The yields of extraction by various solvents
decreased in the following order: 50% aqueous acetone > 50%
aqueous ethanol > 75% aqueous methanol > 50% aqueous
methanol > 75 % aqueous acetone > 75% aqueous ethanol >
100% methanol > RO water > 100% ethanol > 100% acetone. It
can be seen that the extraction yield of pure methanol
(26.06%) is higher than that of pure ethanol (17.03%) and pure
acetone (12.33%). This shows that the extraction yield increases
with increasing polarity of the solvent used in
extraction. It can also be found that the yield of the water
extract (25.58%) is only slightly less than that of the pure
methanol extract (26.06%), whereas the yield of aqueous solvent
extract (from 26.08 % for 75% aqueous ethanol to 33.67 %
for 50% aqueous acetone) is higher than that of the pure solvent
extracts (from 12.33% for acetone to 26.06% for methanol).
These results indicate that increasing the water
concentration in the solvent enhances extraction yield.
Compounds other than phenolics may have been extracted
and contribute to higher yield. This may be attributable to the
higher solubility of proteins and carbohydrates in water and
methanol than in ethanol and acetone [20].