In the present investigation, enzymatic de- bittering of grapefruit juice using lyophilized naringinase produced by P. purpurogenum with respect to enzyme concentration 0.25, 0.5 and 1g/100ml juice and temperature (25, 30 and 40°C) and time of incubation (1, 2 and 4 h) was optimized. In all three independent variables, enzyme concentration, temperature and time of incubation, were varied at three levels. In addition to that, controls were maintained for each set. From the results obtained (Table 1, Figures 1-3) it can be seen that when all the parameters i.e. the enzyme concentration, temperature and time of incubation were varied, there is a decrease in the naringin content. Maximum decrease of naringin (about 74%) was obtained at naringinase concentration of 100 U/100ml juice, with incu- bation at 40°C for 4 h.