Biology Reference
In-Depth Information
storage, or by an easier extractability of ellagic acid from processed
products due to degradation of cell structures. In the commercial berry
jams investigated by Koponen
et al
. (2007), the relative amount of free
ellagic acid derivatives was as high as 11% in strawberry jam, in contrast
to 3% in raspberry jam. This may suggest that during strawberry
processing, ellagitannins are decomposed and converted to ellagic acid
more easily than during raspberry processing.
Fig. 8.4 Cloudberry (
Rubus chamaemorus
), an arctic
delicacy and an excellent source of ellagitannins. This
boreal plant grows wild in the circumpolar regions. Photo:
Arctic Flavours Association, Finland.
8.2.3 Pomegranate juice
Pomegranate (
Punica granatum
) fruits are
ancient medicinal foods, which have been used
for centuries in folk medicine. They are
consumed fresh and as juice, which is an excellent source of
ellagitannins. Commercial juices contain gallagyl-type ellagitannins,
including punicalagin isomers (1500-1900 mg/L), undefined
hydrolyzable tannins (400-500 mg/L), and ellagic acid and its glycosides
(120-260 mg/L) (Gil
et al.
, 2000). Punicalagins, ellagitannins in which
gallagic and ellagic acids are linked to a glucose molecule, are abundant
in pomegranate peel. Punicalagin isomers and ellagic acid derivatives are
not present in the aril juice, but during industrial juice processing, they
are extracted from the husk and released in large quantities into the juice.
8.2.4
Grape juice and wine
Muscadine grapes (
Vitis rotundifolia
) are cultivated in southeastern U.S.
and are consumed fresh or used for juice and wine production. Unique
among
Vitis
species, muscadine grapes contain ellagitannins and ellagic
acid derivatives (Lee and Talcott, 2004, Lee
et al.
, 2005). In three red
and white cultivars, the following concentrations were detected: free
ellagic acid, 14-50 mg/kg, ellagic acid glycosides, 44-87 mg/kg, and total
