Effect of Some Thermal Processing Methods on the Caffeine Content and Colour Absorbance of Kola Nuts

Abstract

Fresh kola nuts (Cola nitida) were thermally processed (blanched, boiled and roasted) for different periods of time (5, 10, 15 and 20 minutes respectively) at different temperatures (65, 75, 85 and 95oC). Boiling was done at 80oC while roasting was at 108.5oC, and steam blanching duration was 5, 7.5, 15 and 20 seconds respectively. The nuts were then diced, grated and stored for subsequent analysis in a Haier thermocool freezer. Subsequent study of the effects of the various treatments on the proximate and the caffeine contents of the kola nuts revealed that increase in temperature and duration of boiling resulted in product with lower caffeine content. However, product with the lowest caffeine content was produced during steam blanching at 108.5oC for 5 seconds. The various treatments also produced kola nut powder with darker colour but to varying degrees of darkness. These results are discussed in relation to the quality of kola nut powders for different product applications.