Effect of high intensity ultrasound on yeast of Brettanomyces genus and sensory quality of wine

Potencijalna upotreba ultrazvučnih valova za kontrolu mikroorganizama u vinu je neistražena. To onemogućava određivanje mogućnosti primjene ultrazvuka visokog intenziteta u tehnologiji vina. Kvasci roda Brettanomyces mogu se naći u svim vinarskim regijama svijeta, a jedni su od najvećih proizvođača hlapljivih fenola iz fenolnih kiselina prisutnih u grožđu koje vinu daju neugodan miris, poznat kao „Brett“ miris. Ovim radom želi se istražiti kako protočni ultrazvuk visoke snage pri frekvenciji 24 kHz ultrazvučnom sondom nominalne snage 400 W utječe na kvasce iz roda Brettanomyces i senzorsku kvalitetu vina. Pripremljeni uzorci vina tretirani su protočnim ultrazvukom. Fourier-ovom transformacijom infracrvene spektroskopije (FTIR) određivali su se parametri vina. Nacjepljivanjem uzoraka vina na selektivne podloge dokazano je da su kvasci roda Brettanomyces prisutni u vinu. Rezultatima ispitivanja utvređeno je da povišena temperatura i produljneo djelovanje ultrazvuka imaju negativan utjecaj na aromu vina. Utvrđeno je da se rezistentnost kvasaca roda Brettanomyces u vinu, smanjuje povečanjem temperature i produljenjem vremena tretmana ultrazvukom nominalne snage 400W i frekvencije 24 kHz.Potential use of ultrasonic waves for control of microorganisms in wine is unexplored. This prevents the possibility of determining the application of high intensity ultrasound in wine technology. Yeasts of Brettanomyces genus can be found in all wine regions of the world, and they are one of the largest producers of perspirant phenols from phenolic acids present in grape which give unpleasant smell (known as ''Brett'' smell) to wine. The aim of this thesis was to examine how high intensity ultrasound at a frequency of 24 kHz with an ultrasound probe of a nominal power of 400 W effects yeasts of Brettanomyces genus and sensory quality of wine. With the Fourier-transform infrared spectroscopy the parameters of wine were determined. Inoculation of samples of wine on selective media showed that the yeasts of Brettanomyces genus were present in wine. It was determined that higher temperatures and prolonged action of ultrasound have a negative impact on wine aroma. Also it was established that the resistance of yeasts of Brettanomyces genus decreases with increase of temperature and prolonged treatment time with ultrasound of nominal power of 400 W and frequency of 24 kHz