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Seven indigenous yeast strains of Saccharomyces paradoxus previously isolated and identified using molecular and physiological methods were tested for their fermentation abilities. Chemical analyses of produced wines showed differences compared with the Saccharomyces cerevisiae strain used as a control. The examined S. paradoxus strains showed good fermentation vigour, ethanol tolerance and difference in the fermentation rate. Four of seven analysed S. paradoxus strains (RO66, RO54, RO11 and RO134) metabolised sugar up to 1 g L-1. The total amount of higher alcohol was lower compared with S. cerevisiae wines. Strain RO83 was able to degrade up to 40% malic acid and can be used for biological deacidification. Sensory evaluation of dry and semidry wines underlined good enological properties and positive influence of tested wine strains on final wine quality. All these properties of S. paradoxus strains pointed out the possibility of their application in wine industry. © 2006 Institute of Food Science and Technology Trust Fund

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Commercial sparkling wine production represents a relatively low but important part of the Croatian wine production, especially in the Zagreb county. This study presents the results of volatile aroma compounds profile and organic acid composition of commercial sparkling wine samples from three vine-growing regions in Zagreb county. In total, 174 volatile aroma compounds were identified, separated between their chemical classes (aldehydes, higher alcohols, volatile phenols, terpenes, C13-norisoprenoids, lactones, esters, fatty acids, sulfur compounds, other compounds, other alcohols). Higher alcohols such as phenylethyl and isoamyl alcohol as well as 2-methyl-1-butanol, and esters such as diethyl succinate, ethyl hydrogensuccinate, and ethyl lactate had the strongest impact on the volatile compounds profile of Zagreb county sparkling wine. The presence of diethyl glutarate and diethyl malonate, compounds whose concentrations are influenced by yeast autolysis or caused by chemical esterification during the ageing process, was also noted. The influence of every single volatile aroma compound was evaluated by discriminant analysis using forward stepwise model. The volatile profiles of traditional sparkling wines from Croatia were presented for the first time. It is hoped the results will contribute to better understanding the quality potential and to evaluate possible differences on the bases of detected aroma concentrations and multivariate analysis.

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The aim of this research was to identify the Saccharomyces spp. associated with Ž ilavka grapes and to evaluate their enzymatic activities, H 2 S production and micro-fermentation performance. For this purpose, a total of 143 yeast strains isolated from three production areas of the Mostar wine region (Bosnia and Herzegovina) were studied and analysed. Firstly, yeasts were identified to genus level by growth on WL nutrient agar and the test of assimilation of lysine. Later, molecular identification at species level was carried out with RFLP analysis of 18S rDNA ? ITS region, and at strain level with microsatelliteprimed PCR (MSP-PCR). At physiological level yeast strains were grouped into different clusters by means of the Joining-Tree-Clustering-Method. All yeasts tested were identified as S. cerevisiae, resulting a total of 18 different strains. All of the investigated strains produced hydrogen sulphide, 89% were able to complete the fermentation, and none of them was able to synthesize killer toxins. Since enzymes play a very important role in wine aroma development, it was very encouraging that 33% of the strains were able to synthesize pectinolytic enzyme but only one produced b-glucosidase. In the second part of the selection process two indigenous strains were compared with commercial yeast in a microvinification and Ž ilavka wines with different profiles of volatiles were obtained. This research represents a first step in the selection of indigenous yeast strains from the Mostar region with the goal of maintaining the specific organoleptic characteristics of Ž ilavka wine.

Atypical aging off-flavour (UTA) is not a common wine fault but it is still an interesting topic, due to the complexity of the occurrence, chemical markers, and sensory descriptors. Although 2-aminoacetophenone (AAP) is the main chemical marker, an increase in AAP concentration does not necessarily result with the higher sensory expression of UTA. The goal of this study was to investigate the presence of UTA and the link between UTA olfactory perception and AAP concentration in Croatian wines. All the samples that were rejected due to the UTA in sensory testing during the certification procedure for the market during 2013 -2017 were included in research. The relevant data of origin were analyzed to filter out potential factors of UTA appearance. Sensory analyses were performed with the "100 points" and the "Yes/No" methods, and AAP analyses were done by GC-MS. The appearance of UTA may be associated with the regional origin and extremely poor climatic conditions of a particular year. The results of AAP analyses corroborated the presence of UTA in all samples; the concentrations of AAP were 0.3 -4.4 µg/L. A respective correlation between sensory recognition and the concentration of AAP was specified. This is the first study of sensory detection of UTA and the interconnection with 2-AAP in Croatian wines. The results indicate the need to detect as many volatiles as possible, to explain the difference in olfactory perception of this fault.