Decaffeination Of Coffee Beans Research Articles

Lakes of liquid CO 2 in the deep sea

The thought of liquid CO2 conjures up different things to different folks: perhaps the decaffeination of coffee beans, perhaps the recently popularized “green” method for dry cleaning, or even phase diagrams that occupied a part of one's life in past chemistry classes. What it does not conjure up is a subsurface lake at the bottom of the ocean, a lake with abundant living microbes, as reported in this issue of PNAS by Inagaki et al. (1). These authors discovered such a place near the Yonaguni Knoll in the Okinawa Trough at a depth of ≈1,400 m. The description in both words and video (see supporting movie 1 in ref. 1) is quite striking. First, because liquid CO2 at this depth is less dense than water (2, 3), so that such a lake should not be present. Second, because this is a phenomenon that few of us have ever seen, movie 1 in ref. 1 reveals a flowing stream of liquid CO2 that seems almost surreal.

Determination of serotonin released from coffee wax by liquid chromatography

A simple hydrolysis and extraction method was developed for the release of serotonin (5-hydroxytryptamine) from a coffee wax sample obtained from decaffeination of coffee beans. The recoverable amount of serotonin was determined by reversed-phase high-performance liquid chromatography with gradient elution and UV detection, using the standard addition method. Different type of basic deactivated chromatographic columns were used for the separation.

Diffusion phenomena during the decaffeination of coffee beans

The coffee bean behaves with respect to the diffusion of caffeine almost as perfectly as a spherical model system. This behaviour is a consequence of at least two opposite effects—the taking up of solvent and the water loss. The overall change of the diffusion coefficient caused by these factors remains, however, small compared with the shifts brought about by the parameters investigated: water content and temperature. It is therefore reasonable to express the effects of these variables by using a single quantity, namely, the average apparent diffusion coefficient which, for Columbia and Robusta coffee and at optimal experimental conditions, lies in the range 0·5–1·3.10 −6 cm 2 sec −1.

Diffusion phenomena during the decaffeination of coffee beans*

SummaryThe diffusion of caffeine in green coffee beans was investigated at atmospheric pressure using dichlormethane as a solvent.The diffusion coefficient of caffeine was determined as a function of temperature and water content of the beans. the mathematical treatment was based on Fick's second law of diffusion applied to a spherical model.The apparent diffusion coefficients are in the range of 0.2‐1.1. 10−6 cm2 sec−1.