EXTRACTION AND SPECTROPHOTOMETRIC QUANTIFICATION OF TOTAL POLYPHENOLIC CONTENT IN ONION
Journal
The Journal "Agriculture and Forestry"
Date Issued
2023-06-30
Author(s)
S. JANKULOVSKA, Mirjana
SOKOLOVSKA, Viktorija
VELKOSKA-MARKOVSKA, Lenche
BOGEVSKA, Zvezda
KARAKASOVA, Ljubica
MANASIEVSKA, Silvana
MISKOVSKA-MILEVSKA, Elizabeta
BABANOVSKA-MILENKOVSKA, Frosina
MARKOSKI, Mile
DOI
10.17707/agricultforest.69.2.17
Abstract
Consumption of food rich in polyphenols such as fruits and vegetables is of
great importance, because it contributes to the prevention of various diseases.
Polyphenols are a group of bioactive compounds which can play significant role
in preventing various health related problems. One of the richest sources of
polyphenols in the human diet is the onion (Allium cepa L.). The main objective
of the present investigation is quantification of total polyphenolic content (TPC)
in the Macedonian local population of onion. A various organic solvents were
tested (methanol, ethanol, ethyl acetate and acetone) and their different
concentrations (20, 40, 60 and 80%) in order to establish optimum solvent
concentration for extraction of polyphenols from onion. Time for extraction was
another important parameter which was examined as well. TPC was determined
by UV-Vis spectroscopy in accordance with the Folin–Ciocâlteu assay, using
gallic acid as a reference standard. The results were expressed as mg gallic acid
equivalents GAE/100 g fresh onion. The highest polyphenolic level was
determined in 60% methanol (38.81±0.39 mg GAE/100 g), while lower total
polyphenolic content was found in the ethyl acetate extracts (27.10±0.35 mg
GAE/100 g). Regarding the time for extraction, the highest content of total
polyphenols in onion was obtained during extraction of 120 minutes (37.95±0.63
mg GAE/100 g).
great importance, because it contributes to the prevention of various diseases.
Polyphenols are a group of bioactive compounds which can play significant role
in preventing various health related problems. One of the richest sources of
polyphenols in the human diet is the onion (Allium cepa L.). The main objective
of the present investigation is quantification of total polyphenolic content (TPC)
in the Macedonian local population of onion. A various organic solvents were
tested (methanol, ethanol, ethyl acetate and acetone) and their different
concentrations (20, 40, 60 and 80%) in order to establish optimum solvent
concentration for extraction of polyphenols from onion. Time for extraction was
another important parameter which was examined as well. TPC was determined
by UV-Vis spectroscopy in accordance with the Folin–Ciocâlteu assay, using
gallic acid as a reference standard. The results were expressed as mg gallic acid
equivalents GAE/100 g fresh onion. The highest polyphenolic level was
determined in 60% methanol (38.81±0.39 mg GAE/100 g), while lower total
polyphenolic content was found in the ethyl acetate extracts (27.10±0.35 mg
GAE/100 g). Regarding the time for extraction, the highest content of total
polyphenols in onion was obtained during extraction of 120 minutes (37.95±0.63
mg GAE/100 g).
Subjects
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