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11.
CHARACTERIZATION OF SLOVENIAN APPLE JUICE WITH RESPECT TO ITS GEOGRAPHICAL ORIGIN AND AGRICULTURAL PRODUCTION PRACTICE
Karmen Bizjak Bat, 2016, doktorska disertacija

Opis: Determination of food authenticity is an important issue in quality control and food safety. Recent studies predict a growing demand for natural and more authentic food and beverage products. The quality and authenticity of apple juice is also of a great economic importance since the popularity and demand for apple juice consumption has increased. The growth of the market for organically produced apples and apple juice is due to the increasing demand for healthy food requirements, protection of the environment and the promotion of biotic diversity. Organic foods have a higher nutritional and health value, but they are more expensive, because their production is more difficult and less profitable. In addition to how food is produced, consumers are increasingly placing emphasis on food products of specific region, which are known for their unique natural flavours and taste. The presented thesis is based on four separate but closely interrelated studies, in which a combination of different isotopic ratios of bioelements (2H/1H, 13C/12C, 15N/14N, 18O/16O), multi-element analysis, and major primary and secondary metabolite profiles were exploited to differentiate the geographical origin and agricultural production practice (organic vs integrated/conventional) of Slovenian apples. These parameters were used to establish the first database of authentic Slovenian apple juice, which can be used to verify the authenticity of commercially available apple juice in Slovenia. The first preliminary study was entitled “Organic Cultivation ~ Geographical Origin (OCGO)” and was performed using apples from the 2009 growing season. Its aim was to examine the use of stable isotope and multi-element data for determining the geographical origin and agricultural production practice of fresh apple juices. Fruits of six apple (Malus domestica Borkh) cultivars (Topaz, Idared, Golden Delicious, Goldrush, Gala, Gloster) were collected from four different geographical regions of Slovenia (Alpine, Dinaric, Pannonian and Mediterranean) grown under organic and integrated/conventional orchard management systems. The results revealed that stable isotope parameters in sugar, pulp and water were the most significant variables for differentiating between the regions. Good separation was achieved between the geographical regions in Slovenia based on the δ18O and δ2H values in water and Rb and S levels in the apple fruit juice. The most significant variables that distinguished between organically and integrated/conventionally cultivated apples were the 15N/14N ratio and antioxidant activity of the apple juice. Significant differences were also observed in the ascorbic acid content of the juice. Based on these results the number and types of apples and the minimum number of samples needed from the same region for determining geographical origin were determined. The second study was called “Organic ~ Conventional Apple Cultivation” (OCAC) and was performed in 2010 and 2011 in a Gala apple orchard. The aim was to determine the effect of different fertilizers allowed either in organic or conventional/integrated agricultural regimes on different parameters. Quality parameters, isotopic composition of C in sugars and in pulp together with N and elemental analysis were investigated. The following five fertilizers were applied: Biosol and Plantella organic (organic) and Ca cyanamide, KAN and UREA (mineral) at a rate of 60 and 120 kg of nitrogen per hectare. From the obtained data it was possible to differentiate between organic and integrated/conventional apple production when taking into account the following parameters: mass, skin and flesh firmness (SFF), total soluble solids (TSS), and the content of Cl as well as δ15N and δ13C in the pulp. The “Organic Cultivation ~ Geographical Origin” (OCGO) study, which took place during the 2011 and 2012 growing seasons included a greater number of samples and samples from five different geographical regions: Alpine, Dinaric,
Najdeno v: osebi
Ključne besede: apple juice, geographical origin, agricultural production practice, biomarkers, phenol compounds, elements, stable isotopes, Slovenia
Objavljeno: 07.06.2016; Ogledov: 3403; Prenosov: 352
.pdf Polno besedilo (3,97 MB)

12.
Polyphenol, antioxidant and antimicrobial potential of six different white and red wine grape processing leftovers
Peter Raspor, Sonja Smole Možina, Katja Jug, Melita Sternad Lemut, Branka Mozetič Vodopivec, Anja Klančnik, Kajetan Trošt, 2016, izvirni znanstveni članek

