| Sažetak | Kava predstavlja jedan od najpopularnijih i najčešće konzumiranih napitaka na svijetu s čime nastaje i velika količina otpada čije zbrinjavanje predstavlja značajan ekološki problem. U ovom radu provedena je analiza ulja iz otpadnog taloga kave iz ugostiteljskih objekata kako bi se istražila mogućnost njegove primjene u proizvodnji biodizela. Iz prikupljenog taloga provedena je ekstrakcija kako bi se dobilo ulje taloga kave, te su određena fizikalno-kemijska svojstva. U dvama uzorcima određeni su udjeli vode (34,63 ± 1,51 % i 50,84 ± 0,58 %) i ulja (13,44 % ± 0,40 % i 23,7 % ± 0,20 %). Peroksidni broj za uzorke ulja iznosio je 0,92 mEq mEq O₂/kg ± 0,02 i 0,90 mEq O₂/kg ± 0,09. Određeni su i kiselinski broj (6,13 ± 0,03 i 5,64 ± 0,02 mg KOH/g), kao i sastav masnih kiselina, njihovo pozicioniranje, među kojima je ukupno dominantna linolna masna kiselina (39,26 % i 40,05 %), a slijede ju palmitinska (34,49 % i 32,87 %) i stearinska (11,58 % i 12,42 %). Određena je i distribucija masnih kiselina na sn-2 poziciji, gdje se ponovo ističe linolna masna kiselina (60,33% i 61,41%), zatim palmitinska (15,32% i 14,65%) i oleinska (13,68% i 13,64%). Oksidacijska stabilnost ulja provedena je diferencijalnom motridbenom kalorimetrijom pod tlakom (PDSC). |
| Sažetak (engleski) | Coffee is one of the most popular and frequently consumed beverages in the world, which results in a large amount of waste, the disposal of which poses a significant environmental challenge. This study analyzes the oil from spent coffee grounds to explore its potential use in biodiesel production. The oil was extracted from the collected grounds, and its physicochemical properties were determined. The water content in two samples was found to be 34.63 ± 1.51 % and 50.84 ± 0.58 %, while the oil content was 13.44 ± 0.40 % and 23.7 ± 0.20 %. The peroxide value for the oil samples was 0.92 mEq O₂/kg ± 0.02 and 0.90 mEq O₂/kg ± 0.09. The acid number was also determined (6.13 ± 0.03 and 5.64 ± 0.02 mg KOH/g), as well as the fatty acid composition and their positioning, with linoleic acid being the dominant fatty acid (39.26 % and 40.05 %), followed by oleic acid (34.49 % and 32.87 %) and stearic acid (11.58 % and 12.42 %). The distribution of fatty acids at the sn-2 position was also determined, where linoleic fatty acid (60.33% and 61.41%), followed by palmitic acid (15.32% and 14.65%) and oleic acid (13.68% and 13.64%). The oxidation stability of the oil was assessed using pressure differential scanning calorimetry. |
