20.500.12556/DKUM-97247 Uporaba podkritične vode za ekstrakcijo bioaktivnih spojin iz plodov hrasta (Quercus spp.) magistrsko delo Use of subcritical water for the extraction of bioactive compounds from oak nuts (Quercus spp.) Bioaktivne spojine naravnega izvora so v zadnjih letih v središču raziskovalnega zanimanja zaradi njihovega potenciala za uporabo v živilski, farmacevtski in drugih industrijah. Želodi predstavljajo hranilno bogat, a v sodobni rabi še vedno premalo izkoriščen naravni vir bioaktivnih komponent. V raziskavi smo preučevali uporabo podkritične vode za ekstrakcijo bioaktivnih spojin iz plodov hrasta (Quercus spp.) ter vpliv procesnih parametrov na izkoristek ekstrakcije in sestavo vodotopnih ekstraktov. Ekstrakcije s podkritično vodo smo izvajali pri temperaturah 150 °C, 180 °C in 200 °C, časih 15, 30 in 60 min ter pri razmerjih želod:voda 1:10 in 1:5 (g/mL). V vodotopnih ekstraktih smo določili vsebnost fenolnih spojin, ogljikovih hidratov in antioksidativno aktivnost, posamezne spojine pa smo identificirali s HPLC analizo. Poleg tega smo z GC analizo po Soxhletovi ekstrakciji s petroletrom določili sestavo prostih maščobnih kislin. Trdne ostanke po ekstrakciji smo analizirali s FTIR spektroskopijo. Rezultati so pokazali, da je imela temperatura ključen vpliv na izkoristek in sestavo ekstraktov. Največji izkoristek ekstrakcije (52,5 %) smo dosegli pri razmerju 1:10, temperaturi 180 °C in času 60 min. Najvišji delež totalnih fenolov (127,1 mg GA/g materiala) smo izolirali pri 180 °C, 15 min in razmerju 1:10, najvišji delež taninov (112,9 mg TA/g materiala) pri 150 °C, 60 min in razmerju 1:10, najvišji delež flavonoidov (13,9 mg QU/g materiala) pa pri isti temperaturi in razmerju, vendar času 15 min. Količina izoliranih totalnih ogljikovih hidratov je bila najvišja pri 150 °C, 30 min, razmerju 1:10 (238,9 mg TOH/g materiala), pri čemer je HPLC analiza pokazala intenzivno nastajanje furfurala, 5-MF in 5-HMF z naraščajočo temperaturo in podaljševanjem časa ekstrakcije. Identificirali smo tudi visoke koncentracije galne (28,574 mg/g materiala) in elagne kisline (17,074 mg/g materiala), EGKG (2,141 mg/g materiala), katehina (0,327 mg/g materiala) in izokvercetina (0,881 mg/g materiala). Antioksidativno aktivnost ekstraktov smo določili z DPPH metodo, večina ekstraktov pa je pokazala izjemno antioksidativno aktivnost (nad 90 %). Analiza oljne frakcije je pokazala vsebnost 36 % prostih maščobnih kislin, pri čemer so bile linolna, oleinska in palmitinska kislina zaznane v največjih koncentracijah. Na podlagi rezultatov smo ugotovili, da je ekstrakcija s podkritično vodo učinkovita in okolju prijazna metoda za pridobivanje bioaktivnih spojin iz želodov ter predstavlja obetaven pristop za njihovo nadaljnjo trajnostno uporabo. Bioactive compounds of natural origin have attracted increasing research interest in recent years due to their potential applications in the food, pharmaceutical, and other industries. Acorns represent a nutritionally rich but still underutilized natural source of bioactive components. In this study, the use of subcritical water for the extraction of bioactive compounds from oak acorns (Quercus spp.) was investigated, with particular emphasis on the influence of process parameters on extraction yield and the composition of water-soluble extracts. Subcritical water extractions were performed at temperatures of 150 °C, 180 °C, and 200 °C, extraction times of 15, 30, and 60 min, and acorn-to-water ratios of 1:10 and 1:5 (g/mL). In the water-soluble extracts, the contents of phenolic compounds and carbohydrates, as well as antioxidant activity, were determined, while individual compounds were identified by HPLC analysis. In addition, the composition of free fatty acids was determined by GC analysis following Soxhlet extraction. Solid residues after extraction were analyzed using FTIR spectroscopy. The results showed that temperature significantly influenced extraction yield and extract composition. The highest extraction yield (52.5 %) was obtained at an acorn-to-water ratio of 1:10, a temperature of 180 °C, and an extraction time of 60 min. The highest total phenolic content (127.1 mg GA/g material) was achieved at 180 °C, 15 min, and a 1:10 ratio. The highest tannin content (112.9 mg TA/g material) was observed at 150 °C, 60 min, and a 1:10 ratio, while the highest flavonoid content (13.9 mg QU/g material) was obtained at the same temperature and ratio, but with an extraction time of 15 min. The total carbohydrate content was highest at 150 °C, 30 min, and a 1:10 ratio (238.9 mg TOH/g material). HPLC analysis revealed increased formation of furfural, 5-MF, and 5-HMF with increasing temperature and prolonged extraction time. High concentrations of gallic acid (28.574 mg/g material), ellagic acid (17.074 mg/g material), EGKG (2.141 mg/g material), catechin (0.327 mg/g material), and isoquercetin (0.881 mg/g material) were identified. Antioxidant activity, evaluated using the DPPH method, showed that most extracts exhibited exceptionally high antioxidant activity (above 90 % inhibition). Analysis of the oil fraction showed a free fatty acid content of 36 %, with linoleic, oleic, and palmitic acids present at the highest concentrations. Based on these results, subcritical water extraction was demonstrated to be an efficient and environmentally friendly method for the recovery of bioactive compounds from acorns, representing a promising approach for their further sustainable utilization. želod podkritična voda biomasa fenolne spojine maščobne kisline acorn subcritical water biomass phenolic compounds fatty acids true true false [N. Menciger Kocbek] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-02-24 19:54:27 2026-05-04 09:09:42 2026-05-07 03:10:23 0000-00-00 00:00:00 2026 0 Maribor 0 Maribor 1 spletni vir (1 datoteka PDF (XI, 58 str.)) 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 [66.061.3:54-139]:547.9(043.2) 277132803 MAG_Menciger_Kocbek_Neja_2026.pdf MAG_Menciger_Kocbek_Neja_2026.pdf 1 3357279DB0A4E5045E22BE3228D95BEB c26de090f3c005fc61542a4d0c7c5b1d77df6bcb88660f42d6f03f56f0aebed4 d95f38ee-4304-11f1-b28d-00155d0001a1 https://dk.um.si/Dokument.php?lang=slv&id=205671 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0