diplomsko delo
Veronika Frelih (Author), Denis Rusjan (Mentor)

Abstract

Neznačilen starikav ton (NST) je napaka vina, ki se pojavi po zaključeni alkoholni fermentaciji že po nekaj mesecih ali po letu od prvega žveplanja. Prvič so o tej napaki vina poročali v Nemčiji, v zgodnjih 80. letih prejšnjega stoletja. Pojavi se tako pri vinih iz sort žlahtne vinske trte Vitis vinifera L., kot tudi pri interspecifičnih sortah vinske trte. Na nastanek napake NST vina vplivajo stresne rastne razmere za trto v vinogradu, kot tudi otežena alkoholna fermentacija. Bele sorte vinske trte, kot so 'Laški Rizling', 'Renski Rizling', 'Istrska Malvazija' in 'Chardonnay' v do sedaj opravljenih študijah kažejo večjo nagnjenost k tvorbi napake NST. Tovrstna vina prehitro izgubijo sortno značilne arome, hkrati pa se razvijejo arome, ki spominjajo na akacijeve cvetove, naftalin, umazano krpo ter mokro volno. Vina na okus delujejo prazna, z večjo zaznavo grenkobe in trpkosti. Spojina, ki se jo povezuje z NST vina, je 2-aminoacetofenon (2-AAP), ki nastane zaradi razpada indol-3-ocetne kisline (IAA). Slednja izvira tako iz grozdja, kot tudi iz metabolizma kvasovk. Glede na vsebnost IAA v grozdnem soku, ne moremo sklepati na končno vsebnost 2-AAP v vinu. Senzorični prag zaznave 2-AAP je med 0,5 in 1,5 μg/l. K hitrejši senzorični zaznavi NST stekleničenega vina pripomorejo tudi neugodne razmere zorenja vina. Začasni preventivni ukrepi zoper napako NST vina je dodatek askorbinske kisline, ki mora biti natančno odmerjen. Kljub prisotnim stresnim rastnim razmeram, ki nadaljnje vplivajo na tvorbo napake vina, je želja vsakega pridelovalca grozdja in vina, te dejavnike ublažiti z vinogradniškimi in vinarskimi ukrepi, ter tako preprečiti nagnjenost sorte k tvorbi napake, ter vinu obdržati in podaljšati kakovost.

Keywords

vinogradništvo;vinarstvo;vinograd;vinifikacija;kakovost;grozdje;vino;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [V. Frelih]
UDC: 634.8(043.2)
COBISS: 9020025 Link will open in a new window
Views: 776
Downloads: 427
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Other data

Secondary language: English
Secondary title: Viticultural and winemaking conditions for atypical aging of the white wines
Secondary abstract: Atypical aging (ATA), also known as untypical aging, is an off-flavor that can occur within a period of few weeks to one year after the first addition of sulfur dioxide postfermentation. It has been first reported in Germany, in the early 1980s. ATA can occur in wines made from Vitis vinifera L. vine varieties and from the interspecific vine varieties. It is generally accepted that the ultimate cause of ATA are stressful growth conditions in the vineyard, as well as stress reactions during alcoholic fermentation. White vine varieties, such as 'Welschriesling', 'Riesling', 'Istrska Malvazija' and 'Chardonnay' show a greater propensity to form ATA. Such wines show lack of varietal aroma compounds, while at the same time, aromas reminiscent of acacia flowers, naphthalene, dirty dish rag and wet wool develop. Wines seem meager and thin, with greater perception of bitterness and astringency. 2-aminoacetophenone (2-AAP) is one of the major odor-active compound responsible for the off-flavor. AAP is generated by degradation of indole-3-acetic acid (IAA). IAA originates both from the grapes and from the yeast. By the IAA content in the must given, we can not deduce the final content of 2-AAP in the wine. The sensory detection threshold of 2- APP in wine is between 0.5 and 1.5 μg/l. Faster sensory recognition and development of 2-AAP in bottled wine is also contributed by unfavorable conditions of maturing the wine. Addition of ascorbic acid to the wine is a temporary solution. Despite the stressful growing conditions that influence the formation of ATA in wine, the desire of every winegrower is to alleviate these factors by right viticultural and winemaking measures, thus preventing the wine's tendency to form ATA and prolong its quality.
Secondary keywords: viticulture;winemaking;vineyard;vinification;quality;grapes;wine;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za agronomijo
Pages: VI, 23 str.
ID: 10955690