Sestava olj iz semen različnih sort vinske trte, pridobljenih z ekstrakcijo s heksanom, superkritičnim ogljikovim dioksidom in stiskanjem

Kunst, Neja (author), Kočevar Glavač, Nina (mentor), Ravnikar, Matjaž (co-mentor)

Pridelava grozdja je ena najbolj razširjenih kmetijskih dejavnosti, vendar ustvarja tudi veliko odpadkov. Med temi so aktualna grozdna semena, ki jih uporabljamo za pridobivanje olja. Med najbolj poznane metode ekstrahiranja olja spadajo: ekstrakcija z organskim topilom (heksanom), hladno stiskanje in ekstrakcija s superkritičnim ogljikovim dioksidom (CO2). Te metode smo uporabili tudi mi in ekstrahirali semena iz šestih različnih sort grozdja: pinela, sauvignon, beli pinot, laški rizling, cabernet sauvignon in refošk. Ugotovili smo, da je bil največji izplen pri CO2 ekstrakciji, sledila je ekstrakcija s heksanom in nato hladno stiskanje. Maščobnokislinsko sestavo pridobljenih olj grozdnih semen smo preverili s plinsko kromatografijo, sklopljeno z masno spektrometrijo (GC-MS). V največjem deležu je bila zastopana linolna kislina, ne glede na uporabljeno tehniko ekstrakcije, nato oleinska, stearinska in palmitinska. Vsebnost miristinske kisline je najbolj nihala glede na sorto grozdja. Ugotovili smo, da metoda ekstrakcije ni imela bistvenega vpliva na maščobnokislinsko sestavo. Kakovost olja določajo tudi neumiljive snovi, zato smo v raziskavi ugotavljali tudi vsebnost tokoferolov in fenolnih spojin v oljih grozdnih semen. Vsebnost tokoferolov smo ugotavljali s tekočinsko kromatografijo visoke ločljivosti (HPLC). δ-tokoferolov ni bilo zaznati v nobenem vzorcu. Najvišja vsebnost α- in β-tokoferolov je bila v vzorcih ekstrakcije s heksanom. Vsebnost fenolnih spojin smo ugotavljali s Folin-Ciocalteujevo metodo. Iz rezultatov sklepamo, da s heksansko ekstrakcijo pridobimo več fenolnih spojin kot s hladnim stiskanjem. Ekvivalent galne kisline v olju smo določali z metodo DPPH, saj je olje poznano po svojem antioksidativnem delovanju. Vzorce smo raztapljali v DMSO in etanolu. Pri vzorcih, redčenih z DMSO, smo ugotovili, da metoda ekstrakcije ni vplivala na antioksidativno aktivnost. Pri vzorcih, redčenih z etanolom, pa so rezultati pokazali najvišjo antioksidativno aktivnost v heksanskih vzorcih.

• Language: Slovenian
• Keywords: antioksidanti, CO2 ekstrakcija, ekstrakcija s topili, hladno stiskanje, olje grozdnih semen
• Work type: Bachelor thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2024
• PID: 20.500.12556/RUL-154147
• Publication date in RUL: 27.01.2024

Secondary language

• Language: English
• Title: Composition of seed oil of different grape varieties obtained by extraction with hexane, supercritical carbon dioxide and pressing

Abstract

Grape production is one of the most widespread agricultural activities, but it also generates a lot of waste. Grape seeds, which are used for oil extraction, are one of the most important of these wastes. The most well-known methods of extracting the oil are: extraction with an organic solvent (hexane), cold pressing and extraction with supercritical carbon dioxide (CO2). We used these methods to extract the seeds from six different grape varieties: pinela, sauvignon, pinot blanc, riesling, cabernet sauvignon, refosco. We found out that CO2 extraction yielded the highest yields, followed by hexane extraction and cold pressing. The fatty acid composition of the extracted grape seed oils was analysed by gas chromatography coupled with mass spectrometry (GC-MS). Linoleic acid was represented in the largest proportion, regardless of the extraction technique used, followed by oleic, stearic and palmitic acids. Myristic acid content varied the most depending on the grape variety. We found out that the extraction method had no significant effect on the fatty acid composition. The quality of the oil is also determined by the unsaponifiable substances, and in this research the content of tocopherols and phenolic compounds in grape seed oils was also determined. The tocopherol content was determined by high-performance liquid chromatography (HPLC). δ-Tocopherols were not detected in any of the samples. The highest α- and β-tocopherol content was found in the hexane extraction samples. The content of phenolic compounds was determined by the Folin-Ciocalteu method. From the results we conclude that hexane extraction yields more phenolic compounds than cold pressing. The equivalent of the gallic acid in the oil was determined by the DPPH method, as the oil is known for its antioxidant activity. Samples were prepared with DMSO and ethanol. For the samples diluted with DMSO, the results showed that the extraction method did not affect the antioxidant activity. However, for the samples diluted with ethanol, the highest antioxidant activity was found in the hexane samples.

• Keywords: antioxidants, cold pressing, CO2 extraction, grape seed oil, solvent extraction