Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Food Science and Technology

Major Professor

J.L. Collins

Committee Members

Ann F. Draughon, J.R. Mount, Hugh O. Jaynes, Dennis E. Deyton


The objectives of this research were to determine the most appropriate treatments and conditions for extracting caffeine from guaraná (Paulinia cupana var. sorbilis (Mart.) Ducke) seed and to determine the most effective solvents to accomplish the extraction.

Seeds of guaraná, a Brazilian fruit, were prepared for extraction of caffeine. The procedures for preparation included: grinding seeds into a meal, rehydrating with acid or alkaline solutions, and steaming. Extraction was accomplished with single-stage (solvent was not replaced with fresh solvent during the extraction period) or multiple-stage (solvent was replaced with fresh solvent after specified periods of time) processes and with or without agitation. The solvents were ethanol-water mixtures, methylene chloride, and ethyl acetate.

Seeds of the two drying methods, traditional (TD) and solar (SD), were analyzed. TD seeds contained the greater amount of all proximate components, except carbohydrates, and the minerals: calcium, potassium, cooper, and iron. TD and SD seeds contained 4.07% and 4.40% caffeine, respectively. Fifteen volatile components from the methylene chloride extract were identified tentatively. With one exception, guaraná leaves contained, at most, only traces of caffeine. Rehydration and reduction of the guaraná materials and agitation increased the extraction of caffeine significantly (0.05 level). Greater amounts of caffeine were extracted from alkaline treated seed and ground material.

The following conditions were found to be the most efficient for extracting caffeine: rehydrate the guarana material with alkaline solution to approximately 40% moisture, use methylene chloride as the solvent, apply constant agitation, and replace the solvent with fresh solvent after specified periods of time.

Coefficients of diffusion for caffeine were determined for six sets of conditions. The were found to be similar to those reported for coffee.

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