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  • Lukić, Igor

    12/2008
    Web Resource

    Okarakterizirane su sortne rakije komovice proizvedene tradicionalnim načinom destilacije komine najznačajnijih sorti grožda u Istri, i to na osnovi sastava hlapivih spojeva arome. U proizvedenim rakijama komovicama te u različitim frakcijama destilata, kombiniranom tehnikom plinske kromatografije i spektrometrije masa (GC/MS), identificirani su najvažniji spojevi primarne i sekundarne arome (terpeni, C13-norizoprenoidi, viši alkoholi, masne kiseline, esteri, aldehidi, ketoni, te acetali), dok su njihovi udjeli određeni tehnikom plinske kromatografije uz plamenoionizacijski detektor (GC/FID). Uporabom statističkih metoda analize utvrđene su razlike u sastavu hlapivih spojeva arome između rakija komovica od različitih sorti. Provedeno je i senzorsko ocjenjivanje rakija DLG metodom, te su utvrđene korelacije između udjela spojeva arome i senzorske kvalitete. Zaključeno je da osnovu arome svih sortnih rakija komovica uključenih u istraživanje čine najvažniji spojevi sekundarne arome: viši alkoholi, hlapive masne kiseline, hlapivi esteri, te acetaldehid, a u pojedinim slučajevima i 1-heksanol. Viši udjeli većine spojeva sekundarne arome pronađeni su u rakijama od sorti crnog grožda Teran i Cabernet Sauvignon, ali je utvrđeno da njihovi udjeli prvenstveno ovise o kvaliteti grožda i načinu pripreme komine. Rakije komovice od sorti Muškat bijeli i Muškat ruža porečki karakterizirala je izražena primarna, muškatna aroma, kao posljedica pojave visokih udjela monoterpena. Rakije komovice od sorte Malvazija istarska karakterizirali su izrazito visoki udjeli metanola. Utvrđeno je da povišeni udjeli masnih kiselina srednjeg lanca, a posebno njihovih etilnih estera te ostalih estera, mogu poslužiti kao pokazatelji bolje senzorske kvalitete, dok povišeni udjeli seskviterpena, diterpena, C6-alkohola, metanola, octene kiseline, masnih kiselina kratkog i dugog lanca te njihovih etilnih estera, acetatnih estera i aldehida, mogu poslužiti kao pokazatelji slabije senzorske kvalitete rakije komovice. Monovarietal grape marc distillates, produced by traditional distillation of marcs from the most important grape varieties in Istria, were characterized on the basis of volatile aroma compound composition. In produced distillates, as well as in different fractions of the distillates, the most important primary and secondary aroma compounds (terpenes, C13-norisoprenoids, methanol, higher alcohols, fatty acids, esters, aldehydes, ketones and acetals) were identified by gas chromatography-mass spectrometry (GC/MS), while their amounts were determined by gas chromatography with flame-ionization detector (GC/FID). The differences in volatile aroma compound composition between distillates made from different grape varieties were determined using statistical methods. The distillates were subjected to sensory evaluation by the DLG method, and correlations were determined between the amounts of aroma compounds and sensory quality. It was concluded that basic aroma of all investigated monovarietal grape marc distillates consists of the major secondary aroma compounds such as higher alcohols, volatile fatty acids, volatile esters and acetaldehyde, and in some cases, 1-hexanol. Distillates made from red grape varieties Teran and Cabernet Sauvignon contained higher amounts of the majority of secondary aroma compounds, but it was assumed that their amounts mostly depend on the quality of grapes and production parameters. Marc distillates made from Muscat blanc and Muscat rose of Porec grape varieties were characterized by pronounced primary muscat aroma, due to high amounts of monoterpenes. Malvazija istarska grape marc distillates were characterized by very high methanol content. It was determined that increased amounts of middle-chain fatty acids, and especially their ethyl esters, as well as other esters, could be used as indicators of higher sensory quality, while increased amounts of sesquiterpenes, diterpenes, C6-alcohols, methanol, acetic acid, short and long-chain fatty acids and their ethyl esters, acetates and aldehydes could be utilized as indicators of lower sensory quality of grape marc distillates.