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2.
VSEBNOST POLIFENOLOV V OLJU GROZDNIH PEŠK
Enej Koron, 2023, undergraduate thesis

Abstract: Diplomska naloga obravnava pridobivanje olje iz grozdnih pešk s hladnim stiskanjem. V nalogi smo izvedli postopek izolacije in priprave pešk na stiskanje na kmetiji (ne v laboratoriju), samo stiskanje olja na hladen način oz. brez dodatnega segrevanja v vijačni stiskalnici, ki je bila razvita za tako zahtevna semena kot so grozdne peške. V nalogi smo primerjali stiskanje pešk in tudi olje pešk štirih belih sort grozdja 'Pinela', 'Beli pinot', 'Laški rizling', 'Sauvignon' in dveh rdečih sort 'Cabernet sauvignon' in 'Refošk'. Sorte so se zelo malo razlikovale v izplenu olja, ki je znašal v povprečju 9 masnih %, kar je bilo nekoliko manjše kot pri drugih objavah v literaturi – kar je mogoče posledica sezone, pa tudi mehanskega stiskanja, za katerega je iz literature znano, da ima najmanjši izplen – v primerjavi z drugimi metodami ekstrakcije olja. Analiza olja je pokazala prisotnost raznolikih fenolnih spojin - različnih nizkomolekularnih tanininov – procianidinov B1, B2, C1, fenolnih kislin kot je galna kislina, protokatehinska kislina, kavna kislina, klorogenska kislina, p-kumarna kislina in flavonolov katehina in epikatehina. Seštevek vseh kromatografsko določenih fenolnih spojin je variral od 3,75 μg/g pri olju Pinela pa do 9,98 μg/g v olju Refošk. Pri skupnih fenolih, določenih po metodi Folin-Ciocalteu pa od 14,08 μg (kot galna kislina)/g (olje Sauvignon) pa do 35,23 μg (kot galna kislina)/g (olje Refošk). V olju različnih sort so vsebnosti skupnih in posameznih fenolov zelo varirale, na splošno pa smo ugotovili, da mehansko pridobljeno olje pešk rdečih sort vsebuje v povprečju vsebuje tudi do dvakrat večje koncentracije skupnih fenolov kot olje belih sort. Ugotovili smo, da v povprečju v procesu mehanskega stiskanja prehaja v olje zgolj 0,02 % vseh prisotnih fenolnih spojin, torej večina ostane v pogači, ki bi jo lahko še nadalje uporabili ne le kot vir beljakovin, ampak tudi kot vir polifenolov.
Keywords: olje, grozdne peške, Vitis vinifera L., fenoli, mehansko stiskanje olja
Published in RUNG: 07.09.2023; Views: 740; Downloads: 13
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3.
Fenolni potencial izbranih vin s podaljšano maceracijo sorte "Rebula"
Dejan Bavčar, Yelyzaveta Popova, 2023, undergraduate thesis

