In this study, seed extracts both varieties obtained by using
MeOH:H2O/80:20 were analyzed for the determination of their
total phenolics and flavonoids content. In fact, several studies have
shown that MeOH:H2O/80:20 is an effective solvent mixture for
extracting phenols and flavonoids from the seeds of cereals
(Escarpa & Gonza´ lez, 2001; Zielinski & Kozlowska, 2000) (Fig. 1).
The total phenolics content of seeds was determined by using the
Folin–Ciocalteu method. This study indicated that bitter quinoa
pre-cooking seeds contained a higher amount of phenolics
(86.4 14.1 mg GAE/10 g; p< 0.01) than sweet quinoa ones
(77.216.7 mg GAE/10 g; p <0.01). However, the total phenolics
content in both bitter and sweet quinoa seeds was found to be
higher than that of common cereals, such as wheat (5.6 mg/10 g),
barley (8.8 mg/10 g), millet (13.9 mg/10 g), rye (10.3 mg/10 g), and
sorghum (41.3 mg/10 g) (Ragaee, Abdel-Aal, & Noaman, 2006).
After boiling, data revealed a significant decrease of phenolics
content in both seed varieties: bitter quinoa, 59.4 23.0 mg GAE/
10 g (p< 0.05); sweet quinoa, 28.7 2.8 mg GAE/10 g (p< 0.003).
As regards phenolics content in cooking waters, it was found: bitter
quinoa, 24.2 4.5 mg GAE/10 g (p< 0.001); sweet quinoa,
14.01.0 mg GAE/10 g (p < 0.001). In the case of bitter quinoa, this
result could be attributed to the loss of phenolic in cookingwater. In
fact, the sum of antioxidant activities of post-cooking seeds and
cooking water was similar to that of pre-cooking seeds. As far as
sweet quinoa seeds are concerned, the decrease in their phenolic
content could be due to phenolics breakdown, since the sum of
antioxidant activity of post-cooking seeds and cooking water
consistently differed from antioxidant capacity of pre-cooking seed.
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