Utjecaj različitih načina provedbe jabučno-mliječne fermentacije na promjene kemijskih svojstava i hlapivih komponenti crnog vina Teran (Vitis vinifera L.)

Malolactic fermentation (MLF) is a complex biochemical process playing an important role in the production of red wines. The main reasons for its implementation are the reduction of titratable acidity and the consequent increase of pH, microbiological stability of wine, and changes in aromatic and sensory properties of wine. The aim of this study was to determine the compatibility of yeast and bacteria used by different malolactic fermentation techniques and their influence on the fermentation duration, concentration of individual organic acids, aroma compounds, and on chemical and sensory properties of Teran wines. The experiment included control treatment (without MLF), spontaneous MLF, induced MLF at the beginning of alcoholic fermentation with simultaneous inoculation of yeast and bacteria (coinoculation) and induced MLF after alcoholic fermentation (sequential MLF). In the co-inoculation treatment MLF had no negative effect on the alcoholic fermentation kinetic. Alcoholic fermentation was complete in all treatments. Coinoculation resulted in a significantly shorter duration of the MLF process. In all MLF treatments, significant reduction of titratable acidity and the increase of pH values was noted. Wines of the spontaneous MLF treatment obtained the highest concentration of volatile acidity and ethyl acetate. In all MLF treatments a complete consumption of malic acid and a decrease in concentration of citric acid, total amount of higher alcohols, and acetaldehyde were observed. Furthermore, significantly higher concentrations of ethyl esters, diacetyl, acetoin, and 2,3 butanediol were present in wines from all MLF treatments.Jabučno-mliječna fermentacija (JMF) složen je biokemijski proces koji ima važnu ulogu u proizvodnji većine crnih vina. Glavni učinci primjene JMF su snižavanje ukupne kiselosti uz rast pH vrijednosti, mikrobiološka stabilnost vina te promjena aromatskih senzornih svojstava vina. Cilj ovog istraživanja bio je utvrditi utjecaj različitih načina jabučnomliječne fermentacije na kompatibilnost kvasca i bakterija, duljinu trajanja fermentacije, koncentraciju pojedinačnih organskih kiselina i spojeva arome te senzorna svojstva vina sorte ´Teran´ (Vitis vinifera L.). Pokus je obuhvaćao kontrolni tretman (bez JMF), spontanu JMF, induciranu JMF u početku alkoholne fermentacije (koinokulacija) te induciranu JMF po završenoj alkoholnoj fermentaciji. U svim tretmanima alkoholna fermentacija je u potpunosti završila, bez zastoja ili usporavanja. Koinokulacija je utjecala na značajno kraće trajanje JMF. Svi tretmani s JMF značajno su utjecali na sniženje koncentracije titracijske kiselosti i povećanje pH vrijednosti. Najviše koncentracije hlapive kiselosti i etil acetata utvrđene su u vinima spontane JMF. U svim tretmanima s JMF zabilježena je potpuna razgradnja jabučne kiseline te sniženje koncentracije limunske kiseline, ukupnih viših alkohola i acetaldehida. Nadalje, značajno više koncentracije etilnih estera, diacetila, acetoina i 2,3-butandiola zabilježene su u svim tretmanima s JMF

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

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 length of maturation as a sparkling wine quality factor

Senzorna svojstva vina, kako mirnih tako i pjenušavih, definiraju se njihovim vanjskim izgledom, intenzitetom i čistoćom mirisa, harmoničnošću, čistoćom i punoćom okusa te općim dojmom koji proizlazi iz sveobuhvatnosti navedenih parametara. Proizvodnja pjenušavih vina klasičnom metodom podrazumijeva provođenje sekundarne fermentacije u boci što omogućava kontakt vina s talogom kvasaca određeni vremenski period čime se direktno utječe na aromatski profil i kakvoću okusa. Obzirom na sorpcijski kapacitet stanične stjenke kvasca, tijekom dozrijevanja može doći do značajnih razlika u koncentracijama pojedinih hlapivih spojeva, a samim time i intenziteta te kakvoće mirisa pojedinog pjenušca. U definiranju kakvoće pjenušavih vina, uz mirisna i okusna svojstva, vrednovanje vanjskog izgleda ima posebnu važnost obzirom na perlanje kao čimbenik koji ga razlikuje od mirnih vina, a čini i značajnu razliku među pojedinim pjenušcima. Cilj ovog istraživanja bio je utvrditi razlike u vanjskom izgledu, intenzitetu, duljini i kakvoći perlanja, kakvoći i postojanosti mirisa i okusa te općem dojmu kod 10 bijelih i 5 rosé pjenušavih vina različite duljine dozrijevanja.The sensory properties of still and sparkling wines are defined by their appearance, intensity and purity of smell, harmony, purity and fullness of taste, and the general impression derived from these parameters. The production of sparkling wines by classical method implies the implementation of secondary fermentation in the bottle, which allows the contact of the wine with yeast lees for a longer period of time, enabling direct effect on the aromatic profile and the taste quality of the end product. During maturation due to the sorption capacity of the cell wall of the yeast, significant differences can be found in the concentrations of the individual volatile compounds and hence the intensity and quality of the scent of each sparkling wine. In addition to the aromatic and taste properties, the evaluation of the external appearance in the definition of the quality in the sparkling wines is of additional importance and can vary greatly from sparkling wine to sparkling wine. Therefore, the aim of this study was to determine the differences in the intensity, length and quality of the foam and the external appearance, the aromatic profile, the quality and the persistence of taste and the general impression among the 5 rosés and 10 white sparkling wines with regard to the different length of maturation

CHANGES IN VOLATILE COMPOSITION OF KRALJEVINA WINES BY CONTROLLED MALOLACTIC FERMENTATION

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

The Effect of Bentonite Agents on the Aroma Composition of Sauvignon Blanc Wines

Bentonite fining is commonly used by the wine industry as a clarifying technique to remove proteins that are a potential source of haze in wines. Large amounts of added bentonite can decrease the sensory properties of wines. The aim of this research was to study the influence of the standard wine clarification process by two different types of bentonite fining agents on the basic chemical composition and aromatic profile of Sauvignon Blanc by gas chromatography-mass spectrometry (GC-MS). The general characteristic of Sauvignon Blanc wines showed no differences among treated wines independently of the type (sodium bentonite Bentogran® and sodium-activated bentonite Majorbenton C®) and the dose of bentonite. The results showed that type of bentonite regardless of the dose applied, affected the monoterpenes concentration