1 research outputs found
Characterization of Ellagitannins, Gallotannins, and Bound Proanthocyanidins from California Almond (Prunus dulcis) Varieties
Extractable and bound proanthocyanidins and hydrolyzable
tannins
were characterized in Nonpareil, Carmel, and Butte almond varieties
from California, with <i>n</i> = 3 samples/variety. Bound
proanthocyanidins were recovered from extracted defatted almond residue
by hydrolysis with 4 N sodium hydroxide and represented 3–21%
of the total proanthocyanidin content among varieties. The bound proanthocyanidins
were recovered primarily as monomers and dimers. In contrast, acid
hydrolysis of extracted almond residue did not yield bound proanthocyanidins.
Hydrolyzable tannins were characterized in aqueous acetone extracts
of defatted almond using two-dimensional TLC and further quantitated
by HPLC following acid hydrolysis. Almond hydrolyzable tannin content
was 54.7 ± 2.3 mg ellagic acid and 27.4 ± 7.3 mg gallic
acid per 100 g almond among varieties. The tannin contents of Nonpareil,
Carmel, and Butte almond varieties were not significantly different.
Thus, bound proanthocyanidins and hydrolyzable tannins significantly
contribute to almond polyphenol content