Vpliv pospešenega staranja na kristalizacijo in oksidativno stabilnost ričkovega in konopljinega olja

Kragelnik, Jasmina (author), Prislan, Iztok (mentor)

V diplomski nalogi smo preverjali vpliv pospešenega staranja na kristalizacijo in oksidativno stabilnost ričkovega in konopljinega olja. Za izvedbo eksperimentov smo uporabili metodi rancimat in diferenčno dinamično kalorimetrijo (DSC). Vzorcem olj, ki smo jih z metodo rancimat pospešeno starali pri 120 ␃ in prepihovali z zrakom pretoka 15 L/min, smo izmerili čase, pri katerih se začnejo tvoriti sekundarni produkti oksidacije (indukcijske čase). Rezultati metode rancimat so bili za obe vrsti olj pod uporabljenimi eksperimentalnimi pogoji podobni in v povprečju znašali 2,1 h. Velik delež obeh olj namreč sestavljajo večkrat nenasičene maščobne kisline (VNMK), zaradi česar sta olji oksidativno manj stabilni. Eksperiment bi morali izvesti še pri nižjih delovnih temperaturah, da bi ugotovili morebitne razlike med preučevanimi olji. Z DSC smo analizirali sveže vzorce olj in jih primerjali z vzorci, ki smo jih predhodno pospešeno starali z rancimatom. Termogrami svežih olj so se razlikovali od termogramov olj, ki so bili pospešeno starani dve uri, kar lahko pripišemo vplivu oksidacije in posledično spremenjeni maščobno-kislinski sestavi. Med termogrami svežih vzorcev in vzorcev, ki so bili pospešeno starani eno uro pa smo opazili malo razlik. Rezultati metode rancimat se ujemajo z rezultati metode DSC, saj termogrami svežih vzorcev in dve uri pospešeno staranih vzorcev prikazujejo popolnoma drugačne fazne prehode.

• Language: Slovenian
• Keywords: ričkovo olje, konopljino olje, oksidativna stabilnost, kristalizacija, fazni prehodi, rancimat, diferenčna dinamična kalorimetrija, indukcijski čas
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: [J. Kragelnik]
• Year: 2021
• PID: 20.500.12556/RUL-130549
• UDC: 664.34.094.3:665.3
• COBISS.SI-ID: 76344323
• Publication date in RUL: 16.09.2021

Secondary language

• Language: English
• Title: Crystallization profile and oxidative stability of camelina sativa and hemp oil under accelerated aging

Abstract

In this graduation thesis, we examined the influence of accelerated aging on the crystallisation and oxidative stability of camelina sativa oil and hemp oil. To perform the experiments, we used rancimat and differential scanning calorimetry (DSC). With rancimat, we measured induction times at which secondary oxidation products begin to form. Rancimat experiments were performed at 120 ␃ and airflow set at 15 L/min. For both oils, the rancimat result showed an average value of 2.1 h. Results obtained under these experimental conditions did not show significant differences between both oils. Both oils contain high amounts of polyunsaturated fatty acids, which makes them less resistant to oxidation. The experiment should be performed at lower operating temperatures in order to determine possible differences between both oils. By DSC we analysed fresh oil samples and samples previously analysed with rancimat and compared the results. The thermograms of fresh oils were very different from thermograms of oils kept in rancimat for two hours. Differences can be attributed to the fatty acid oxidation. If we compare thermograms of fresh samples with thermograms of samples that were kept in rancimat for one hour, we observe only minor differences. Results obtained from rancimat and DSC revealed that induction time coincides with changes in thermograms.

• Keywords: Camelina sativa oil, hemp oil, oxidative stability, crystallization, phase transitions, rancimat, differential scanning calorimetry, induction time