Abstract: V diplomski nalogi smo analizirali 30 vzorcev vin sorte grozdja Vitis vinifera L. cv. 'Rebula' iz Vipavske doline in Goriških brd. Vina smo kupili na trgu, in sicer v specializiranih lokalnih prodajalnah vina, spletnih prodajalnah ali pri vinarjih. Osemindvajset (28) vzorcev vina je bilo pridelanih s postopkom podaljšane maceracije drozge grozdja. Dve vini pridelanih brez maceracije, smo dodali v nabor vzorcev zaradi primerjave fizikalno-kemijskih parametrov z ostalimi vzorci. V vinskih vzorcih smo izmerili naslednje standardne fizikalno-kemijske parametre: skupni in prosti žveplov dioksid, skupne titrabilne kisline, pH, hlapne kisline z destilacijsko metodo, izbrane organske kisline, sladkorje (glukozo + fruktozo), etanol in barvo vina s spektofotometrom - absorbanco pri 420 nm (A420) in barvne parametre v CIE Lab sistemu. Izmerili smo tudi skupne polifenole po spektrofotometrijski metodi Folin-Ciocalteu in izbrane posamezne polifenole (hidroksibenzojske kisline, nezaestrene hidroksicimetne kisline, procianidine) s tekočinsko kromatografijo visoke ločljivosti, sklopljeno z UV detetktorjem (HPLC-UV). Želeli smo določiti polifenolni potencial vin sorte 'Rebula', pridelanih s postopkom podaljšane maceracije drozge grozdja in nato določiti morebiten vpliv časa maceracije na količino polifenolov v vinu. Kemijske analize so pokazale veliko variabilnost v količini skupnih polifenolov, ki pa jih nismo uspeli povezati s časom maceracije. Pomanjkljivi podatki o času in drugih pogojih maceracije drozge grozdja nam tega niso dopuščali. Podatki nakazujejo trend večjih koncentracij skupnih polifenolov vina pri vinih, pridelanih s postopkom podaljšane maceracije drozge grozdja. V določenih vinih smo izmerili tudi preko 1000 mg/L (kot galna kislina) skupnih polifenolov. Med posameznimi polifenoli je bilo v vinih največ galne kisline (tudi do 90 mg/L), procianidina B1 (do 52 mg/L) in katehina (do 18 mg/L). Instrumentalno določena barva filtriranega vina (A420 in parametri CIE Lab) je povezana s količino skupnih polifenolov po metodi Folin-Ciocalteu. Parametri barve dolgo maceriranih vin se močno razlikujejo od vin brez maceracije oziroma od vin, pridelanih s krajšim časom maceracije, zato gre za dobre 'markerje' tovrstnih vin. Opazili smo, da kombinacija običajnega parametra barve belih vin A420 nm s parametri CIE Lab sistema omogoča podrobnejšo analizo barve vina.
Keywords: Vitis vinifera L. cv. ‘Rebula’, belo grozdje, belo vino, postopek maceracije, polifenoli
Published in RUNG: 06.07.2023; Views: 984; Downloads: 16
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4.
Biogenic amines in Hardanger ciders : the effect of native cider yeasts on biogenic amine production
Urban Česnik, Mitja Martelanc, Branka Mozetič Vodopivec, Ingunn Ovsthus, Lorena Butinar, 2023, published scientific conference contribution abstract

Abstract: The presence of bioactive compounds in food and beverages of plant origin is mainly connected with higher nutritional value and better sensory properties. However, some of them can pose a threat to food product quality and human health. For example, excess biogenic amines (BAs) intake can cause different allergenic responses in individuals who have such intolerances. BAs have been intensively studied in recent years, especially in fermented foods like wine, meat, fish, and cheese. Among fermented beverages is apple cider still rather unexplored from this perspective. Especially since no such data exist for the Norwegian cider. Norwegian cider is becoming more and more popular in Norway in recent years among producers and consumers. Hardanger cider from Western Norway is very different from French, English, or Spanish ciders in terms of sensory characteristics, apple cultivars, and in the fermentation process. In Hardanger, the traditional cider is still produced by spontaneous fermentation of apple juice with naturally occurring yeasts that originate from the fruit or processing equipment surfaces. Lactic acid bacteria are known to be associated with BA formation. However, several studies reported about the BA-producing yeasts in winemaking. Due to the important role of natural yeasts in the production of Hardanger cider, we focused on the ability of BA formation by native yeasts. Thus, in our study, we followed the amounts of BAs in the Hardanger ciders during the fermentation process and characterize isolated yeasts if they have the ability to produce BAs under cidermaking conditions by performing a micro-fermentation experiment. From must/cider samples, taken during the fermentation process at 13 producers in the Hardanger region, we isolated 530 yeast isolates. Based on the sequencing of the D1/D2 domain of the 26S rDNA we identified 25 different yeast species. As expected, yeast diversity was higher at the beginning compared to the middle fermentation stage, when mostly different non-Saccharomyces yeast species prevailed, while at the end of fermentation mainly Saccharomyces species with high ethanol tolerance were present. BAs were analyzed with the HPLC-UV method. In all apple juice/cider samples 4 different BAs (putrescine, cadaverine, histamine, and tyramine) were detected and quantified with external calibration. On average in all cider samples from the producers total BA (summation of all BAs) concentration reached 9,45 mg/L, however in one case even 25 mg/L. Tyramine was the most abundant BA in all fermentation stages. 40 isolated yeast strains were further tested for BA formation in a small-scale experiment by fermenting apple juice. Results show that non-Saccharomyces yeasts mainly form histamine (1,68 mg/L) and tyramine (1,30 mg/L), while Saccharomyces yeasts putrescine (0,48 mg/L) and tyramine (3,53 mg/L). As a general conclusion, the occurrence and distribution of BA concentrations in the small-scale fermentation were lower (2,96 mg/L and 4,01 mg/L) and less variable than in the real ciders (average in final ciders 9,45 mg/L) and with tyramine being the most abundant BA in all samples analyzed.
Keywords: cider, yeast, biogenic amines, Hardanger, biodiversity
Published in RUNG: 23.06.2023; Views: 849; Downloads: 5
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Cider yeasts associated with Hardanger cider during fermentation process
Urban Česnik, Mitja Martelanc, Branka Mozetič Vodopivec, Ingunn Ovsthus, Lorena Butinar, 2022, published scientific conference contribution abstract

