S. Guyot et al., Thiolysis-HPLC characterization of apple procyanidins covering a large range of polymerization states, J AGR FOOD, 49(1), 2001, pp. 14-20
Procyanidins from the cortex of two cider apple varieties (Malus domestica;
Kermerrien and Avrolles) were extracted by solvents. After a solid-phase e
xtraction step, they were fractionated by normal-or reversed-phase HPLC at
the semipreparative scale to obtain a series of purified fractions covering
a wide range of polymerization states. Freeze-dried fractions were charact
erized by reversed-phase HPLC following thiolysis. Elution on normal-phase
HPLC gave oligomeric procyanidins fractions with (DPn) over bar (average de
gree of polymerization) values varying from 2 to 8, whereas polymeric fract
ions ((DPn) over bar values varying from 7 to 190) were obtained by reverse
d-phase HPLC. Constitutive units were mainly (-)-epicatechin with a proport
ion above 95% for all fractions. Thiolysis yields were wholly homogeneous w
ith an average value of 75%, which indicates that the efficiency of the rea
ction did not depend on the polymerization state of the procyanidin fractio
ns.