Odvisnost pojava reduktivnih not v penečih vinih glede na prehranjenost kvasovk vrste Saccharomyces bayanus

Kejžar, Veronika (author), Košmerl, Tatjana (mentor)

Hlapne žveplo vsebujoče spojine v vinu, imenovane tudi reduktivne spojine vina, predstavljajo velik problem v vinarstvu, saj so krivec skoraj 30 % vseh napak v pridelavi vin. Namen magistrskega dela je bil ugotoviti, ali koncentracije lahko hlapnih žveplovih spojin, predvsem vodikovega sulfida (H2S), variirajo glede na dodano količino in vrsto dušikovih hranil za kvasovke tekom sekundarne alkoholne fermentacije in ali bodo koncentracije žveplovih spojin s časom naraščale. V fermentacijskih poskusih smo uporabili osnovni vini sorte muškat ottonel (za muškatno penino) in kombinacijo vin sorte chardonnay in beli pinot (za penino sec), ki smo jih razdelili v štiri fermentacijske tanke, tekom sekundarne alkoholne fermentacije pa smo v dva tanka dodali tri enake odmerke različnih dušikovih hranil, in sicer enostavno in kompleksno hranilo. Vino smo med procesom sekundarne alkoholne fermentacije vzorčili in zamrznili do nadaljnih analiz s tehniko nadprostora (angl. Headspace), kjer smo kvantitativno določili vsebnosti hlapnih žveplovih spojin v vzorcih penin, predvsem H2S. Rezultati so pokazali, da se je izmed hlapnih žveplovih spojin v penini tvoril le H2S, čigar koncentracija se je tekom alkoholne fermentacije zmanjševala do vsebnosti, ki za človeka niso več zaznavne (izjema je vzorec penine sec, pri kateri hranil tekom sekundarne alkoholne fermentacije nismo dodajali). Pri peninah, v katere smo hranila dodajali, smo bili priča hitrejšemu zaključku alkoholne fermentacije, medtem ko bistvenih razlik med uporabljenim enostavnim ali kompleksnim hranilom, glede na končno vsebnost H2S v vzorcih, ni bilo.

• Language: Slovenian
• Keywords: vino, penina, vinske kvasovke, sekundarna alkoholna fermentacija, hlapne žveplove spojine, reduktivne spojine, vodikov sulfid, hranila za kvasovke
• Work type: Master's thesis/paper
• Organization: BF - Biotechnical Faculty
• Publisher: [V. Kejžar]
• Year: 2019
• PID: 20.500.12556/RUL-113425
• UDC: 663.223:582.282.23:663.252.4:543.9
• COBISS.SI-ID: 5141368
• Publication date in RUL: 02.01.2020

Secondary language

• Language: English
• Title: Dependence of the appearance of reductive notes in sparkling wines according to the nutrition of yeast Saccharomyces bayanus

Abstract

Reduced malodors are one of the most common faults observed in modern commercial wines – they are reported to be responsible for approximatelly 30 % of all wine faults worldwide. The purpuse of this Master's thesis was to determine whether the addition of different nitrogen nutrients for yeasts during the secondary fermentation of sparkling wines, effects on final quantity of volatile sulfur compounds (VSCs), especially hydrogen sulfide (H2S). In the experiments conducted we have used the base wines made of muscat ottonele (for muscat sparkling wine) and combination of chardonnay and pinot blanc for sparkling wine sec. The wines were split in four wine tanks, two of each were added the same amounts of different yeast nutrients (anorganic and an organic yeast nutrient). The wine samples were collected and analised with headspace techinque. This research provided new findings regarding reduced malodors concentrations in sparkling wines. Firstly, out of all VSCs only H2S was produced in sparkling wines. In addition, the concentration of H2S was gradually reduced during secondary fermentation up to a point of not being detected anymore. Secondly, differences in fermentation process in regards to nutrient addition were observed. Fermentation stopped earlier in wines with added nutrients, when comparing to those without. In addition, no significant differences in H2S concentrations were observed between wines with added anorganic and an organic yeast nutrients.

• Keywords: wine, sparkling wine, wine yeasts, secondary fermentation, volatile sulfur compounds, reductive aromas, hydrogen sulfide, yeasts nutrients