Utjecaj ultrazvuka na inaktivaciju kvasca Brettanomyces u vinu

undergraduate thesis

• Title (english): The influence of ultrasound on inactivation of brettanomyces yeast in wine
• Author: Ema Stažić
• Mentor: Leo Gracin (mentor)
• 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: 2017-09-19, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Od samih početaka proizvodnje vina prisutno je smanjenje kvalitete i kvarenje vina. U današnjem vinarstvu najznačajniji uzročnik kvarenja crnih vina je vrsta kvasca Brettanomyces bruxellensis. Ekonomska šteta koju prouzrokuje navedeni rod mjeri se u milijunima američkih dolara. Brettanomyces spp. razvija se vrlo sporo i teško je uočiti da je vino inficirano. Brettanomyces vrste mogu sintetizirati hlapive fenolne spojeve kao što su 4-etilfenol i 4-etilgvajakol koji vinu daje prepoznatljivi “brett” miris što djeluje negativno na vino. U ovom radu ispitivan je utjecaj ultrazvuka visoke snage u kombinaciji sa povišenom temperaturom (termosonifikacija), a tretman je proveden u trajanju od 1,2 i 3 minute uz održavanje temperature od 43 °C. Učinak inaktivacije kvasca određen je praćenjem rasta kolonija kvasca B. bruxellensis na selektivnim podlogama. Senzorske promjene vina praćene su Triangl testom. Tretman ultrazvukom visoke snage u kombinaciji sa povišenom temperaturom uzrokuje djelomičnu inaktivaciju kvasca B. bruxellensis u vinu s 14 vol. % alkohola pri čemu ne utječe na senzorske karakteristike vina. Različiti pH u vinu s 14 vol % alkohola nema utjecaja na inaktivaciju kvasca B. bruxellensis dok prisutnost šećera u vinu s 14 vol % alkohola utječe na smanjenje inaktivacije ovog kvasca kod pH 3,7 i 3,9.

Abstract (english)

In present-day enology the most significant cause of wine spoilage is Brettanomyces bruxellensis yeast. The economical damage caused by the above-mentioned yeast is valuated in millions of US dollars. Brettanomyces bruxellensis yeast develops very slowly and there are no visible signs that the wine is infected. It can synthesize volatile phenolic compounds like 4- ethyl phenol and 4-ethyl guaicaol, which give wine recognizable “brett” flavor which has a negative on wine. In this work, the influence of high power ultrasound in combination with high temperature was examined. Ultrasound was applied in durations of 1,2 and 3 minutes while the samples were preheated at 43°C. Inactivation of yeast was monitored by inoculation of wine samples on a selective medium. Sensory characteristics of wine were determined using the Triangle test. High power ultrasound combined with high temperature (termosonification) caused partial inactivation of B. bruxellensis yeast in wine with 14 vol. % alcohol without affecting its sensory characteristics. Variation in the pH in wine has no effect on inactivation of Brettanomyces yeast. The addition of sugar in wine caused lower inactivation of Brettanomyces yeast at pH 3,7 and 3,9 of wine.

• Keywords: kvasac Brettanomyces bruxellensis; termosonifikacija; kvarenje vina; inaktivacija kvasca
• Keywords (english): Brettanomyces bruxellensis yeast; termosonification; wine spiolage; yeast inactivation
• Language: croatian
• URN:NBN: urn:nbn:hr:159:824400
• Study programme: Title: Food Technology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka prehrambene tehnologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka prehrambene tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-09-20 09:42:17