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Vpliv interaktivnih kvasovk na fizikalno-kemijsko sestavo in kakovost rdečega vina 'Merlot'
David Rustja, 2012, undergraduate thesis

Found in: osebi
Keywords: diplomske naloge, vino, Merlot, Vipavska dolina, polifenoli, antociani, proantocianidini, senzorična ocena
Published: 15.10.2013; Views: 5145; Downloads: 444
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Polifenolni profil grozdja sorte 'Refošk' (Vitis vinifera) letnika 2011 na Krasu
Borut Hrovatin, 2014, undergraduate thesis

Found in: osebi
Keywords: diplomske naloge, Refošk, Kras, antocianini, HPLC, spektrofotometer
Published: 25.04.2014; Views: 6292; Downloads: 339
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Vpliv kisika in hrastovih nadomestkov na fizikalno-kemijsko sestavo in kakovost rdečega vina 'Refošk'
Iztok Kavrečič, 2014, undergraduate thesis

Found in: osebi
Keywords: diplomske naloge, Refošk, kisik, hrastovi nadomestki, mikrooksigenacija, polifenoli, senzorična analiza
Published: 25.04.2014; Views: 6071; Downloads: 425
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Combined effects of early season leaf removal and climatic conditions on aroma precursors in ‘Sauvignon blanc’ grapes
Andreja Vanzo, Paolo SABBATINI, Klemen Lisjak, Marijan Bubola, Melita Sternad Lemut, Lorena Butinar, Branka Škvarč, Jose Carlos HERRERA, Rachele FALCHI, Paolo Sivilotti, 2017, original scientific article

Abstract: Early leaf removal around the cluster zone is a common technique applied in cool climate viticulture, to regulate yield components and improve fruit quality. Despite the increasing amount of information on early leaf removal and its impact on total soluble solids, anthocyanins and polyphenols, less is known regarding aroma compounds. In order to verify the hypothesis that defoliation, applied before or after flowering, could impact the biosynthesis of thiol precursors, we performed a two year (2013 and 2014) experiment on Sauvignon blanc. We provided evidence that differential accumulation of thiols precursors in berries is affected by the timing of defoliation and this impact was related to modifications in biosynthetic pathway. Furthermore, the possible interaction between leaf removal treatment and seasonal weather conditions, and its effect on the biosynthesis of volatile precursors are discussed. Our results suggested that in Sauvignon blanc the relative proportion of 4-S-glutathionyl-4-methylpentan-2-one (G-4MSP) and 3-S-glutathionylhexan-1-ol (G-3SH) precursors can be affected by defoliation, and this could be related to the induction of two specific genes encoding glutathione-S-transferases (VvGST3 and VvGST5), while no significant effects on basic fruit chemical parameters, polyphenols and methoxypyrazines were ascertained under our experimental conditions.
Found in: osebi
Keywords: early leaf removal, cluster exposure, thiol precursors, methoxypyrazines, glutathione S-transferase, Vitis vinifera
Published: 31.08.2017; Views: 3507; Downloads: 0
.pdf Fulltext (1,04 MB)

Occurence of biogenic amine - producing lactic acid bacteria in Refošk grape and wine
Jelena Topić Božič, Jan Reščič, Martina Bergant Marušič, Klemen Lisjak, Branka Mozetič Vodopivec, Lorena Butinar, 2019, published scientific conference contribution abstract

Abstract: Lactic acid bacteria (LAB) are naturally present in grapes, musts and wines. During malolactic fermentation, besides the beneficial conversion of L-malic to L-lactic acid, LAB can form also other compounds like biogenic amines (BAs). BAs are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing BAs can lead to food poisoning such as histamine poisoning. Histamine, the most studied BA, is known to cause headaches, oedema, vomiting. In the last years, BAs associated pathways have been described as strain dependent and not as species dependent. Because of the high variability of microorganisms to decarboxylase amino acids, the detection of bacteria that have the possibility to transform precursor amino acid into BAs is very important in order to estimate the risk of BAs accumulation in wines. Since in previous years during project AGROTUR I we detected the higher BA content in some wines, we decided to focus on the presence of BA-producing LAB in Refošk grapes and wines. Therefore, during AGROTUR II project LAB collection of autochthonous lactic acid bacteria was set-up by isolating LAB from Refošk grapes and wines, originated from the grape growing cross-border region Karst (Slovenia). Over 600 isolates were obtained using MRS medium with added cycloheximide and 2% tomato juice. In parallel, also selective enrichment was performed using MRS medium described above with additionally added 5% ethanol. BA-producing LAB were primarily detected in microtiter-plate format using the decarboxylase screening medium with added amino acids (histidine, lysine, ornithine or tyrosine), which enable us to identify histamine-, cadaverine-, ornithine and tyrosine-producing LAB. Selected representatives from each BA-producing LAB groups were further on confirmed with chromatographic analysis (HPLC) and molecular methods (multiplex PCR method). BA-producing LAB were in majority represented by thyramin-producers, thereafter followed cadaverine-producers, with putrescine and histamine producers being the least presented. This screening of the BA-producing LAB is also incorporated in our on-going accurate selection of LAB starters for potential production of Refošk wines.
Found in: osebi
Keywords: biogenic amines, lactic acid bacteria, refošk, grape, wine
Published: 22.01.2020; Views: 2488; Downloads: 0
.pdf Fulltext (185,72 KB)

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