1. Vsebnost kofeina v kavnih zrnih in kavnih napitkih : diplomsko deloNika Zajšek, 2025, undergraduate thesis Abstract: Kofein je naravni alkaloid iz skupine metilksantinov in sodi med najpogosteje zaužite psihoaktivne spojine na svetu. V diplomskem delu je določena vsebnost kofeina v 30 vzorcih kave, od tega je 28 vzorcev sorte Coffea arabica, en vzorec Coffea canephora (robusta) in en vzorec mešanice obeh vrst. Ekstrakcija kofeina iz zmletih vzorcev je izvedena z dodatkom 40 ml vode na 45 mg mlete kave in z vrenjem 30 min. Iz mlete kave sta pripravljena napitka espreso in turška kava. Koncentracija kofeina je določena s tekočinsko kromatografijo (LC). Rezultati pokažejo, da espreso vsebuje več kofeina na napitek (56,7 ± 1,2 mg/napitek) kot turška kava (40,5 ± 0,8 mg/napitek), medtem ko je izkoristek ekstrakcije višji pri turški kavi (75,7 ± 0,7 %) kot pri espresu (60,3 ± 1,0 %). Svetlo praženi vzorci vsebujejo več kofeina (14,4 ± 0,4 mg/g) kot srednje praženi (12,2 ± 0,4 mg/g). Vpliv metode predelave ni enoznačen, saj sta koncentraciji suhe in mokre metode različni glede na način priprave napitka. Interakcija med metodo predelave in stopnjo praženja ni statistično značilna, pri turški kavi pa se pokaže kot mejno značilna (p = 0,080). Za potrditev interakcije bi bilo potrebno dodatno preverjanje z večjim številom vzorcev.
Keywords: kava (Coffea spp.), kofein, kavni napitki, ekstrakcija kofeina, HPLC
Published in DKUM: 14.10.2025; Views: 0; Downloads: 5
 Full text (1,54 MB) |
2. An overview of the nutritional requirements of honey bees (Apis mellifera Linnaeus, 1758)Leticia Salvioni Ansaloni, Janja Kristl, Caio Eduardo da Costa Domingues, Aleš Gregorc, 2025, review article Abstract: Honey bees are known for their wide global distribution, their ease of handling, and their economic and ecological value. However, they are often exposed to a wide variety of stress factors. Therefore, it is essential for beekeepers to maintain healthy bee colonies. In this context, a balanced diet is recommended to support the growth of strong and healthy honey bee colonies. The purpose of this review is therefore to provide an overview of the nutritional requirements of Apis mellifera and their importance for the maintenance of healthy bee colonies. An adequate diet includes the consumption of sufficient amounts of proteins, carbohydrates, lipids, amino acids, vitamins, minerals, water, and essential sterols, and a diet based on multi-floral pollen is desirable. However, when honey bee colonies are located near agroecosystems with lower resource diversity, both brood rearing and colony longevity may decrease, making them more susceptible to parasites and diseases. On the other hand, efforts have been made to improve the health of honey bee colonies with the help of nutritional supplements consisting of a variety of components. Nevertheless, studies have shown that even with these supplements, a lack of nutrients can still be an issue for honey bee colonies. Furthermore, future research should focus on identifying nutritional supplements that can better replicate natural diet diversity and assessing long-term effects on honey bee colony resilience, especially in low-flowering areas. This review discusses the interaction between nutrient requirements and the effects of supplements on colony health.
