3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
Chasla varieties have the highest (280.3 ± 1.8), and respectively
the lowest (86.18 ± 3.1) TEAC values. Chasla have also
the lowest ORAC value (100.7 ± 1.8).
The antioxidant activities determined by TEAC and
ORAC showed a very good correlation (r = 0.99). A good
correlation was obtained also for ORAC and DPPH assay
(r = 0.97). Both assays are based on Trolox (a water soluble
derivative of vitamin E) equivalents, although the ORAC
assay represents a hydrogen atom transfer reaction mechanism
and the TEAC assay represents a single electron transfer-based
method 5 . Ou et al. (2002) reported no correlation
between the FRAP and ORAC techniques among most of 927
freeze and dried vegetable samples, whereas these methods
reveald a hight correlation in blueberry fruit (Connor et al,
2002) 3,4 . Similarly, Awika et al, 2003 observed high correlation
between ABTS, DPPH, ORAC among sorghum and its
products 2 . DPPH assay values shows significant differences
between the flavanol richest Merlot sample (1,140 ± 0.08) and
the flavanol poorest Chasla sample (67.2 ± 1.1) respectively.
The amounts of total phenolic compounds were of the same
order of magnitude among the studied grape seed varieties
from 423 mg GAE 100 g –1 DW to 651 mg GAE 100 g –1 DW
material (Table I). This is most probably due to the presence
of the same type of phenolic compounds in the samples 5 .
Conclusions
The flavanols contribute to the antioxidant activity of
grape seed extracts. Ranking of antioxidant capacity was higly
consistent across the different methods used, obtaining
the same following ranking from the varities of the grapes
seed extracts tested:
Merlot> Feteasca> Mustoasa > Chasla
This study confirms also the correlation between ORAC,
DPPH and TEAC assays, their values being proportional with
phenolic compounds contents.
This work has been supported by CNCSIS TD, 2006–
2008, Romanian Research Project.
s623
Fig. 1. The antioxidant activity of grape seed extracts determined
by TEAC, ORAC, DPPh assays
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