Abstract:
Ethanol extracts of mangosteen fruit rind contain high antioxidant activity that is heat
labile. Drying of ethanol extracts containing antioxidant activity ideally is carried out at
low temperatures using a vacuum freeze dryer. In the absence of a vacuum freeze dryer
other methods must be used, such as oven drying but at temperatures with minimal loss
of the antioxidant activity. To evaluate the effects of the drying process, the antioxidant
activities of mangosteen fruit rind 30% ethanol extracts before and after oven drying at
60oC was compared to each other. Dried powdered mangosteen fruit rind was incubated
in 30% ethanol for 8 days at 40ºC and 100 rpm in a shaking incubator. After incubation,
the mixture was filtered to separate the ethanol extract from the remaining solids. The
ethanol solvent from the filtered extract was evaporated by rotary vacuum evaporation
at 50oC, and the semi-dried residue was further oven dried at 60oC to constant weight.
The antioxidant activity of the semi-dried extract residue and oven dried extract was
analyzed using the 2,2 diphenyl-1-picrylhydrazyl (DPPH) method. The results showed
that the IC50 value of the antioxidant activity from mangosteen fruit rind 30% ethanol
extract before the drying process was (42.78±1.54) μg/mL, and after the drying process
was (21.30±2.29) μg/mL. Unpaired student t analysis to compare the average IC50
values of the 30% extracts before and after drying showed that there was a significant
increase (p<0,05) in the antioxidant activity after the 60oC oven drying process.