Opis: BACKGROUND During winemaking, grape polyphenols are only partly extracted, and consequently unexploited. The main aim was to characterise the phenolic content of freeze-dried grape skin and seed (FDSS) extracts obtained from Slovenian and international grape varieties and evaluate their antioxidant, antimicrobial, and anti-adhesive activities. RESULTS FDSS of six Vitis vinifera L. grapevine cultivars from Vipava Valley region (Slovenia) underwent extraction and sonification under different conditions. Flavonols were the predominant content of extracts from white ‘Zelen’ and ‘Sauvignon Blanc’ grape varieties, with strong antimicrobial activities against Gram-negative bacteria. ‘Pinot Noir’ FDSS extracted with 50% aqueous ethanol extraction produced a high phenolic content in the final extract, which was further associated with strong antioxidant and antimicrobial activities against all tested bacteria. Bacterial adhesion to stainless steel surfaces with minimal and maximal surface roughness was significantly inhibited (up to 60%) across a wide FDSS concentration range, with lower concentrations also effective with two types of stainless steel surfaces. CONCLUSION FDSS extracts from winery by-products show interesting phenolic profiles that include flavonols, catechins, anthocyanins, and hydroxycinnamic acids, with yields influenced by grapevine cultivar and extraction conditions. The antioxidant, antimicrobial and anti-adhesive activities of 50% aqueous ethanol ‘Pinot Noir’ FDSS extract reveals potential applications in food, pharmaceutical and cosmetic industries for these bioactive residues.
Najdeno v: osebi
Ključne besede: grape skins and seeds, extraction solvents, phenolic profile, antioxidant activity, antimicrobial activity, anti-adhesion activity to stainless steel
Objavljeno: 08.08.2016; Ogledov: 1913; Prenosov: 0
.pdf Polno besedilo (2,02 MB)

13.
Vpliv različnih bentonitov na senzorične in kemijske lastnosti vina sorte 'Rebula' (Vitis vinifera L.)
Uroš Špacapan, 2018, diplomsko delo

Opis: Pomemben dejavnik pri kakovosti vina ter posledično tudi pri uspešni prodaji je stabilnost vina v steklenici, kajti v nasprotnem primeru pride do slabega ugleda vinarja in tudi zavračanja proizvoda na trgu. Beljakovinsko stabilnost vina lahko dosežemo na več načinov, ki pa so odvisni od same tehnologije in tudi trendov na vinskem trgu. V sklopu diplomske naloge smo preučevali vpliv uporabe štirih različnih bentonitov na kemijske in senzorične lastnosti vina sorte Rebula. Vino smo pred stekleničenjem tretirali z različnimi komercialno dostopnimi bentoniti in stekleničena vina kemijsko ter senzorično ovrednotili. Poleg določanja osnovnih kemijskih parametrov smo spektrofotometrično določili vsebnost skupnih fenolov in barve vina. S pomočjo encimskih kitov smo določili tudi vsebnost vinske, jabolčne in mlečne kisline v stekleničenih vinih. Rezultati našega poskusa kažejo, da je uporaba različnih bentonitov vplivala tako na kemijske kot tudi na senzorične lastnosti vina. V vinih tretiranih z bentonitom smo zaznali rahel trend nižjih vsebnosti alkohola ter skupnih titrabilnih in hlapnih kislin. Obenem pa smo zaznali tudi trende povečanja parametrov, kot je barva vina (absorbanca pri 420 nm) in vsebnosti skupnih fenolov primerjavi s kontrolnim – netretiranim vzorcem. Senzorična ocena tretiranih vin je nakazala trend siromašenja sadnih not pri vseh uporabljenih bentonitih, v določenih primerih pa, nasprotno, pozitivne vplive na zaznane cvetlične in rastlinske note. Rezultati so tako pokazali, da vrsta bentonita različno vpliva na senzorične lastnosti vina Rebula.
Najdeno v: osebi
Ključne besede: vino Rebula, belo vino, bentonit, kemijski parametri vina, senzorične lastnosti vina
Objavljeno: 13.02.2018; Ogledov: 1286; Prenosov: 106
.pdf Polno besedilo (1,62 MB)

