Selection of Indigenous Saccharomyces cerevisiae Strains from Kutjevo Wine Growing Area at the Laboratoy Scale

The use of selected yeasts for winemaking has clear advantages over traditional spontaneous fermentation. Selection of wine yeasts is usually carried out within the Saccharomyces cerevisiae species. Yeast strains produce different amount of secondary compounds that impart specific characteristics to the wines. This suggests that it is necessary to isolate naturally occuring autochthone strains, which exhibit a metabolic profile that corresponds to each wine. Twenty two strains of S.cerevisiae, isolated from the Kutjevo region (Gornji and Donji Hrnjevec, Mitrovac), Graševina grapes, were tested for: fermentation vigor, ethanol resistance, volatile acidity, H2S production and β-glucosidase, polygalacturonase, and killer activity. From the results of this investigation we are able to select two yeast strains (RO 1272 and RO 1284) for more detailed fermentation trials and possible use as a starter culture in production of typical wines

Usporedba aromatskih komponenti vina dobivenih fermentacijom Saccharomyces paradoxus i Saccharomyces cerevisiae sojeva

The aim of this study is to determine specific enological characteristics of Saccharomyces paradoxus species, potential differences in production of volatile components between Saccharomyces paradoxus and Saccharomyces cerevisiae strains and their influence on final wine quality. Samples of young wine were analysed for higher alcohols, fatty acids and volatile esters. At the same time wines were subjected to sensory evaluation. The results showed a notable influence of Saccharomyces paradoxus strain RO88 on chemical and sensory properties of Gewürtztraminer wine and indicated some differences between Saccharomyces paradoxus and Saccharomyces cerevisiae species.Cilj je ovog istraživanja utvrditi specifične enološke značajke vrste Saccharomyces paradoxus, potencijalne različitosti između vrste Saccharomyces paradoxus i Saccharomyces cerevisiae u sintezi hlapljivih komponenti te njihov utjecaj na kakvoću vina. Analizirane su koncentracije viših alkohola, masnih kiselina i hlapljivih estera, a vina su i senzorno ocijenjena. Rezultati su pokazali bitan utjecaj soja Saccharomyces paradoxus RO88 na kemijski sastav i senzorna svojstva vina Traminac te su upozorili i na razlike izme|u vrsta Saccharomyces paradoxus i Saccharomyces cerevisiae

Reduction in Acidity by Chemical and Microbiological Methods and Their Effect on Moslavac Wine Quality

Changes in chemical composition and sensory properties caused by chemical and microbiological methods of deacidification in Moslavac (syn. Furmint) wines were investigated. Alcoholic fermentation of Moslavac musts was carried out with two different strains of the yeasts Saccharomyces paradoxus. There were no marked differences in chemical composition among the wines. Compared to the control microbiological deacidification of wines by Oenococcus oeni resulted in a complete decomposition of malic acid, total acidity decrease of 1.55 g/L and pH value increase of 0.14 units. There were no significant differences in volatile acidity, tartaric and citric acid concentrations between the control and malolactically fermented wine. Chemically deacidified wines contained similar total acidity but higher pH values than malolactically fermented wines. Compared to control wines, the tartaric acid concentration decrease of 2.13 g/L and the pH value increase of 0.5 units were determined. The sensory quality of Moslavac wines of high acidity was improved by the applification of deacidification methods. Chemically deacidified wines were assessed as the best whereas the quality of the control wines was judged inferior

UTJECAJ KONTOROLIRANE MALOLAKTIČNE FERMENTACIJE NA SASTAV HLAPIVIH SPOJEVA U VINIMA KRALJEVINE

The effect of malolactic fermentation (MLF) on the volatile composition of white wines made from autochtonous grape variety Kraljevina was studied by inoculation with selected lactic acid bacteria. At the end of malolactic fermentation, after the decomposition of the malic acid present in wine the non volatile compounds were analyzed by HPLC, while volatile compounds were analyzed by gas chromatography. All wines were also sensory analyzed. Results showed changes in acetaldehyde, some higher alcohols, ethyl esters, free and bound monoterpenes and some organic acids that contribute to enhance the sensory properties and quality of Kraljevina wines that underwent malolactic fermentation.Istraživan je utjecaj malolaktične fermentacije (MLF) na sastav hlapivih spojeva u vinima Kraljevine primjenom selekcioniranih mliječno kiselih bakterija. Malolaktična fermentacija te analiza nehlapivih spojeva provedena je na HPLC-u dok su hlapive komponente analizirane pomoću plinske kromatografi je. Sva vina također su i senzorno ocijenjena. Rezultati su pokazali promjene u koncentracijama acetaldehida, nekih viših alkohola, etil estera, slobodnih i vezanih monoterpena te pojedinih organskih kiselina što je pridonijelo poboljšanju senzornih svojstava i kvalitete vina Kraljevina u kojima je provedena malolaktična fermentacija

