Influence of grape yield on aroma of Malvasia istriana wine

Svrha ovog rada bila je proučiti utjecaj različitih prinosa grožđa na aromu vina Malvazija istarska. Prilikom rezidbe u vinogradu je odabrano po četrneast trsova, na kojima je ostavljeno dvadeset, odnosno četrdeset pupova. Različiti broj pupova rezultirao je različitim prinosom (7194 kg/ha i 9994 kg/ha), kao i razlikom u kakvoći grožđa s obzirom na izmjereni šećer, ukupnu kiselost i pH vrijednost. Grožđe je ubrano u vrijeme tehnološke zrelosti te je klasičnom obradom prerađeno u mošt. Nacjepljen je selekcionirani kvasac Saccharomyces cerevisiae i praćena je promjena lako hlapljivih tvari arome (viši alkoholi, esteri i karbonilni spojevi) tijekom alkoholne fermentacije i u vinu. Određivanje kvantitativnog i kvalitativnog udjela hlapljivih tvari arome provedeno je metodom plinske kromatografije (GC), a za pripremu uzorka korištena je metoda statičkog headspace uzorkovanja (SHS). Utvrđen je porast svih identificiranih spojeva tijekom alkoholne fermentacije i u vinu u odnosu na mošt. Usporedbom hlapljivih tvari arome tijekom fermentacije utvrđen je veći udjel svih tvari arome kod uzorka s prinosom od četrdeset pupova po trsu. U proizvedenim vinima nije utvrđena značajna razlika u udjelu tvari arome.The aim of this work was to study the influence of different grape yields on aroma of Malvasia istriana. During the pruning in the vineyard fourteen grape-vines were selected on which twenty, actually forty buds were kept. The different number of buds caused not only different yields (7194 kg/ha and 9994 kg/ha), but also a difference in the grape quality concerning the measured sugar, the acidity and the total pH value. The grapes were picked at the time of their technological ripeness, and then they were classically transformed into grapejuice. The selected yeast Saccharomyces cerevisiae was inoculated and the change of volatile aroma supstances (higher alcohols, esters and carbonylic compounds) was observed during the alcoholic fermentation and in the wine. The determination of the quantitative and qualitative amount of volatile aroma compounds was done using the method of gas chromatography (GC), and the method of static headspace sampling (SHS) was used in the preparation of the sample. There was established the increase of all the identified compouds during the alcoholic fermentation and in the wine. Comparing volatile compounds of the sample with the yield of twenty and forty buds there was established a bigger amount of all the volatile aroma compounds in the sample with the yield of forty buds. Comparing the wine samples there wasn't established an important difference in the share of volatile aroma compounds in the samples with twenty and forty buds