14.
PRIPRAVA IN SENZORIČNA OCENA AROMATIZIRANEGA VINJAKA
Tina Žorž, 2018, diplomsko delo

Opis: V diplomskem delu smo obravnavali vpliv dodane naravne arome karamela na senzorične lastnosti vinjaka. V staran vinjak smo dodali 3 različne koncentracije naravne arome karamela, ki smo jo dobili na trgu v prosti prodaji. Aroma je namenjena tako živilskim kot tudi farmacevtskim izdelkom in vsebuje naravne komponente arome karamela. Senzorično oceno smo izvedli s pomočjo uradnega panela Kmetijsko gozdarskega zavoda Nova Gorica in ocenjevalnega lista, ki smo ga povzeli iz literature. V okviru senzorične ocene je ocenjevalna komisija pripravljene vzorce ocenjevala z opisno analizo in kvalifikacijsko analizo. Med potrošniki pa smo izvedli tudi test všečnosti. Rezultati diplomske naloge nakazujejo, da dodatek izbrane naravne arome karamela vinjaku v najnižji koncentraciji (5 ml/l), ki smo ga uporabili v diplomski nalogi, najbolje pripomore k boljši aromatiki in zaokroženemu okusu. Opazili smo, da dodatek arome v vinjak navkljub odsotnosti sladkorja pripomore k večji zaznavi sladkosti v okusu in k zakrivanju zaznavanja alkohola, kar je najverjetneje botrovalo preferenčnim razlikam med moškim in ženskim okusom do izbranih alkoholnih pijač. Ženske in mlajše generacije so se na splošno odločale za bolj aromatizirane vzorce, moške pa sta bolj prepričala osnovni vzorec in vzorec z majhnim dodatkom karamele.
Najdeno v: osebi
Ključne besede: vinjak, aroma karamele, senzorična ocena, analiza potrošnikov
Objavljeno: 30.07.2018; Ogledov: 1461; Prenosov: 84
.pdf Polno besedilo (1,97 MB)

15.
Uporaba različnih kvasovk v pridelavi jabolčnega vina
Luka Koporec, 2018, diplomsko delo

Opis: Kemijske in senzorične lastnosti vina so poleg genetskih danosti ter geo-klimatskih okoliščin odvisne tudi od strategije tehnologije pridelave, ki jo izbere vinar. V to strategijo spada tudi izbira seva kvasovke. Vinski trg postaja vse bolj zahteven in željan nečesa novega, zato vse več vinarjev poskuša pridobiti drugačne lastnosti vin z uporabo drugačnih sevov kvasovk, oziroma z uporabo kombinacij različnih vrst kvasovk. V diplomski nalogi smo preučevali vpliv različnih kombinacij kvasovk na potek fermentacije ter na osnovne kemijske in senzorične lastnosti pridelanega jabolčnega vina. Poskus je bil izveden na laboratorijski skali. Rezultati poskusa so pokazali, da različne vrste kvasovk različno vplivajo na senzorične lastnosti vina, nekoliko manj pa na kemijske lastnosti. Rezultati nakazujejo, da različne kvasovke različno hitro porabljajo sladkorje, kar vpliva tudi na hitrost poteka fermentacije. Ob opazovanju osnovnih kemijskih lastnostih smo opazili razlike med kvasovkami oz. kombinacijami kvasovk pri parametrih kot so hlapne kisline in reducirajoči sladkorji, medtem ko v vsebnosti alkohola in pH vrednostih končnih jabolčnih vin med obravnavanimi fermentacijami nismo opazili razlik. Senzorična analiza vonja in barve jabolčnih vin je potrdila vpliv kvasovk na barvo, intenzivnost, trajnost in vrsto vonja.
Najdeno v: osebi
Ključne besede: jabolčno vino, ne-Saccharomyces kvasovke, potek fermentacije, kvasovke, senzorična analiza
Objavljeno: 26.10.2018; Ogledov: 741; Prenosov: 51
.pdf Polno besedilo (1,34 MB)

