Određivanje antioksidativne aktivnosti komine masline metodom izbjeljivanja beta karotena

master's thesis

• Title (english): Determination of the antioxidant activity of olive olive pomace by the beta carotene bleaching method
• Author: Rahela Krajnović
• Mentor: Dubravka Vitali Čepo (mentor)
• Committee member: Dubravka Vitali Čepo (predsjednik povjerenstva)
• Committee member: Lovorka Vujić (član povjerenstva)
• Committee member: Marija Grdić Rajković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of food chemistry); Zagreb
• Defense date and country: 2018-03-22, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract

Komina masline otpad je koji zaostaje nakon proizvodnje maslinovog ulja koji se zbog svoje ekotoksičnosti
ne smije neprocesuiran odlagati u okoliš. Kemijski sastav komine masline karakterizira visok udio
polifenola uz koje se vežu brojni pozitivni biološki učinci. Cilj ovog diplomskog rada bio je po prvi puta
istražiti mogućnosti primjene ekstrakta komine masline kao antioksidansa u β-karoten-linoleat emulzijskom
model sustavu jer taj model bolje reflektira uvjete u sustavima hrane i biološkim sustavima od jednostavnih
kemijskih modela. Princip metode zasniva se na obezbojenju β-karotena peroksiksilnim radikalima linolne
kiseline koje se prati spektrofotometrijski na 450 nm, a prisutnost antioksidanasa iz komine može smanjiti
obezbojenje β-karotena kompeticijskim vezanjem peroksilnih radikala. Ispitana je antioksidativna aktivnost
ekstrakata komine bez i s dodatkom različitih vrsta (β-CD, hidroksipropil-β-CD, nasumično metilirani β-
CD i γ-CD) i koncentracija ciklodekstrina (8 i 16 gL-1) te je kao referentni antioksidans odabran Trolox.
Vrijednosti apsorbancije mjerene su svakih 5 minuta u vremenu od 200 minuta. Za kvantifikaciju rezultata
odabran je parametar R (odgovor) te je za njegovo izračunavanje uzeto vrijeme od 120 min, tj. vrijeme kad
je apsorbancija uzoraka pala na 70% početne vrijednosti. Iz baždarnog pravca ovisnosti R o koncentraciji
Trolox-a izračunati su mg Trolox ekvivalenata (TE) za svaki uzorak. Svi uzorci komine ostvarili su
značajnu antioksidativnu aktivnost. Zaključeno je da vrsta ciklodekstrina korištenog u pripremi suhog
ekstrakta značajno utječe na antioksidativnu aktivnost. γ-ciklodekstrin, nasumično metilirani-β-
ciklodekstrin i hidroksipropil-β-ciklodekstrin pokazali su najpovoljniji i značajan učinak na antioksidativnu
aktivnost ekstrakta komine u β-karoten-linoleat sustavu.

Abstract (english)

Olive pomace is the waste generated from olive oil production and should not be left in unprocessed form
during disposal due to its ecotoxicity. Chemical composition of olive pomace is characterised by high
content of polyphenols that are linked with numerous positive biological effects. The goal of this paper was
to examine the possibilities of using olive pomace extracts as antioxidants in β-carotene-linoleate emulsion
model system for the first time. This model was chosen since it represents more realistically the conditions
in food matrices and biological systems in comparison to simple chemical models. Method is based on β-
carotene bleaching, caused by peroxyl radicals of linoleic acid, which is monitored spectrophotometrically
at 450 nm. Presence of olive pomace antioxidants can reduce β-carotene bleaching by competitive
quenching of peroxyl radicals. Antioxidant activity of pomace extracts formulated with or without different
types (β-CD, hydroxypropyl-β-CD, randomly methylated β-CD and γ-CD) and different concentration (8
and 16 gL-1) of cyclodextrins was examined, and Trolox was used as the referent antioxidant. Apsorbance
was measured in 5 minutes intervals during the 200 min period. Parameter R (response) was chosen for
quantification of results at 120 min, which is the time when apsorbance decreased to 70% of its initial
value. Trolox equivalent (TE) values were calculated for each sample using the calibraton curve of TE
concentration – response dependancy. All samples showed significant antioxidant activity. It is concluded
that the type of cyclodextrin used in dry extract preparation has significant effect on antioxidant activity. γ-
cyclodextrin, randomly methylated β-cyclodextrin and hydroxypropyl-β-cyclodextrin showed most
favorable effect on antioxidant activity of pomace extract in β-carotene-linoleate system.

• Keywords: komina masline; β-karoten-linoleat; antioksidativna aktivnost; ciklodekstrini
• Keywords (english): olive pomace; β-caroten-linoleate; antioxidant activity; cyclodextrins
• Language: croatian
• URN:NBN: urn:nbn:hr:163:353485
• Study programme: Title: Pharmacy; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra farmacije (magistar/magistra farmacije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-12-13 10:54:45