THE LIGHT DARK CYCLE OPERATION WITH AN HOUR-SCALE PERIOD ENHANCES CAFFEINE PRODUCTION BY COFFEA-ARABICA CELLS/

The intermittent light irradiation with an hour-scale period is used f or producing caffeine by Coffea arabica cells. Three factors concernin g the light/dark cycle operation such as light intensity, the length o f the cycle (period), and the ratio of the illumination time to the da rk time (light/dark ratio) were investigated to optimize the caffeine production efficiency regarding light consumption. The light/dark rati o of 1/1 enhanced caffeine production, reaching the same level as cont inuous light; thus, the intermittent light irradiation improved the pr oduction efficiency twofold. The production was nor influenced by the period, brit was determined by light intensity regardless of intermitt ent or continuous light irradiation. (C) 1998 Elsevier Science Inc.