Effect of Solvents and Solid-Liquid Ratio on Caffeine Extraction from Cote d'Ivoire Kola Nuts (Cola nitida)

Caffeine is a natural substance of plant origin very present in our culture and used for its stimulant properties on the nervous system. Is found in various forms, especially in drinks such as coffee, tea, energy drinks, as well as pharmaceuticals and food supplements. The aim of this work was to determine caffeine content from two varieties of kola nuts (Cola nitida) by using UV spectrophotometric method and examine the effect of extraction solvent and solid-liquid ratio for the optimal caffeine extraction from kola nuts. Kola nuts were collected in October 2013 to March 2014 in two regions of Cola nitida plantation in Cote dIvoire. Harvested kola nuts were transferred to the laboratory until used in the experiments. Nuts were divided into six groups according to their variety (traditional or improve) and morphotype (red, white, purple and pink). After drying and powder processing, six solvents (Water, Ethanol 100 %, Methanol 100 %, methanol 50 % in water, ethanol 50 % in water and Water/Ethanol/Methanol (WEM) (2/1/1, v/v/v) and five solid/liquid (w/v) ratio (1/100, 3/100, 4/100, 5/100 and 6/100) were used for evaluate caffeine content and determine the effect of each parameter. Extraction was made by stirring using an electronic shaker. Results showed that extraction solvent and solid/liquid ratio had significant effect on caffeine content. The optimal condition were obtained with WEM solvent, solid/liquid of 3/100 and stirring at 150 trs/min applied for 20 hours. Caffeine content observed under these conditions was ranged between 1.84 % and 2.56 %. In general, contents of improved nuts are higher than that of traditional nuts. The extractive capability of kola nuts caffeine is considerably depended on the type of solvent and solid/liquid ratio. Kola nuts are a good source of caffeine and therefore can be used by beverage producers who are interested in other sources of caffeine other than the common Coffea canephora. The choice of a suitable solvent (non-toxic) is necessary in the context of potential food uses.