3. Results and discussion
3.1. Total phenolic contents of sunflower florets in different
extracts
The total phenolic contents in various extracts of ray florets and
disc florets were determined by using the Folin–Ciocalteu method
(Fig. 1). The solvent efficiency in the extraction of phenolic compounds
from both ray florets and disc florets was in the order of
aqueous alcohols > water > ethyl acetate. For ray florets (Fig. 1A),
the highest phenolic content was observed in the extract with
90% (v/v) aqueous methanol (2787.2 mg GAE/100 g dw) and no significant
difference (p > 0.05) was found among the values with
other aqueous alcohols. For disc florets (Fig. 1B), no significant
difference (p > 0.05) was observed among the total phenolic content
(2935.7–3045.2 mg GAE/100 g dw) in extracts with 50% (v/v)
methanol, 90% (v/v) methanol, and 50% (v/v) ethanol, but these values
were significantly (p < 0.05) higher than that with 90% (v/v)
ethanol (2309 mg GAE/100 g dw). Taken the polarities of used solvents
into consideration, it has been revealed that phenolics from
sunflower florets are more extractable by solvents with medium
polarity. Similar results were previously reported by Akowuah et al.
(2005) and Turkmen et al. (2006).