Keywords: development, health, nectar, nutrition, pollen
Published in DKUM: 08.08.2025; Views: 0; Downloads: 0
Full text (286,61 KB)
This document has many files! More... |
3. Vpliv pridelovalnega sistema na vsebnost in sestavo organske snovi v tleh : magistrsko deloKaja Mateja Hafner, 2025, master's thesis Abstract: Talno organsko snov (TOS) sestavljajo živi organizmi, odmrli rastlinski in živalski ostanki na različnih stopnjah razkroja ter humus. TOS izboljšuje rodovitnost tal v smislu hranilne vrednosti in vodno-zračnega režima. Namen raziskave je preučiti vpliv konvencionalnega (KON), integriranega (INT), ekološkega (EKO) in biodinamičnega (BD) pridelovalnega sistema na vsebnost organskega ogljika (OC), humina (HN) in črnega ogljika (BC) v tleh. Vzorce tal (0–20 cm) smo odvzeli v letu 2021 s poskusnega polja UKC Pohorski dvor. Vsebnost OC, HN in BC smo določili po oksidaciji organske snovi s K2Cr2O7 v kislem mediju. Povprečna vsebnost OC je bila v EKO (16,2 g/kg) statistično značilno višja v primerjavi s KON (15,3 g/kg) in kontrolo (15,3 g/kg). V vsebnosti HN med pridelovalnimi sistemi ni bilo značilnih razlik, kar je verjetno posledica velike variabilnosti znotraj KON in INT. Povprečna vsebnost HN je bila najnižja v INT (9,5 g/kg) in najvišja v EKO (11,6 g/kg). Povprečna vsebnost BC je bila statistično značilno višja v kontroli (3,3 g/kg) v primerjavi s KON (2,8 g/kg), INT (2,8 g/kg), EKO (2,9 g/kg) in BD (3,0 g/kg). Rezultati kažejo, da dolgoročna trajnostna raba obdelovalnih površin poveča vsebnost OC in HN v tleh, kar prispeva k boljši kakovosti tal in dolgoročni rodovitnosti.
Keywords: organski ogljik, humin, črni ogljik, pridelovalni sistemi
Published in DKUM: 03.06.2025; Views: 0; Downloads: 26
Full text (1,43 MB) |
4. Kemijska sestava in morfološki deskriptorji plodov akcesij Prunus domestica L. in P. cerasifera Ehrh. : magistrsko deloKatja Horvat, 2025, master's thesis Abstract: Magistrska naloga obravnava kemijsko sestavo in morfološke deskriptorje plodov akcesij dveh vrst sliv: Prunus domestica L. in P. cerasifera Ehrh. Namen raziskave je bil ugotoviti razlike v kemijskih in morfoloških lastnostih plodov med tema dvema vrstama ter oceniti njihov potencial kot vir antioksidantov in sladkorjev. V raziskavo smo vključili 31 akcesij sliv, ki smo jih analizirali glede na 18 morfoloških deskriptorjev ter vsebnost sladkorjev, skupnih fenolov in antocianinov. Statistično značilne razlike smo ugotovili pri naslednjih morfoloških lastnostih: velikost plodov, lateralna oblika plodu, simetrija plodu v vertikalnem pogledu, globina šiva sadja pri peclju, barva mesa, trdnost mesa, sočnost ploda ter stopnja spojenosti koščice in mezokarpa. Na drugi strani statistično značilne razlike niso bile ugotovljene pri depresiji na vrhu ploda, prisotnosti dlakavosti, globini votline peclja ploda, osnovni barvi kože, obliki koščice v lateralnem in ventralnem pogledu, površini endokarpa, širini dna koščice ter obliki vrha koščice. Rezultati so pokazali, da se akcesije razlikujejo po barvi eksokarpa. Najpogostejša barva plodov je bila rdeča, ki je predstavljala 36 % vseh plodov, sledi rumena z 21 % in škrlatno vijolična z 12 %. Analiza je pokazala, da je barva plodov v pozitivni korelaciji z vsebnostjo antocianinov. Plodovi z rdečo barvo kože so imeli visoke vrednosti antocianinov (mediana 180,50 mg/100g) in nizke vrednosti sladkorjev (mediana 14,70 °Brix). Plodovi z zeleno barvo eksokarpa so imeli visoke vrednosti sladkorjev (mediana 19,40 °Brix) in nizke vrednosti antocianinov (mediana 7,60 mg/100g). Spearmanov korelacijski test je pokazal, da obstaja močna pozitivna korelacija med vsebnostjo skupnih antocianinov in fenolov.
