Starmerella bacillaris (synonym Candida zemplinina) is an important non-Saccharomyces yeast in winemaking with valuable oenological properties, accompanying Saccharomyces species in sweet wine fermentation, and has also been suggested for application as combined starter culture in dry or sweet wines. In this study, the major metabolites and nitrogen utilization of these yeasts are evaluated in the musts with high or extremely high sugar concentration. The change in the metabolic footprint of Saccharomyces cerevisiae, Saccharomyces uvarum and Starmerella bacillaris strains was compared when they were present as pure cultures in chemically defined grape juice medium with 220 and 320 g/L of sugar, to represent a fully matured and an overripe grape. Surprisingly, the extreme sugar concentration did not result in a considerable change in the rate of sugar consumption; only a shift of the sugar consumption curves could be noticed for all species, especially for Starmerella bacillaris. At the extreme sugar concentration, Starmerella bacillaris showed excellent glycerol production, moderate nitrogen demand together with a noticeable proline utilisation. The change in the overall metabolite pattern of Starmerella bacillaris allowed clear discrimination from the change of the Saccharomyces species. In this experiment, the adequacy of this non-Saccharomyces yeast for co-fermentation in juices with high sugar concentration is highlighted. Moreover, the results suggest that Starmerella bacillaris has a more active adaptation mechanism to extremely high sugar concentration.
The aim of this study was to compare different Hungarian Kadarka, Kékfrankos, and Cabernet franc wines produced and aged by the same methods and to compare two types of sensory analysis methods as well: the 100‐point OIV system and quantitative descriptive analysis (QDA). Both tests were conducted by 12 assessors of the University of Pécs, Institute for Regional Development, Faculty of Horticulture and Oenology. This study provides conclusions about the use of sensory analysis methods, highlighting the advantages and disadvantages of QDA and the OIV system. Principal component analysis, analysis of variance (ANOVA), multiple factor analysis, and partial least squares dicriminant analysis were used for the evaluation of the data. Our results showed that the sensory panel was able to discriminate the samples by both sensory methods; however, the information provided by them was significantly different. ANOVA clearly showed that the two methods have different sensitivity when comparing wines (commercial and produced wine samples) and QDA proved to be the more sensitive, as well as more detailed, method. Partial least squares discriminant analysis augmented the findings in the classification part of the different type of wine samples. In general, OIV is able to show the general quality of the wines, while QDA coupled with proper chemometric methods is able to describe why the given samples received good or bad OIV scores.
Polyphenol compounds in grapes and wines are of paramount importance: they have a key role in determining wine quality, and also the benefi cial health effects of moderate red wine consumption are well-known. The polyphenol concentration of wines is determined mostly by: a) their concentration in the grapes and b) the production technology, particularly the time and type of aging. Our goal was to determine the trans-resveratrol and anthocyanin contents of Hungarian red wines under different manufacturing conditions, by monitoring the 24-month aging process-using barrique and oak barrels-with semi-annual sampling, without considering vintage. We have chosen to determine polyphenol components that could originate from either the grapes, or be produced during the wooden barrel aging. Both the aging time and the wine variety had non-negligible effects on the changes in the concentrations of the studied components, whereas the wooden barrel type had not.
The aim of this study was to find out what kind of “Bianca” wine could be produced when using organic yeast, what are the dynamics of the resulting alcoholic fermentation, and whether this method is suitable for industrial production as well. Due to the stricter rules and regulations, as well as the limited amount and selection of the permitted chemicals, resistant, also known as interspecific or innovative grape varieties, can be the ideal basic materials of alternative cultivation technologies. Well-designed analytical and organoleptic results have to provide the scientific background of resistant varieties, as these cultivars and their environmentally friendly cultivation techniques could be the raw materials of the future. The role of the yeast in wine production is crucial. We fermented wines from the “Bianca” juice samples three times where model chemical solutions were applied. In our research, we aimed to find out how organic yeast influenced the biogenic amine formation of three important compounds: histamine, tyramine, and serotonin. The main results of this study showed that all the problematic values (e.g., histamine) were under the critical limit (1 g/L), although the organic samples resulted in a significantly higher level than the control wines. The glycerin content correlated with the literature values, since it is well known that the glycerin-pyruvic acid transformation results in a 6–10 g/L concentration.
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