THE EFFECT OF PARTIAL DEFOLIATION ON MONOTERPENE LEVELS OF GEWURZTRAMINER WINE (Vitis vinifera L.)

Poznato je da agrotehnički i ampelotehnički zahvati mogu značajno utjecati na kvalitativni sastav grožđa, mošta i vina. U cilju istraživanja utjecaja djelomične defolijacije, tijekom dvije godine praćen je sadržaj aromatskih komponenti u vinu Traminca mirisavog, Zagrebačkoga vinogorja, podregije Prigorje-Bilogora. Djelomična defolijacija u vidu odstranjivanja četiri (D1) i osam (D2) bazalnih listova obavljena je ručno u trenutku šare grožđa, dok su trsovi bez defolijacije poslužili kao kontrola. Uzorci za analizu uzimani su nakon provedenoga filtriranja, stabilizacije i buteljiranja vina. Pokazalo se da je sadržaj slobodno hlapivih (SHT), kao i potencijalno hlapivih terpena (PHT), u obje godine istraživanja bio najveći u vinu D2 varijante defolijacije, dakle u vinu dobivenom od suncu potpuno izloženih grozdova.It is well known that different viticultural practices have an important influence on the quality of grapes, must and wine. Aiming to examine impact of partial defoliation we were measured composition of the aromatic components in the wine of Gewurztraminer, winegrowing hills of Zagreb, subregion Prigorje-Bilogora. Partial defoliation, i.e. removing of 4 (D1) and 8 (D2) basal leaves, conducted manually at veraison and grapevines without defoliation (ND-non defoliated) were used as control. Samples for analyses were taken after filtration, stabilization and bottling of wine. It was shown that the wine made from completely sun exposed grapes (D2), were the richest in the content of free volatile terpenes (FVT) and potentially volatile terpenes (PVT) respectively

Influence of Indigenous Saccharomyces cerevisiae Strains on Higher Alcohol Content in Malvazija Istarska Wines

Istria is one of the most remarkable wine growing regions in Croatia. The main white grape variety is Malvasia from Istria (Malvazija istarska). Commercial yeast inocula, generally Saccharomyces cerevisiae, are widely used as starters today, however it might be preferable to use selected indigenous strains, which may have optimum abilities and may be better adapted to ferment the must of each area. Production and final concentration of higher alcohols is one of the strains most important oenological properties. In this research we extensively studied three indigenous S. cerevisiae strains during three years, isolated from the Istra wine region. Content of higher alcohols (1-propanol, 1-hexanol, Isobutanol, 1-butanol, Isoamyl alcohol and 2-phenyl ethanol were analyzed using GC-SHS. Compared to the control strain all tested indigenous yeast strains produced significantly lower concentration of 1 propanol while only the strain RO 1203 produced higher concentration of Hexanol, Isobutanol and 2-phenyl ethanol in all investigated years. In the 2000 and 2001. wines produced with strain RO1172 had the lowest total higher alcohol amount while in the year 2002 there were no difference between tested strains. Sensory evaluation carried out by Buxbaum method pointed out good enological properties and positive influence on final wine quality of all three tested S. cerevisae indigenous strains

Zmajevo oko – a unique example of anchialine system on the Adriatic coast (Croatia) during spring-summer stratification and autumn mixing period

Zmajevo oko is a naturally eutrophicated saline lake situated on the Gradina Peninsula, close to the village of Rogoznica on the central Dalmatian coast. Since 1992 the Lake has been intensively studied and in 2011 hydrographic and water column stratification in relation with reduced sulfur species and microbial activity was investigated during two different seasons: the spring-summer stratification and autumn mixing period