16.
Phenolic Contents and Postharvest Quality Changes of Norwegian ‘Mallard’ plums (Prunus domestica L.) as a Consequence of Delayed Time to Low Temperature Storage
Eivind Vangdal, Alena Gibalova, Branka Mozetič Vodopivec, 2012, objavljeni znanstveni prispevek na konferenci

Opis: During the picking season in the Norwegian plum production areas, the harvested plums are brought to cold storage in packing houses once or twice a day. Plums picked late in the afternoon may even not be cooled properly until the next day. The average time from picking until the plums are placed in a cold storage is approximately 8 hours. Previous reports have shown that delayed cooling of sweet cherries and apples reduced the fruits’ susceptibility to physiological or fungal decay. An experiment was performed in order to evaluate the impact of different delay-to-cold storage times (0, 5, 10, 15 and 25 hours) on quality and phenolic contents changes of Norwegian ‘Mallard’ plums during cold storage, transport, and retail in normal atmosphere (NA). The fruits (10 fruits in PE tray, n=3) were stored for 14 days at 1°C, followed by 3 days at 7°C and then for 4 days at 20°C. Fruit quality parameters (firmness, colour in CIE L, a*, b* colour space, weight, rot occurrence (%)) and total phenol and anthocyanin content were determined. Samples were analyzed just before cold storage and then after 14 days at 1°C, 3 days at 7°C, or 4 days at 20°C. Evaluation of results has shown that delay of cooling has a retarding effect on rot development during 20°C storage (post cold transport), weight loss and stimulates anthocyanin accumulation and colour changes to some extent. At the end of storage no effect on fruit firmness could be observed.
Najdeno v: osebi
Ključne besede: anthocyanins, total phenols, colour, rot, firmness, postharvest, plums, cold storage
Objavljeno: 11.11.2016; Ogledov: 1714; Prenosov: 0
.pdf Polno besedilo (268,22 KB)

17.
Determination of bioactive compounds in food samples by thermal lens microscopy
Mladen Franko, Dorota Korte Kobylinska, Branka Mozetič Vodopivec, Valeria Guzsvány, Mojca Žorž, Jelena Topič, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: thermal lens microscopy, food samples, bioactive compounds
Objavljeno: 08.11.2016; Ogledov: 1730; Prenosov: 0
.pdf Polno besedilo (516,89 KB)

18.
The comparison of anthocyanin and pyranoanthocyanin extraction efficiency in Pinot Noir wine using SPE
Branka Mozetič Vodopivec, Dorota Korte, Jelena Topić, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: Anthocyanins, wine, Pinot Noir, HPLC, solid-phase extraction
Objavljeno: 05.07.2017; Ogledov: 1171; Prenosov: 0
.pdf Polno besedilo (109,24 KB)

