Naslov
Extraction and stabilisation of quercetin from yellow onion skin

Autori
Osojnik Črnivec, Ilja Gasan ; Skrt, Mihaela ; Šeremet, Danijela ; Komes, Draženka ; Poklar Ulrih, Nataša

Kolaboracija
Biotechnical Faculty, University of Ljubljana, Slovenia ; The Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CipKeBiP), Ljubljana, Slovenia

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
BOOK OF ABSTRACTS - 10th International Congress of Food Technologists, Biotechnologists and Nutritionists / Komes, Draženka ; Vidaček Filipec, Sanja ; Voučko, Bojana ; Šeremet, Danijela ; Marković, Ksenija ; Rumora Samarin, Ivana - Zagreb : Hrvatsko društvo prehrambenih tehnologa, biotehnologa i nutricionista, 2022, 218-219

Skup
10th International Congress of Food Technologists, Biotechnologists and Nutritionists

Mjesto i datum
Zagreb, Hrvatska, 30.11.2022. - 02.12.2022

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
yellow onion skin ; liposomes ; quercetin

Sažetak
Onions (Allium cepa L.) are one of the most harvested fresh vegetables in the EU, with annual production of residues amounting to about 0.5 M tonnes. Onion skin is rich in flavonoids, especially quercetin, but this biomass is usually discarded during processing. These bioactive compounds could be useful for a protective nutrition or as a technical ingredient in food products. This research examined the stability and degradation of free quercetin, green solvents and procedures for the extraction of quercetin from onion peel, as well as stabilisation through liposomal encapsulation. Initial stability of quercetin was examined by UV-Vis spectrometry and antioxidant capacity determination (pH from 2 to 8, temperatures from 25 to 90 °C, exposure time up to 24 hours). At ambient conditions and pH 2 in the dark, the levels of quercetin were relatively well maintained in the initial hours of observation, and markedly depleted after 24 h. Higher pH values (> 7.4) and/or light at higher temperatures (> 60 °C) further accelerated the depletion profiles. Further metabolomic screening showed additional information regarding metabolite formation. Ethanol (70 %) extracts of onion peel were used in further examination and quercetin was monitored by HPLC-PDA. Either quercetin standard or onion peel extract were entrapped in liposomes, at different ratios between the standard/extract and liposomes (1:20 and 1:100). The greatest encapsulation efficienty was observed for quercetin standard prepared with liposomes in ratio 1:20 (roughly 90%), while encapsulation efficiency of quercetin from onion peel extract, was lower (roughly 75%) at the same conditions. The stability of encapsulated quercetin was followed for 30 days using HPLC- PDA. Over 80 % stabilisation of quercetin in yellow onion skin was achieved with liposomal preparation. Furthermoer, the interactions between quercetin and lipids were characterised by differential scanning calorimetry, indicating that quercetin interacted mainly with the polar headgroup regions of the liposomal bilayer. Onion peel thus presents a rich source of quercetin which could be employed in the formation of stable functional dosage forms. Liposomal encapsulation offers an approach to overcome quercetin degradation.

Izvorni jezik
Engleski

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