Keywords: fenoli, antocianini, mirabolana, sliva, ringlo
Published in DKUM: 06.05.2025; Views: 0; Downloads: 16
Full text (2,96 MB) |
5. Dynamics of cyanogenic glycosides in apple and plum fruits, products, and byproducts : a concise reviewJanja Kristl, Lucija Praprotnik, Vilma Sem, 2024, review article Abstract: Apples (Malus domestica) and plums (Prunus domestica) are important fruit crops belonging to the Rosaceae family. The edible parts of fruits and seeds contain phytochemicals; however, the seeds are rich in cyanogenic glycosides (CNGs), which release toxic hydrogen cyanide (HCN) upon the loss of plant cell integrity. This review aims to explore the quantitative and qualitative CNG profiles in apples and plums, focusing on their distribution in different parts of the fruit, changes during fruit development, and environmental impacts on their biosynthesis. It also discusses the intricate dynamics of CNGs in processed fruits and waste-derived products and the effects of the processing methods on CNG content. There is considerable variation in the CNG content of fruit crops, as well as in its distribution in fruit parts other than seeds and shifts during fruit maturation. Although several studies have attempted to explain this variability by the influence of cultivars and exogenous factors, there is insufficient evidence to draw reliable conclusions. Furthermore, due to the lack of studies, the dynamics of CNGs during the storage of fresh or preserved fruit remains unaddressed. In the context of reusing plum stones from waste to produce distillates, it is recommended to monitor the HCN content in the products during storage, as it can increase significantly over time. Processing methods influence CNG levels, with strategies like seed separation, soaking, and microwave heating showing promise in reducing cyanide (CN−) presence. The insights from this review will provide direction for future detailed research.
Keywords: apple, byproducts, cyanogenic glycosides, HCN, plum
Published in DKUM: 17.04.2025; Views: 0; Downloads: 6
 Link to file |
6. |
7. Ozaveščenost potrošnikov in njihov odnos do ostankov pesticidov v hrani : magistrsko deloBarbara Topolovec, 2024, master's thesis Abstract: Uporaba pesticidov in njihovi ostanki v hrani so predmet številnih diskusij v Sloveniji in tujini. Za ublažitev pomislekov glede varnosti hrane je potrebno boljše razumevanje tveganj s strani javnosti, kar lahko dosežemo s spodbujanjem učinkovite komunikacije na področju javnega zdravja. Na drugi strani je pomembno vzpodbuditi pridelovalce hrane k uporabi bolj trajnostnih pristopov pridelave hrane. V ta namen je bila v Podravski regiji marca 2021 na priložnostnem vzorcu (n = 400) izvedena anketna raziskava, s katero se je proučevalo ozaveščenost potrošnikov in njihovo zaskrbljenost o ostankih pesticidov v hrani. Po njihovem mnenju kemikalije, predvsem pesticidi in toksini, najbolj ogrožajo varnost hrane. Vedeli so, da najdemo največ ostankov pesticidov v sadju in zelenjavi, ter po njihovem mnenju v hrani ne smejo biti prisotni. Večina potrošnikov je izrazila skrb in dejala, da se izogibajo hrani, ki vsebuje ostanke pesticidov. Zaskrbljenost glede ostankov pesticidov v hrani je bila statistično značilno višja pri ženskah kot pri moških. Poleg tega menijo, da je tveganje večje od prednosti njihove uporabe in da raje kupijo ekološko pridelane izdelke. Približno polovica jih je izrazila, da pogosto iščejo informacije, kar pomeni, da je varnost hrane pomembna skrb slovenskih potrošnikov. Treba bi bilo nadalje raziskati, kje so ovire, da potrošniki ne posegajo v večji meri po hrani, pridelani s čim manj intervencijami, in kako zmanjšati zaskrbljenost potrošnikov.
Keywords: ostanki pesticidov, splošna javnost, obnašanje potrošnikov, zaskrbljenost glede varnosti hrane, dojemanje tveganja
Published in DKUM: 02.09.2024; Views: 78; Downloads: 61
Full text (1,29 MB) |
8. The distribution of minerals in crucial plant parts of various elderberry (Sambucus spp.) interspecific hybridsNataša Imenšek, Vilma Sem, Mitja Kolar, Anton Ivančič, Janja Kristl, 2021, original scientific article Abstract: In view of growing requirements of the food industry regarding elderberries (genusSambucus), a need to increase their productivity and improve their chemical composition has emerged.With this purpose in mind, numerous elderberry interspecific hybrids have been created. In thepresent work, the content of minerals in their crucial plant parts was studied. It was also investigatedwhether superior genotypes regarding the mineral composition of berries and inflorescences could bepredicted at early stages of plant development. The results showed that elderberry leaves containedthe highest amounts of Ca, Mg, Mn, Zn, and Sr, while K and P were predominant in fruit stalks.Fe and Al prevailed in roots and Cu in bark. Although berries showed lower mineral contentcompared to other plant parts, their mineral content is not negligible and could be comparable toother commonly consumed berries. Genotypes with a favorable mineral content of inflorescencesand berries could be predicted on the basis of known mineral composition of their shoots and leaves.The study also indicates thatS. nigragenotypes and the majority of interspecific hybrids analyzedare suitable for further genetic breeding or cultivation.