Abstract: In the Hardanger area in Western Norway, the production of cider has a long tradition that goes back to the 12th century, when monks introduced apple growing in this area. Nowadays, this is also the main area of fruit production in Norway. Despite the strict regulation of the alcoholic beverage production in Norway, traditional cider is still produced on some farms in this area. Therefore, our aim was to study the ecology and biodiversity of the yeasts associated with the cider production in the Hardanger area during fermentation process; especially of traditional cider, which is produced by a spontaneous fermentation of apple juice, performed by naturally occurring indigenous yeasts that originate from the fruit or the surfaces of the processing equipment. In our study, samples of fermenting juice/cider were taken during fermentation process from 12 producers, located in 12 different locations in Hardanger region. Classical cultivation methods using WL (Wallerstein Laboratories) agar medium with added chloramphenicol enable us to isolate a total of 530 yeast isolates that were stored in in-house yeast collection at the NIBIO and included also at the Wine Research Centre collection. Based on the sequencing of the D1/D2 domain of the 26S rDNA we managed to identify 357 isolates and distinguished 27 different yeast species as follows: Aureobasidium pullulans, Candida californica, C. oleophila, C, sake, Hanseniaspora meyeri, H. uvarum, H. valbyensis. Kregervanrija fluxuum, Kregervanrija sp., Metschnikowia andauensis, M. chrysoperlae, M. fructicola, M. pulcherrima, Metschnikowia sp, Pichia fermentans, P. kluyveri, P. membranifaciens, P. nakasei, Piskurozyma capsuligena, Rhodotorula nothofagi, Saccharomyces bayanus, S. cerevisiae, S. paradoxus, S. pastorianus, Saccharomyces sp., S. uvarum and Torulaspora delbrueckii. Even though we were not able to obtain samples in three different fermentation stages (beginning, middle and at the end of fermentation) from all producers, we could observe yeast succession during fermentation progress. Yeast diversity was higher at the beginning comparing to the middle of fermentation, when mostly different non-Saccharomyces yeast species prevailed, while in the middle of fermentation 11 species were detected (Candida californica, H. uvarum, H. valbyensis, Kregervanrija sp., K. fluxuum, Pichia membranifaciens, Metschnikowia pulcherrima, Saccharomyces sp, S. bayanus, S. uvarum and S. cerevisie). On the other hand, at the end of fermentation mainly Saccharomyces species with high ethanol tolerance were present (Saccharomyces sp., S. cerevisiae, bayanus, S. uvarum and P. fermentans). In samples that were collected from three producers in all three fermentation stages also quality parameters were determined (ethanol, organic acids, sugars, biogenic amines) with in-house developed methods using HPLC-UV/RID. The most important sugars in ciders were fructose and glucose, as expected. Two producers added sugar to increase the level of ethanol in the middle of fermentation, which is a common procedure in the Hardanger area. Ethanol and organic acid analysis indicated that fermentations went in the right direction, since all parameters were within normal limits. Including the acetic acid level, an indicator of low cider quality, was very low (average around 0,06 g/L). The alcohol incised from the beginning to end fermentation in all samples analysed and minimum concentration was 2,71 g/L. In ciders we detected four biogenic amines (putrescin, cadaverine, histamine and tyramine). The average amount was 32 mg/L and the most abundant was tyramine.
Keywords: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making
Published in RUNG: 18.10.2022; Views: 1086; Downloads: 0
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7.
Validacija HPLC metode za določanje organskih kislin in sladkorjev v vinu
Kristjan Mesar, 2022, undergraduate thesis

