The effect of varying ethanol concentration was investigated using the tightly sealed 231 ml
jam jars with metal screw caps at 5 psi for 5 min as indicated in Table 4. All eleven treatments
provided the results which were significant difference (p ≤ 0.05). The highest level of extracted
anthraquinone concentration of 38.4 ± 0.7 mg/g was achieved with 65%(v/v) ethanol. Aobchey et al.
(2002) reported 15 mg anthraquinone/g of dried root powder. Shotipruk et al. (2004) attained
extraction level of 43 mg/g. However, the extraction level was different from Temiyaputra et al. (2009)
(95.3 ± 0.6 mg/g and 103.2 ± 4.8 mg/g using 80%(v/v) ethanol) who employed air/steam mixture
instead of saturated steam. Further comparison of the pressurized steamer method to two negative
controls, in which the samples of Morinda sp. root powder were soaked in 80%(v/v) ethanol at 30oC
for 5 and 25 min, revealed that the conventional solvent extraction procedure resulted in the lower
level of anthraquinone (12.0 ± 0.1 and 17.0 ± 0.1 mg/g for immersion time of 5 and 25 min,
respectively) than its pressurized counterpart using 80%(v/v) ethanol (30.9 ± 0.5 mg/g) by 1.82 – 2.58
times. The cheapest extraction costs of 1.99 ± 0.02 and 2.01 ± 0.04 baht per mg of extracted
anthraquinone were obtained with 50 and 65%(v/v) ethanol. Furthermore, there was no significant
economical difference (p > 0.05) in using 5 or 95%(v/v) ethanol as extraction solvent in the
pressurized steamer. The utilization of absolute ethanol should be abstained as the extraction cost
was up to 11.6 ± 0.3 baht/mg. The extraction costs of conventional solvent (80%(v/v) ethanol)
extraction procedure were also relatively high with 4.03 ± 0.03 and 2.83 ± 0.01 baht/mg for immersion
period of 5 and 25 min, respectively.