Vsebnost kvercetina v rdeči, rumeni in beli čebuli (Allium cepa L.)

Štrumbelj, Erna (author), Poklar Ulrih, Nataša (mentor)

V okviru diplomskega dela smo določali vsebnost kvercetina v jedilnem in odpadnem delu rdeče, rumene in bele čebule ter njihovo antioksidativno aktivnost (AOA). Ekstrakte smo pripravili v dveh različnih topilih, in sicer v 70 % etanolu in v destilirani vodi. Vsebnost kvercetina smo določili z metodo tekočinske kromatografije visoke ločljivosti (HPLC). Antioksidativno aktivnost smo določili spektrofotometrično s pomočjo metode DPPH• (2,2-difenil-1-pikrilhidrazil radikal). Velja, da večja masa ekvivalenta troloxa/100 mg liofiliziranega vzorca pomeni večjo antioksidativno aktivnost. Pričakovano smo v odpadnem delu čebule določili večjo vsebnost kvercetina kot v jedilnem delu. Največjo vsebnost kvercetina smo tako za jedilni kot za odpadni del določili v rdeči čebuli (za jedilni del 0,0121 ± 0,0001 mg ekvivalenta kvercetina/100 mg liofiliziranega vzorca (ekstrakcija s 70 % etanolom) oziroma 0,0291 ± 0,0002 mg ekvivalenta kvercetina/100 mg liofiliziranega vzorca (ekstrakcija z destilirano vodo) in za odpadni del 1,5266 ± 0,0025 mg ekvivalenta kvercetina/100 mg liofiliziranega vzorca (ekstrakcija s 70 % etanolom) oziroma 0,0981 ± 0,0005 mg ekvivalenta kvercetina/100 mg liofiliziranega vzorca (ekstrakcija z destilirano vodo)). Na podlagi teh rezultatov sklepamo, da največ kvercetina vsebuje rdeča čebula. Večjo antioksidativno aktivnost smo določili odpadnemu delu različno obarvanih čebul, pri čemer je največjo antioksidativno aktivnost pokazal odpadni del rdeče čebule (3,738 ± 0,056 mg ekvivalenta troloxa/100 mg liofiliziranega vzorca (ekstrakcija s 70 % etanolom) oziroma 2,176 ± 0,040 mg ekvivalenta troloxa/100 mg liofiliziranega vzorca (ekstrakcija z destilirano vodo)).

• Language: Slovenian
• Keywords: čebula, Allium cepa L., rdeča čebula, rumena čebula, bela čebula, čebulni olupki, jedilni del, odpadni del, HPLC, DPPH, kvercetin, antioksidativna aktivnost
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [E. Štrumbelj]
• Year: 2020
• PID: 20.500.12556/RUL-114138
• UDC: 547.972:635.25:543.544.5:543.635
• COBISS.SI-ID: 5171064
• Publication date in RUL: 19.02.2020

Secondary language

• Language: English
• Title: Quercetin content in red, yellow and white onion (Allium cepa L.)

Abstract

The aim of this work was to determine the content of quercetin in the edible and waste parts of red, yellow and white onion, and to determine their antioxidant activity (AOA). The extracts were prepared in two different solvents, 70% ethanol and distilled water. Quercetin content was determined by the high-performance liquid chromatography (HPLC). The antioxidant activity was determined spectrophotometrically using the DPPH• (2,2-diphenyl-1-picrylhydrazyl radical) method. A higher mass of trolox equivalent/100 mg lyophilized sample means a higher antioxidant activity. As expected, a higher content of quercetin was determined in the waste part of the onion. The highest content of quercetin was determined in the edible and waste part of red onion (0,0121 ± 0,0001 mg quercetin equivalent/100 mg lyophilized sample (extraction with 70% ethanol) or 0,0291 ± 0,0002 mg quercetin equivalent/100 mg lyophilized sample (extraction with distilled water) in the edible part and 1,5266 ± 0,0025 mg quercetin equivalent/100 mg lyophilized sample (extraction with 70% ethanol) or 0,0981 ± 0,0005 mg quercetin equivalent/100 mg lyophilized sample (extraction with distilled water) in the waste part). Based on these results, we may conclude that red onion contains the highest amount of quercetin. Higher antioxidant activity was determined in the waste part of differently colored onions, with the highest antioxidant activity in the waste part of the red onion (3,738 ± 0,056 mg trolox equivalent/100 mg lyophilized sample (extraction with 70% ethanol) or 2,176 ± 0,040 mg trolox equivalent/100 mg lyophilized sample (extraction with distilled water)).

• Keywords: onion, Allium cepa L., red onion, yellow onion, white onion, onion peel, edible part, waste part, HPLC, DPPH, quercetin, antioxidant activity