19.
Biodiversity of cider yeasts and their cider-making potential
Lorena Butinar, Branka Mozetič Vodopivec, Melita Sternad Lemut, Eivind Vangdal, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: In the area of Hardanger, a part of the fjord region in Western Norway, the production of apple wine (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. By tradition cider is produced by a spontaneous fermentation process of apple juice, performed by naturally occurring indigenous yeasts that originate from the fruit or the surfaces of the processing equipment. Therefore, our aim was primarily to study the ecology and biodiversity of the yeasts associated with the production of traditional cider in the Hardanger area. For two consecutive years, we sampled at 11 different locations in the observed region, where we collected cider samples and surface swabs of processing facilities from the cideries, and also soil and various parts of apple trees in orchards owned by the same producers. Thus, by enriching collected samples with the selective medium with high sugar and ethanol concentration, we managed to isolate about 1,300 yeasts. Based on the multiplex PCR results the yeasts were grouped into the Saccharomyces sensu stricto complex and non-Saccharomyces yeasts. The isolates were determined to the species level by performing the restriction analysis of ITS PCR products, and in some cases identifications were confirmed by sequencing of the D1/D2 domain of the 26S rDNA and/ or ITS region. As expected, non-Saccharomyces yeasts from the genus Metschnikowia and Hanseniaspora mainly populated the orchards, while the Saccharomyces yeasts were isolated in the orchards from the soil and fruits. In contrast, in ciders the species S. uvarum was predominantly found, occasionally also S. cerevisiae, Torulaspora delbrueckii and P. membranifacies. Indigenous cider yeasts were further on characterized in micro-plate format for the most important cider-making technological parameters (tolerance to ethanol, SO2, growth at low pH), for the presence of glucoside hydrolase activity, H2S production ability, and assimilation of malic acid. Based on this screenings the micro-scale fermentations of apple juice were performed with 13 different indigenous cider yeasts as monocultures. The most promising indigenous yeasts, T. delbrueckii and S. uvarum, were also tested as mixed cultures in sequential fermentations. Since the tested strain of T. delbrueckii as monoculture was not able to complete the alcoholic fermentation, better results were obtained in sequential fermentation with the mixed culture in combination with S. uvarum.
Najdeno v: osebi
Ključne besede: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making
Objavljeno: 08.11.2017; Ogledov: 1361; Prenosov: 0
.pdf Polno besedilo (10,33 MB)

20.
BIOTSKA RAZNOVRSTNOST KVASOVK POVEZANIH S PROIZVODNJO JABOLČNEGA VINA
Eivind Vangdal, Melita Sternad Lemut, Branka Mozetič Vodopivec, Lorena Butinar, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Na območju fjorda Hardanger, del zahodne Norveške, ima proizvodnja jabolčnega vina dolgo tradicijo in sicer sega v 12. stoletje, ko so menihi na tem območju začeli uvajati sadjarstvo. Danes je to glavno območje pridelovanja sadja na Norveškem. Kljub strogi regulativi proizvodnje alkoholnih pijač, pa se je na tem območju na nekaterih kmetijah ohranila tradicionalna proizvodnja jabolčnega vina. Namen naše študije je bil predvsem preučiti ekologijo in biotsko raznovrstnost kvasovk, ki so povezane s proizvodnjo tradicionalnega jabolčnega vina na območju Hardanger. Na tem območju smo tekom dveh zaporednih let vzorčili na 11-ih različnih lokacijah, kjer smo pri proizvajalcih vzorčili jabolčno vino, tla in različne dele jablan v sadovnjakih. Tako smo s pomočjo bogatitve v gojišču s povišanim sladkorjem in etanolom osamili približno 1300 izolatov kvasovk. Kvasovke smo s pomočjo multipleks PCR testa ločili na skupino kompleksa Saccharomyces sensu stricto in ne-Saccharomyces kvasovke. Nadalje smo izolate določili do nivoja vrste z izvedbo restrikcijske analize ITS PCR produktov, v nekaterih primerih smo za potrditev identifikacij opravili še določitev nukleotidnih zaporedij D1/D2 domene 26S rDNA. Kot pričakovano smo ugotovili, da sadovnjake naseljujejo predvsem ne-Saccharomyces kvasovke iz rodov Metschnikowia in Hanseniaspora, v tem okolju so bile Saccharomyces izolirane iz tal in jabolk. V jabolčnem vinu pa je bila pretežno izolirana vrsta S. uvarum, občasno pa tudi S. cerevisiae, Torulaspora delbrueckii in P. membranifacies.
Najdeno v: osebi
Ključne besede: kvasovke, biotska raznovrstnost, jabolčno vino
Objavljeno: 09.11.2017; Ogledov: 1093; Prenosov: 0
.pdf Polno besedilo (334,39 KB)

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