1. Biodiversity of cider yeasts and their cider-making potentialLorena 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: ključnih besedah Ključne besede: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making Objavljeno: 08.11.2017; Ogledov: 5157; Prenosov: 0
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2. Validacija HPLC metode za določanje organskih kislin in sladkorjev v vinuKristjan Mesar, 2022, diplomsko delo Opis: 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. Najdeno v: ključnih besedah Ključne besede: vino, cider, HPLC, UV, RID, organske kisline, sladkorji, validacija Objavljeno: 02.08.2022; Ogledov: 806; Prenosov: 45
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3. Cider yeasts associated with Hardanger cider during fermentation processLorena Butinar, Ingunn Ovsthus, Branka Mozetič Vodopivec, Mitja Martelanc, Urban Česnik, 2022, objavljeni povzetek znanstvenega prispevka na konferenci Opis: 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. Najdeno v: ključnih besedah Ključne besede: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making Objavljeno: 18.10.2022; Ogledov: 415; Prenosov: 0
Polno besedilo (136,08 KB) |
4. Hkratna določitev amino kislin in biogenih aminov v vzorcih jabolčnega soka, ciderja in vina s HPLC-UVBranka Mozetič Vodopivec, Memlita Sternad Lemut, Lorena Butinar, Urban Česnik, Tatjana Radovanović vukajlović, Mitja Martelanc, 2022, objavljeni znanstveni prispevek na konferenci Najdeno v: ključnih besedah Ključne besede: Cider, vino, jabolčni sok, HPLC-UV, Amino kisline, biogeni amini. Objavljeno: 20.02.2023; Ogledov: 251; Prenosov: 0
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5. Simultaneous determination of chemical parameters for wine and cider quality control using HPLC-UV/RI system based on reverse-phase separation capabilitiesMitja Martelanc, 2022, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje) Najdeno v: ključnih besedah Ključne besede: HPLC-UV-RI, Cider, Wine, Must, Organic aacids, Ethanol, Glucose, Fructose. Objavljeno: 20.02.2023; Ogledov: 207; Prenosov: 0
Polno besedilo (16,55 MB) |