that help and guarantee the fairness on the tea trade worldwide.”

Chromatography is currently the most widely used method of tea fingerprint evaluation, but color offers another a major resource for quality analysis in tea products. Temperature, production processes, and storage methods, as well as the variation between dry leaves and tea soup all affect the color of tea at various stages of production. These changes make analysis important during every step of the tea manufacturing process and must be continuously monitored to ensure quality and consistency.

Tea is available in a variety of color options and color variations occur readily between major producers and processing methods.
Image Source: Flickr user Maks Karochkin

Chromatography vs. visual spectral analysis

Chromatography involves a separation process that is highly effective for sample evaluation; however it requires expensive equipment and involves complex training for use. New studies have found that color measurement analysis is equally effective but does not require expendable resources and can be performed at relatively low costs. Improvements in colorimetric methods have opened the door to visual spectral analysis for tea fingerprint evaluation. In the scholarly article, “Tea Fingerprinting By Using Visible Spectral Analysis,” this insight is offered:

“Promising evidence had been reported on the correlations among levels of chemical components existed in tea soup and colorimetric parameters [5]. Besides, former report described the biochemical reactions occurred during tea production process and the associated color change [2]. Also, there were other studies demonstrated the impact of various environmental or chemical factors on the resultant color of tea leaves as well as tea soup [7-9]. These works provided solid evidence on the feasibility of quality control by analyzing the color exhibited by tea leaves and tea soup.”

Spectrophotometric evaluation offers a cost effective option for quality analysis of teas through every processing stage.
Image Source: Flickr user Fred Jala

Black tea is currently the only variety of tea that requires specific standardize regulation, however there is work toward developing methods for grading and supportive evaluation of health benefits of other varieties through quantitative analysis. Spectrophotometers have become a new and affordable alternative to chromatography for product evaluation and may soon change the way we measure the quality of teas.

The role of spectrophotometers in quality analysis

In the past, tea fingerprinting relied solely on chromatography techniques for quality analysis, but spectrophotometers now provide a more cost effective option for tea fingerprint analysis. Spectrophotometers are easy to use and come in a variety of options for portability and durability, making them a prime choice for continual monitoring of color and quality.

HunterLab offers a variety of color measurement options that are suitable for this application. We offer affordable instrumentation that can be used with a variety of samples and throughout all stages of development and processing. Our equipment provides accurate and reliable results for maintaining product consistency and quality and is backed by unsurpassed customer support. Contact HunterLab today for more information on using color measurement to meet your quality control needs.