As an initial step, apple samples were analyzed by LC–MS
QTof and HPLC–DAD systems. Fifteen different polyphenolic
compounds were identified as function of their
retention times compared with the standard compounds in
HPLC analyses and as function of their mass fragmentation
compared with those of the standard compound during
LC–MS QTof analyses. Qualitative analyses obtained
by LC–MS QTof methods and by HPLC are summarized
in Tables 2 and 3. Three hydroxycinnamates were detected:
p-coumaroylquinic acid, chlorogenic acid and cryptochlorogenic
acid. The compound that had a [M–H]− at m/z 337
was identified as p-coumaroylquinic acid. Chlorogenic
acid and cryptochlorogenic acid have a characteristic mass
spectral data as is produced on [M–H]− at m/z 353 and
the fragmentation of the negatively charged molecular ion
([M–H]−) at m/z 191 and 137, respectively. Five flavan-
3-ols were detected: (+)-catechin, (−)-epicatechin and procyanidins
B1, B2 and C1. In the presence retention time (Rt
)
at 2.81 min, λmax for 280 nm was identified as (+)-catechin
with the fragmentation of the negatively charged molecular
ion ([M–H]−) at m/z 289. Procyanidin B1 and B2 (λmax)
275 nm had a [M–H]− at m/z 578, but the retention time
for procyanidin B1 was Rt
at 2.47 min and for B2 was (Rt
)
5.47 min. The compound with (Rt
) 5.98 min, λmax 280 nm