Utjecaj bistrenja bentonitom tijekom alkoholne fermentacije na proteinsku stabilnost, arome, fenole i senzorsku kvalitetu vina Malvazije Istarske

doctoral thesis

• Title (english): Influence of bentonite fining during alcoholic fermentation on protein stability, aromas, phenols, and sensory quality of Malvazija Istarska Wine
• Author: Ivana Horvat
• Mentor: Igor Lukić (mentor)
• Committee member: Mara Banović (predsjednik povjerenstva)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Technology and Analysis of Wine); Zagreb
• Defense date and country: 2020-10-27, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology
• Universal decimal classification (UDC): 663 - Industrial microbiology. Industrial mycology. Zymurgy, fermentation industry. Beverage industry. Stimulant industry

Abstract

Cilj ovog rada bio je istražiti utjecaj različitih uvjeta bistrenja bentonitom tijekom fermentacije - trenutka primjene, načina primjene i načina pripreme bentonita, primjene enoloških tanina u kombinaciji s bentonitom, temperature mošta tijekom bistrenja, primjene različitih doza bentonita te utjecaj tipa primijenjenog bentonita -na potrebnu dozu bentonita za postizanje proteinske stabilnosti vina, osnovne fizikalno-kemijske parametre kvalitete, hlapljive spojeve arome, fenole te senzorsku kvalitetu vina malvazije istarske. Najznačajnije smanjenje doze postignuto je primjenom bentonita u posljednjoj trećini trajanja fermentacije. Priprema bentonita u deioniziranoj vodi u manjoj je mjeri doprinijela sniženju doze. Primjena enoloških tanina snizila je ukupnu dozu potrebnog bentonita, ali u kombinaciji s bentonitom u fermentaciji nije postigla sinergijski učinak. Bistrenje bentonitom u fermentaciji značajno je utjecalo na fizikalno-kemijski sastav proizvedenih vina: očuvane su više koncentracije hidroksicinamoiltartarata, a posebno je značajan bio pozitivan učinak na očuvanje koncentracija ključnih hlapljivih spojeva fermentacijske arome, hlapljivih masnih kiselina i estera. Primjena tanina doprinijela je očuvanju viših koncentracija ukupne kiselosti, ukupnih fenola i hidroksicinamoiltartarata. Dodatak tanina, viša temperatura bistrenja te primjena više doze bentonita u fermentaciji imali su dodatan povoljan utjecaj na hlapljive estere. Pojedini tipovi bentonita pokazali su značajnije pozitivne učinke od ostalih. Bistrenje bentonitom tijekom alkoholne fermentacije pokazalo je jasan pozitivan učinak na senzorsku kvalitetu vina. Različiti pozitivni učinci bili su izraženiji u djelomično bistrenim vinima nakon fermentacije, dok ih je dodatno bistrenje nakon fermentacije umanjilo ili poništilo. Učinci pojedinih tretmana nisu bili jednakog intenziteta ili čak predznaka u različitim godinama istraživanjima. Daljnja istraživanja trebala bi se usredotočiti na utvrđivanje mogućnosti ograničenja nepovoljnih učinaka završnog bistrenja bentonitom nakon fermentacije, odnosno razjašnjavanje utjecaja fizikalno-kemijskog sastava grožđa kao polazišne sirovine na učinkovitost bistrenja tijekom fermentacije.

Abstract (english)

The aim of this study was to investigate the influence of different conditions of bentonite fining during fermentation - the moment of bentonite application, application method, bentonite preparation method, application of oenological tannins in combination with bentonite, must temperature during fining, bentonite dose, and bentonite type applied - on the required dose of bentonite to achieve protein stability, standard physico-chemical quality parameters, the concentrations of phenols and volatile aroma compounds, and sensory quality of Istrian Malvasia wine. The most significant reduction of dose was achieved by applying bentonite in the last third of the fermentation period. The preparation of bentonite in deionized water slightly contributed to the reduction. The application of oenological tannins lowered the total dose of bentonite required, but the combination of tannins with bentonite in fermentation did not achieve a synergistic effect. Bentonite fining during fermentation significantly affected physico-chemical composition of the produced wines: it preserved higher concentrations of hydroxycinnamyltartrates, while a positive effect on the preservation of the amounts of key fermentation aroma volatile compounds, such as volatile fatty acids and esters, was particularly significant. The application of tannins contributed to the preservation of higher concentrations of total acidity, total phenols, and hydroxycinnamoyltartrates. The addition of tannins, higher temperature during fining, and the application of higher dose of bentonite in fermentation had an additional beneficial effect on volatile esters. Particular types of bentonite showed more significant positive effects than others. Bentonite fining during alcoholic fermentation showed a clear positive effect on the sensory quality of the investigated wines. Various positive effects were more pronounced in partially fined wines after fermentation, while additional fining after fermentation reduced or nullified them. The effects of particular treatments were not of equal intensity or even sign in different years of research. Further research should focus on identifying the possibilities to limit the adverse effects of final fining with bentonite after fermentation, as well as on elucidating the influence of physico-chemical composition of grapes as raw material on the efficiency of fining during fermentation.

• Keywords: aroma; bentonit; bistrenje; fenoli; fermentacija; malvazija istarska; proteinska stabilnost; senzorska kvaliteta; vino
• Keywords (english): aroma; bentonite; fermentation; fining; Istrian Malvasia; phenols; protein stability; sensory quality; wine
• Language: croatian
• URN:NBN: urn:nbn:hr:159:733061
• Study programme: Title: Postgraduate PhD Study in Food Technology; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje biotehničkih znanosti, polje prehrambena tehnologija (doktor/doktorica znanosti, područje biotehničkih znanosti, polje prehrambena tehnologija)
• Type of resource: Text
• Extent: 227 str. : 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-02-18 11:56:30