Sample Preparation. After removal from the storage
chamber and separation from damaged or decayed fruit, an
approximately 25 g subsample of whole fruit was immediately
homogenized in 10 volumes of a cold solution of 3% (w/v)
metaphosphoric acid, 8% glacial acetic acid (v/v), in water (pH
1.5) for 1 min, using a Waring Blender (Waring Products, New
Hartford, CT). Because of their large size, strawberry fruit
were first cut in half and one-half was immediately ground as
described above. A uniform suspension of homogenate was
stored at -70 °C for ascorbate analysis. Fruit extracts for
phenolic analysis were obtained by grinding fruit (1:2 w/v) for
2 min in hot methanol, using a Vitis Homogenizer (The VirtisCo., Gardiner, NY). Fruit extracts for anthocyanin analysis
were obtained by grinding fruit (1:10) in methanol acidified
with 0.01% HCl (v/v) for 2 min, followed by storage at room
temperature in the dark for at least 12 h. Phenolic and
anthocyanin extracts were stored at -40 °C prior to analysis.
The methanolic extract obtained for phenolic analysis was also
used for measurement of antioxidant capacity by drying an
aliquot of extract under vacuum at 30 °C and resolubilizing
in water. Depending on the fruit, aqueous extracts were
further diluted between 100- and 400-fold prior to the antioxidant
capacity assay.