Extractions
Fruit extracts for total phenolic content and
hydrophilic antioxidant activity analyses were prepared
following the method of Swain and Hillis (1959), with
some modifications. Three grams of guava tissue (flesh
and peel) was mixed with 25 ml methanol (MeOH)
and homogenized using an Ultra-Turrax homogenizer
(T25, Ika Works, USA). The homogenates were kept
at 4°C for 12 hours and then centrifuged at 15,000 rpm
for 20 minutes using a vacuum microcentrifuge
(Beckman, J2-21, Beckman Instruments, USA). The
supernatant was recovered and stored at -20°C until
assayed. The pellet was redissolved with 20 ml of
dichloromethane and homogenized for lipophilic
antioxidant activity analysis. The homogenates were
centrifuged at 15,000 rpm for 20 minutes. The
supernatant was recovered and stored at -20°C until
assayed.