Vpliv kaolina na kakovost grozdja in vina žlahtne vinske trte (Vitis vinifera L.) sorte 'Refošk'

Hoblaj, Sara (author), Mikulič Petkovšek, Maja (mentor)

Zaradi podnebnih sprememb se srečujemo z vedno daljšimi obdobji suše, ki lahko negativno vplivajo na kakovost grozdja in vina žlahtne vinske trte (Vitis vinifera L.). V letu 2021 smo v Baredih na sorti 'Refošk' preizkušali učinkovitost kaolina pri zmanjšanju sušnega stresa in njegov vpliv na kakovost grozdja in vina. Predvsem nas je zanimalo, kako tretiranje s kaolinom vpliva na vsebnosti sekundarnih metabolitov v grozdju in posledično tudi vinu. Kaolin smo na trte nanesli trikrat: 31. 7. (30 g/L), 14. 8. (20 g/L) in 28. 8.2021 (20 g/L). V poskus je bilo vključenih 25 tretiranih trt s kaolinom in 25 trt, ki so predstavljale kontrolo (tretiranje z vodo). Poskus je bil izveden v 10 blokih, petkontrolnih in pet tretiranih s kaolinom. V tehnološki zrelosti smo opravili trgatev in grozdje odpeljali v klet. V kleti smo jagode ločili od pecljevine, jih drozgaliter naredili prve analize. Nato smo pričeli z mikrovinifikacijo, ki je potekala 24 dni pri temperaturi 18 °C. Vsakodnevno smo spremljali potek fermentacije in potapljali klobuk. Po končani maceraciji smo vino pretočili in pustili, da povre do konca. Po končani fermentaciji smo vino žveplali in stekleničili ter naredili zaključne analize. Analize so bile narejene na WineScanTM, spektrofotometru in HPLC. Po statistični obdelavi podatkov smo ugotovili, da med kontrolo in kaolinom ni statistično značilnih razlik v vsebnosti skupnih sladkorjev, skupnih kislin, fenolnih spojin in drugih proučevanih parametrih v grozdju. Tudi pri vinu ni bilo statistično značilnih razlik med kontrolo in kaolinom. Zaključili smo, da kaolin nima negativnega vpliva na kakovost grozdja in vina.

• Language: Slovenian
• Keywords: vinogradništvo, Vitis vinifera, 'Refošk', kaolin, sekundarni metaboliti, antocianini
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: [S. Hoblaj]
• Year: 2022
• PID: 20.500.12556/RUL-135032
• UDC: 634.8:549.623.9:632.112:543.61(043.2)
• COBISS.SI-ID: 97954051
• Publication date in RUL: 18.02.2022

HOBLAJ, Sara, 2022, Vpliv kaolina na kakovost grozdja in vina žlahtne vinske trte (Vitis vinifera L.) sorte “Refošk” [online]. Master’s thesis. Ljubljana : S. Hoblaj. [Accessed 5 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=135032

Secondary language

• Language: English
• Title: The impact of kaolin on grape and wine quality of the grapevine variety (Vitis vinifera L.) 'Refošk'

Abstract

Due to climate change, we are facing increasingly long periods of drought, which can have a negative impact on the quality of grapes and wine of the grapevine (Vitis vinifera L.). In 2021, we tested the effectiveness of kaolin on the variety 'Refošk' and its effect on reducing drought stress and the impact on the quality of grapes and wine. The experiment was conducted in Baredi, Slovenia. We were particularly interested in the effect of kaolin treatment on the content of secondary metabolites in grapes and consequently in wine. Kaolin was applied to the vines three times: on July 31 (30 g/L), on August 14 (20 g/L), and on August 28 (20 g/L). The trial included 25 vines treated with kaolin and 25 vines representing the control plot. The trial was conducted in 10 blocks, five control blocks and five kaolin treated blocks. At the time of technological maturity, we harvested the grapes and took them to the cellar. In the cellar we separated the berries from the stems, squeezed them and performed the first analyses. The process of microvinification took place for 24 days at 18 °C. We monitored the fermentation process daily and soaked the berry skins. After maceration, we poured off the wine and left it to ferment until the end. After fermentation, the wine was sulfurized and bottled while the final analyses were performed. The analyses were performed with the WineScanTM, a spectrophotometer and HPLC. After statistical analysis of the data, we found no statistically significant differences between the control samples and the samples treated with kaolin, in terms of the content of total sugars, total acids, phenolic compounds and other parameters studied in the grapes. There were also no statistically significant differences in the parameters measured in the control wine and the wine treated with kaolin. Therefore, we conclude that kaolin has no negative effects on the quality of grapes and wine.

• Keywords: viticulture, Vitis vinifera, 'Refošk', kaolin, secondary metabolites, anthocyanins