One gram of peel tissue powder was extracted in 1.5 mL of ethanol:acetone
(7:3, v/v) for 1 h at 37 C. The homogenate was centrifuged
at 13,000g for 10 min at 20 C. The supernatants were
stored at 20 C until used for antioxidant assays.
TP content. TP was determined using the Folin–Ciocalteu
method. In a 10 mL glass tube, 7.9 mL distilled water, 0.1 mL pear
extract and 0.5 mL Folin–Ciocalteu reagent (1:1 with water) were
added and mixed. After exactly 1 min, 1.5 mL of sodium carbonate
(20 g 100 mL1
) was added, and the mixture was mixed and
allowed to stand at 20 C in the dark for 2 h. The absorbance of
each sample was measured at 765 nm, and the TP content was calculated
from a calibration curve, using gallic acid as standard (50–
1000 mg L1
).
TF