Keywords: interspecific hybrids, minerals, plant parts, elderberry, Sambucus
Published in DKUM: 20.08.2024; Views: 70; Downloads: 13
Link to full text
This document has many files! More... |
9. Antioxidant activity of elderberry fruits during maturationNataša Imenšek, Janja Kristl, Tadeja Kraner Šumenjak, Anton Ivančič, 2021, original scientific article Abstract: Antioxidant activity (AOA) in fruits of Sambucus nigra and several new elderberry interspecific hybrids involving S. javanica (JA), S. nigra subsp. nigra (NI), S. nigra subsp. nigra ‘Black Beauty’ (BB), S. nigra subsp. cerulea (CER) and S. racemosa (S. racemosa subsp. racemosa (RAC), S. racemosa subsp. racemosa var. miquelii (MIQ), S. racemosa subsp. tigranii (TIG), S. racemosa subsp. kamtschatica—coreana (KOR) at five maturity stages were investigated by applying DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (ferric reducing antioxidant power) and ORAC (oxygen radical absorption capacity) assays. The aim of the study was to compare different assays for estimating AOA in elderberries, to plan the appropriate harvest time and to determine whether the most promising genotypes could be predicted in advance. All assays used showed that AOA increased significantly during maturation. All assays were significantly correlated with each other and could be reliably used for the AOA determination of elderberries. In fully mature berries, significant correlations were also found between total phenolic (TP) content and AOA by all assays, but no significant correlations were found between total ascorbic acid (TAA) content and AOA by all assays. At the fully mature stage, (the most appropriate stage for harvesting), berries of (JA × NI) × BB and (JA × NI) × MIQ were found to be superior in AOA and TP content. Genotypes with higher/lower AOA and TP content could not be predicted in advance, while TAA showed the opposite.
Keywords: Sambucus, interspecific hybrids, maturation, ABTS, DPPH, ORAC, FRAP, total phenolic content, ascorbic acid, correlations
Published in DKUM: 20.08.2024; Views: 80; Downloads: 11
Full text (747,26 KB)
This document has many files! More... |
10. Vpliv elektrolizirane oksidativne vode na sprejem mineralnih hranil pri visečih in pokončnih pelargonijah : magistrsko deloAnja Vozel, 2024, master's thesis Abstract: Pelargonije (Pelargonium) so bogato cvetoče, živobarvne rastline, ki ob primerni negi cvetijo neprekinjeno od maja do prvih jesenskih zmrzali. Ena izmed alternativ za namakanje rastlin je uporaba elektrolizirane oksidativne vode (EOW). Namen raziskave je bil preučiti vpliv EOW in termina vzorčenja na vsebnost makro‒hranilnih (K, Ca in Mg) in mikro‒hranilnih elementov (Zn, Cu, Fe in Mn) v listih dveh sort pelargonij. V ta namen smo rastline zalivali z vodo (kontrola), 0,1 % in 0,2 % raztopino EOW in vzorčili 63 dni od sajenja potaknjencev ter po 5 tednih rasti. Minerale smo v raztopinah po kislinskem razklopu vzorcev določili z atomsko absorpcijsko in emisijsko spektrometrijo. Zalivanje z 0,1 % in 0,2 % EOW je pozitivno vplivalo na privzem K in Ca pri obeh sortah pelargonij. V drugem terminu vzorčenja smo pozitiven vpliv 0,2 % EOW zaznali tudi pri privzemu Cu pri obeh sortah in Zn pri pokončnih pelargonijah, medtem ko na privzem Mn EOW ni imela vpliva pri nobeni sorti pelargonij. Negativen vpliv obeh koncentracij EOW se je pokazal pri privzemu Fe pri obeh sortah pelargonij v drugem terminu vzorčenja in Mg v prvem terminu vzorčenja. EOW bi lahko bila dobra alternativa za zalivanje potaknjencev pelargonij, ki jih vzgajamo z namenom prodaje sadik na tržišču.
Keywords: pelargonije, hranila, elektrolizirana voda, substrat, korelacija
Published in DKUM: 30.01.2024; Views: 398; Downloads: 94
Full text (1,19 MB) |
