In the second year, the concentration of residual phenolics
resulting from O. crenata extract present in treated sweet cherry
tissue as well as in washing water, was evaluated on lots of fruit
prepared ad hoc for such trials. Fruit were selected as previously
described, placed in plastic trays (10 fruit per tray), and treated as
above with O. crenata extract at the highest (4) concentration.
The analysis of phenolic compounds in fruit after treatment before
and after storage, in treated fruit after washing, as well as in
washing water, was performed in triplicate. Thirty grams of sweet
cherry fresh tissue, taken from 10 fruit of each replication, were
homogenized and refluxed (twice for 1 h) with methanol. After
filtration through Whatman Grade 1
filter paper, methanolic
extracts were concentrated under reduced pressure at 35 C and
the residue suspended in 50% (v/v) aqueous methanol,
filtered
through a 45 mm pore size membrane
filter, and used for HPLC
analysis. As the washing water analysis, 30 fruit, three for each tray,
were weighed, placed in a
flask, covered with about 500 mL of
distilled water, and shaken at 60 rpm for 30 min. The washing
water was recovered and evaporated to dryness under reduced
pressure at 35 C, using a rotary evaporator. The residue was
dissolved in 10 mL of 50% (v/v) aqueous methanol,
filtered as
reported above, and used for HPLC analysis.