Abstract: V tem diplomskem delu smo obravnavali proces validacije dveh analiznih metod za določanje kakovosti vina. In sicer smo določali organske kisline kot so vinska kislina, jabolčna kislina, mlečna kislina, citronska kislina, ocetna kislina, in monosaharide glukozo in fruktozo. Analiza teh parametrov je pomembna pri nadzoru procesa pridelave vina kot tudi spremljanju kakovosti vina. V diplomski nalogi smo pregledali glavne metode za določanje kislin in sladkorjev v grozdju in vinu, v samem poskusu pa smo uporabili kromatografsko tehniko na osnovi tekočinske kromatografijo visoke ločljivosti v kombinaciji z detekcijo v ultravijoličnem (UV) za organske kisline in z detekcijo lomnega količnika (RID) za monosaharidne sladkorje. HPLC-UV/RID sistem omogoča enostavno pripravo vzorca na analizo (samo filtracija, mogoče redčitev, če je potrebna), hitro analizo in omogoča zadovoljive meje detekcije za potrebe določevanja omenjenih parametrov. Obe metodi smo opisali z različnimi parametri, kot je ponovljivost, linearnost, izkoristek v štirih različnih matriksih (dve beli vini, eno rdeče in eno jabolčno vino – cider), meja detekcije in meja kvantifikacije. Rezultate kvantifikacije skupnih sladkorjev in organskih kislin v vzorcih vin smo primerjali z rezultati akreditiranega laboratorija kjer je bilo to mogoče in ugotovili, da kvantifikacija z metodo standardnega dodatka omogoča primerljive rezultate z akreditiranim laboratorijem, predvsem za parameter skupni fermentirani sladkorji (glukoza in fruktoza). Vsebnost skupnih kislin določenih kromatografsko je bila nekoliko manjša od parametra skupne titrabilne kisline, kar je najverjetneje posledica manjšega števila posameznih kislin, ki smo jih vključili v ta parameter, pa tudi drugačne metode določanja kislin.
Keywords: vino, cider, HPLC, UV, RID, organske kisline, sladkorji, validacija
Published in RUNG: 02.08.2022; Views: 1674; Downloads: 58
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8.
Novel analytical approaches in quality and safety control in production of fermented beverages : dissertation
Jelena Topić, 2022, doctoral dissertation

Abstract: The exploitation of microorganisms for fermentation goes back centuries. Two types of fermentation are usually used in the winemaking process – alcoholic fermentation and malolactic fermentation. Nowadays, inoculated fermentations with the use of starter cultures are commonly used in order to produce wine with more consistent quality. However, wines can lack in flavour complexity, so scientists and the industry are constantly looking for new and improved starters that can be adapted to different types of wine. In this work we focused on the development and implementation of novel analytical methods for wine quality control. In the course of method development native yeasts and lactic acid bacteria isolates were characterized for wine starter properties. We focused on the determination of biologically active compounds that determine wine quality and safety. Yeasts can influence wine colour through their adsorption capacity and synthesis of stable colour pigments pyranoanthocyanins and lactic acid bacteria can produce biogenic amines which can have adverse detrimental health effects on sensitive consumers when they are present in wines.
Keywords: Saccharomyces yeasts, non-Saccharomyces yeasts, pyranoanthocyanins, thermal-lens spectrometry, lactic acid bacteria, biogenic amines, thin layer chromatography, dissertations
Published in RUNG: 18.02.2022; Views: 2483; Downloads: 118
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9.
Determination of biogenic amines formation by autochthonous lactic acid bacteria from ‘Refošk’ grapes using different analytical methods
Jelena Topić, Lorena Butinar, Martina Bergant Marušič, Dorota Korte, Branka Mozetič Vodopivec, 2022, original scientific article

Abstract: Different analytical methods were tested and optimized for the determination of four biogenic amines (BA) histamine, putrescine, cadaverine and tyramine produced by grape-associated lactic acid bacteria (LAB). Autochthonous LAB were isolated from ‘Refošk’ grapes belonging to Slovenian-Italian Karst region as they represent a potential pool of beneficial LAB starter bacteria for improving the typicality and quality of wine. Six isolated strains were screened by multiplex PCR, of which four strains were positive for BA-forming genes (MKBT-49, MKBT-282, MKBT-568, MKBT-570). The production of BA was evaluated by thin-layer chromatography (TLC), high-performance liquid chromatography coupled to diode array detection (HPLC-DAD) and enzymatic method. The HPLC-DAD results showed that strain MKBT-49 (tyrdc+) had high tyramine production (386.6 ± 0.14 mg/L), which was confirmed by TLC. The ability to produce putrescine was confirmed in strain MKBT-282 by PCR, HPLC-DAD (16.4 ± 1.72 mg/L), and TLC. Histamine-producing ability was detected in strain MKBT-570, with a concentration below the limit of detection of the HPLC-DAD (<0.2 mg/L), while the other two methods were not sensitive enough for confirmation. This study shows that the production of BA can detected in native LAB and that relatively simple method such as TLC can be used effectively for the initial screening.
Keywords: grapes, wine-like matrices, biogenic amines, autochthonous lactic acid bacteria, analytical methods
Published in RUNG: 03.01.2022; Views: 1593; Downloads: 7
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