May 7/Science Letter -- According to recent research from Seoul, South Korea, "Green tea has been widely consumed for its mild flavors and its health benefits, yet caffeine in green tea has been a limitation for those who want to avoid it. The limitation brought increase in need for decaffeinated products in the green tea market."

"Most of the conventional decaffeination techniques applied in food use organic solvents. However, the supercritical carbon dioxide fluid extraction (SC-CO2) method is gaining attention as one of the future decaffeination methods that overcomes the problems of conventional methods.

"The purpose of this study was to identify sensory characteristics of decaffeinated green teas applied with SC-CO2 method and to observe the relationship with consumer acceptability to elucidate the potentiality of applying SC-CO2 technique in decaffeinated green tea market. Descriptive analysis was performed on eight samples: green teas containing four caffeine levels (10%, 35%, 60% and 100%) infused at two infusing periods (one or two minutes). It was found that the SC-CO2 process not only reduced caffeine but also decreased some important features of original tea flavors.

"Two groups were recruited for consumer acceptability test: one (GP I, N=52) consuming all types of green teas, including hot/cold canned teas; and the other (GP II, N=40) only consuming the loose type. While GP II liked original green tea the most, GP I liked highly decaffeinated green teas," wrote S.M. Lee and colleagues, Ewha Womans University.

The researchers concluded, "Although the SC-CO2 method had limitations of losing complex flavors of green teas, it appeared to have future potential in the decaffeinated green tea market within or without the addition of desirable flavors."

Lee and colleagues published their study in the Journal of Food Science ("Sensory Characteristics and Consumer Acceptability of Decaffeinated Green Teas." Journal of Food Science, 2009;74(3):S135-S141).

For additional information, contact K.O. Kim, Ewha Woman's University, Dept. of Food Science & Engineering, Seoul 120750, South Korea.

From the May 11, 2009, Prepared Foods E-dition