Primjena lakaze i ultrafiltracije u sprječavanju posmeđivanja bijelih vina

doctoral thesis

• Title (english): Ultrafiltration and laccase application in prevention of white wine browning
• Author: Zrinka Čosić
• Mentor: Mara Banović (mentor)
• Committee member: Branka Levaj (predsjednik povjerenstva)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; Zagreb
• Defense date and country: 2012-07-23, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology
• Universal decimal classification (UDC): 633/635 - Horticulture. Fruit growing. Viticulture. Gardening

Abstract

Posmeđivanje bijelih vina je jedna od najnepoželjnijih pojava u proizvodnji bijelih vina. Ono je rezultat vrlo složenih reakcija niskomolekularnih fenolnih spojeva pri čemu nastaju visokomolekularni kompleksi koji su netopljivi i razlog su zamućenja vina. Kako bi se taj problem prevladao u praksi se primjenjuje više različitih postupaka. Jedan od načina je i primjena enzima lakaze u kombinaciji s membranskom separacijom, ultrafiltracijom. Lakaza je enzim koji upravo katalizira oksidaciju niskomolekularnih fenolnih spojeva u visokomolekularne kondenzirane produkte koje je tada moguće ukloniti iz supstrata ultrafiltracijom. Tim postupkom uklone se niskomolekularni fenolni spojevi i vino ne bi trebalo više biti podložno posmeđivanju. Svrha ovog rada je bila ispitati efikasnost primjene lakaze u kombinaciji s ultrafiltracijom na moštu i vinu grožđa Laški rizling u odnosu na neka najčešće korištena sredstva za bistrenje. Nesumporeni mošt je podvrgnut fermentaciji s autohtonom i selekcioniranom kulturom kvasaca. Bistrenje je provedeno dodavanjem želatine/kiselsol, polivinilpolipirolidona i lakaze i to prije (u mošt) ili nakon završetka fermentacije (u vino). Sva proizvedena vina podvrgnuta su ultrafiltraciji. Uspješnost procesa bistrenja ispitana je i nakon dvije godine skladištenja svih uzoraka vina u uvjetima vinskog podruma. U uzorcima mošta i vina određivani su slijedeći parametri: boja, ukupni fenoli, flavonoidni i neflavonoidni fenoli, kondenzirani tanini, leukoantocijani, ukupna aroma, maseni udio koloida i osnovni kemijski sastav. U radu su eksperimenti provedeni u laboratorijskom i industrijskom mjerilu. U svim slučajevima pokazalo se da lakaza uspješno smanjuje koncentraciju leukoantocijana i kondenziranih tanina, fenolnih spojeva odgovornih za posmeđivanje.

Abstract (english)

The browning of white wines is one of the most undesirable side effects in their production. Browning occurs as a cascade of the complex reactions of low-molecular-weight phenolic compounds into high-molecular-weight complexes insoluble in water (hence the cloudiness). There are several practices to alleviate this problem, one of them being mutual application of laccase and ultrafiltration (membrane separation method). Laccase is oxidative catalytic enzyme that condenses low-molecular-weight phenolic compounds into high-molecular-weight products, easily removable by ultrafiltration. Such process separates low-molecular-weight phenolic compounds from the wine and prevents browning. The purpose of this dissertation was to examine efficiency of mutual application of laccase and ultrafiltration on musts and white wine (sort Laški rizling) in comparison to the most commonly used fining agents. Non-sulphureted musts were fermented with native and selected yeasts. Tested fining agents were gelatin/kiselsol, polyvinylpolypyrrolidone and laccase added to must prior fermentation and added to wine after fermentation. Clarification success was evaluated after 2 years of storage under usual vine cellar conditions. All wines were filtered with ultrafiltration. Researched parameters for both, musts and wine were: color, total phenols, flavonoids, non-flavonoids, condensed tannins, leucoanthocyanins, total aroma, amount of colloids, and basic chemical composition. Experiments were done under laboratory and industrial conditions. Results showed that laccase in all cases decreased concentration of leucoanthocyanins, condensed tannins, and phenolic compounds responsible for browning of wines.

• Keywords: bijelo vino; bistrenje; lakaza; posmeđivanje vina; ultrafiltracija
• Keywords (english): fining; laccase; ultrafiltration; white wine; wine browning
• Language: croatian
• URN:NBN: urn:nbn:hr:159:059821
• Promotion: 2013-09-30
• 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
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2018-05-16 11:30:10