Polyphenol potential of oil cakes

U okviru disertacije ispitana je mogućnost eksploatacije nusproizvoda (nastalih tokom procesa hladnog presovanja ulja) kao izvora prirodnih fenolnih kiselina. Odabir je obuhvatio uzorke uljane tikve, crnog kima, lana i nara. Radi oslobađanja vezanih fenolnih kiselina i u cilju procene njihovog ukupnog sadržaja i distribucije (u čvrstim uzorcima), primenjena je alkalna hidroliza sa dodatkom L-askorbinske kiseline i EDTA. Dobijeni rezultati pokazuju da se sve analizirane pogače mogu se koristiti za dobijanje vrednih fenolnih kiselina, pri čemu raspodela fenolnih kiselina zavisi od vrste uljane pogače. Koncentracija slobodnih fenolnih kiselina se pokazala značajnom za pogaču uljane tikve, estarski vezanih za pogače nara i lana, a nerastvornih-vezanih za pogače crnog kima i nara. Od svih analiziranih uzoraka kora nara je sadržala najviše estarski vezanih fenolnih kiselina zahvaljujući veoma visokom sadržaju galne kiseline. Nakon određivanja fenolnih kiselina u nusproizvodima, analiza glavnih komponenti (PCA) je omogućila razdvajanje biljnih uzoraka u grupe prema poreklu i smanjila broj fenolnih kiselina neophodnih za njihovu karakterizaciju, što može imati potencijalnu primenu u skriningu fenolnih kiselina i određivanju kvaliteta/autentičnosti uljarica i njihovih nusproizvoda.Within the thesis, the possibility of by-products (formed during the process of cold oil pressing) exploitation as a source of natural phenolic acids was examined. Selection of the samples included pumpkin, black cumin, flax and pomegranate. For the purpose of bonded phenolic acids release and for the total phenolic acids content and distribution (in the solid samples) assessment, the alkaline hydrolysis with the addition of L-ascorbic acid and EDTA was employed. The results show that all analyzed cakes can be used to obtain valuable phenolic acids, while the distribution of phenolic acids depends on the type of oil cakes. The concentration of free phenolic acids proved to be significant for a pumpkin oil cake, ester for pomegranate and flax oil cakes, and insoluble-bound for black cumin and pomegranate oil cakes. Of all analyzed samples, pomegranate hull contains the highest content of ester-linked phenolic acids, due to a very high content of gallic acid. After phenolic acids determination in the by-products, principal components analysis (PCA) allowed the separation of plant samples in groups according to origin and reduced the number of phenolic acids necessary for their characterization, which may have potential application in the screening of phenolic acids and determining the quality/authenticity oilseeds and their by-products