Impact of microbiological and technological factors on volatile phenols content in Montenegrin red wines

Radonjić, Sanja (author), Košmerl, Tatjana (mentor), Prosen, Helena (co-mentor)

The aim of this research has been to examine the microbiological and technological parameters influencing volatile phenols (VP) production in wine of the autochthonous Montenegrin grape varieties Kratošija and Vranac and the international grape variety Cabernet Sauvignon. Within two consecutive vintages (2012 and 2013) grape must and wines have been analysed on the presence of Dekkera bruxellensis yeast and on hydroxycinnamic acids (HCA) as precursors of VP. Among technological parameters, the influence of commercial yeast and lactic acid bacteria (LAB) and the addition of oak alternatives on wine chemical composition and sensory profile has been examined. Caffeic acid represented the prevalent HCA compound for all varietal wines, with the exception of Kratošija in the 2012 vintage in which ferulic acid (93.2%) was the main HCA. Higher total content of all three examined HCA was observed in all varietal wines inoculated with commercial yeast in 2012, as compared to 2013, due to the high content of caffeic acid in the 2012 vintage. Statistically significant differences in VP content were found between commercial yeast, LAB and oak alternatives. The presence of Dekkera bruxellensis spp. has been noticed only in the 2013 vintage for Vranac control wine after alcoholic fermentation (AF), confirming that these yeasts are present in extremely low numbers at the beginning of AF only. Vranac wines, inoculated with commercial yeast, contained the highest content of p-coumaric acid in 2012 (1.54 mg/L), followed by Kratošija wines in the 2013 vintage (1.03 mg/L). The highest number of samples with detected VP from the vintage 2012 were found for Vranac wines (12 out of 28), while in 2013 vintage, Kratošija had the highest number of samples (18 out of 28). VP have appeared only in wines of autochthonous grape varieties, after long bottle aging and the number of infected samples were vintage dependent. Comparing autochthonous Montenegrin wines to Cabernet Sauvignon, it can be concluded that this international variety grown in agro-ecological conditions of Ćemovsko field does not show increased VP even after three or four years of aging in bottles. It has been concluded that VP are formed predominantly in wines with high alcohol content, low pH, low reducing sugars content, and even in wines with free SO2 above 30 mg/L

• Language: English
• Keywords: wine, volatile phenols, hydroxycinnamic acids, starter cultures, yeasts, lactic acid bacteria, red wine, autochthonous grape varieties, Vranac, Kratošija, Cabernet Sauvignon
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [S. Radonjić]
• Year: 2020
• PID: 20.500.12556/RUL-124107
• UDC: 663.252:579.6:547.56:543.2(043)=111
• COBISS.SI-ID: 44956419
• Publication date in RUL: 31.12.2020

Secondary language

• Language: Slovenian
• Title: Vpliv mikrobioloških in tehnoloških dejavnikov na vsebnost hlapnih fenolov v črnogorskih rdečih vinih

Abstract

Cilj te raziskave je bil proučiti mikrobiološke in tehnološke parametre, ki vplivajo na tvorbo hlapnih fenolov (VP) v vinih avtohtonih črnogorskih sort vinske trte 'Kratošija' in 'Vranac' ter mednarodne sorte 'Cabernet Sauvignon'. V dveh zaporednih letnikih trgatve (2012 in 2013) so bili analizirani vzorci mošta in vina na prisotnost kvasovk vrste Dekkera bruxellensis in vsebnost hidroksicinametnih kislin (HCA) kot predhodnikov VP. Med tehnološkimi parametri smo proučili vpliv dodatka starterskih kultur komercialnih kvasovk in mlečnokislinskih bakterij (LAB) ter alternativ hrasta na kemijsko sestavo in senzorični profil vina. Kavna kislina je predstavljala prevladujočo HCA v vseh pridelanih sortnih vinih, z izjemo vina kratošija letnika 2012, kjer je bila glavna HCA ferulna kislina (93,2 %). V vseh sortnih vinih, pridelanih z inokulacijo s komercialnimi kvasovkami, smo v letniku 2012 opazili večjo skupno vsebnost vseh treh preiskovanih HCA v primerjavi z letnikom 2013, predvsem zaradi velike vsebnosti kavne kisline v letniku 2012. Ugotovljene so bile statistično značilne razlike v vsebnosti VP med komercialnimi kvasovkami, LAB in alternativami hrasta. Prisotnost kvasovk rodu Dekkera bruxellensis spp. je bila opažena šele v letniku 2013 za kontrolno vino vranac po zaključeni alkoholni fermentaciji (AF), kar potrjuje, da so te kvasovke prisotne v izjemno majhnem številu samo na začetku AF. Vina vranac, inokulirana s komercialnimi kvasovkami, so vsebovala največjo vsebnost p-kumarne kisline v letniku 2012 (1,54 mg/L), sledila pa so jim vina kratošija v letniku 2013 (1,03 mg/L). Največ vzorcev z odkritimi VP v vinih letnika 2012 je bilo ugotovljenih pri sorti vranac (12 od 28 vzorcev), medtem ko je bilo največ vzorcev v letniku 2013 pri sorti kratošiji (18 od 28 vzorcev). VP so se pojavili le v vinih avtohtonih sort grozdja po dolgem staranju stekleničenega vina, število okuženih vzorcev pa je bilo odvisno od letnika. Če primerjamo avtohtona črnogorska vina s sorto cabernet sauvignon lahko ugotovimo, da ta mednarodna sorta, pridelana v agroekoloških pogojih Ćemovskega polja, ne kaže povečanja VP tudi po treh ali štirih letih staranja v steklenicah. Ugotovljeno je bilo, da VP nastajajo pretežno v vinih z večjo vsebnostjo alkohola, nizkim pH, majhno vsebnostjo reducirajočih sladkorjev in celo v vinih s prostim SO2 nad 30 mg/L

• Keywords: vino, hlapni fenoli, hidroksicimetne kisline, starterske kulture, kvasovke, mlečnokislinske bakterije, rdeče vino, avtohtone sorte, vranac, kratošija, cabernet sauvignon