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Renner W.,Landwirtschaftliches Versuchszentrum Steiermark | Leitner E.,University of Graz | Eder R.,Lehr und Forschungszentrum fur Wein und Obstbau
Mitteilungen Klosterneuburg | Year: 2011

In the year 2009 three different variants of canopy management in the grape zone were investigated in a vineyard of the Landwirtschaftliche Versuchszentrum Steiermark in Southern Styria: untreated control (variant 1), single defoliation immediately after end of flowering (variant 2 - "half shade"), permanent defoliation from end of flowering onwards (variant 3). Furthermore, all different variants were harvested at three different dates each (early: 17 °KMW, medium: 19 °KMW, late: 20 °KMW). The parameters examined were the quality of grapes, yield data, and quality determining contents and aroma substances of the berries and the berry juice, respectively. All experimental variants were microvinified identically and the wines subjected to a descriptive assessment. In the untreated control an increased proportion of rot could be observed with the late harvest date. Yield per vine always was higher by trend with the untreated variant. The berries from variant 2 and 3 showed higher yellow colour values in the skin, but the concentration of 2-isobutyl-3-methoxypyrazine (IBMP) was lower. With increasing maturity the IBMP content also decreased. The amount of free assimilable nitrogen generally increased with increasing berry ripening, but in particular the content in variant 3 was lower by up to 13 %. The total of free and bound monoterpenes increased with the degree of ripeness, better exposed variants showing significantly higher (up to 50 %) concentrations. The sensory evaluation resulted in a preference for variant 3 with the early harvest date, the late harvest date wines of the untreated control variant were described as more intense, richer in fragrances and more full-bodied and they were preferred to the others. From the medium harvest date wines those from grapes of variant 2 ("half shade") were preferred. Harvest date and canopy management in the grape zone have a significant impact on the quality and contents of the berries and consequently on the wine style. From the results available to date from the year 2009 it can be concluded that with regard to aromatic development the intervention in the grape zone (defoliation) may be more severe, the sooner the harvest will take place. In further analytical and olfactory studies, the aging potential of these wines will be observed. Source

Experiments were carried out with red and white wines, which were treated with fining agents containing albumin or casein. Some protein residues of egg were detected in fined wines, depending on the concentration of the fining agent and time of storage. With the casein-fined wines no residues were found at all. It is possible to quantify egg white proteins and casein in wine using ELISA-tests. Furthermore these methods are suited for rapid analysis of samples in plenty supply and are thus the method of choice after the implementation of compulsory allergen labeling. Source

Michlmayr H.,University of Natural Resources and Life Sciences, Vienna | Eder R.,Lehr und Forschungszentrum fur Wein und Obstbau | Kulbe K.D.,University of Natural Resources and Life Sciences, Vienna | Del Hierro A.,Lehr und Forschungszentrum fur Wein und Obstbau
Mitteilungen Klosterneuburg | Year: 2012

The lactic acid bacterium Oenococcus oeni is the most important species for the controlled malolactic fermentation (MLF) of wine and it is best known for its generally positive effect on the wine fl avor. While the major impact of MLF is the reduction of acidity, the diverse metabolic side activities of O. oeni can exert significant infl uences on a wine's aroma profile. Of particular interest are glycosidase activities that catalyze the release of grape-derived aroma compounds such as terpenes. Many detailed studies conducted over the last decade revealed that O. oeni displays several glycosidase (glucosidase, xylosidase, arabinosidase and rhamnosidase) activities and that these activities indeed affect the complex wine aroma. Biochemical characterization of purified glycosidases from O. oeni led to vital insights into the mechanisms that can be made responsible, and gave further indications that could be helpful to explain the high strain-dependant variations on the molecular level. At present, O. oeni is probably one of the best studied organisms regarding its glycoside metabolism. Beyond its direct impact on wine making, this information is highly important to understand the β-glycoside metabolism of LAB in general, as orthologues to the glycosidase genes from O. oeni can be found in several other LAB species. Source

Navojska J.,Slovak University of Agriculture | Wendelin S.,Lehr und Forschungszentrum fur Wein und Obstbau | Eder R.,Lehr und Forschungszentrum fur Wein und Obstbau | Francakova H.,Slovak University of Agriculture
Mitteilungen Klosterneuburg | Year: 2012

This study deals with the determination of the origin of oenological tannins using the modifified OIV procedure. The method is based on HPLC analyses of proanthocyanidin contents (catechin, epicatechin, epigallocatechin, epicatechin- 3-O-gallate and epigallocatechin-3-O-gallate) after thiolytic cleavage of the flavonol intermonomer linkages in proanthocyanidins under heat in an acid medium (thioacidolysis). The purpose of the study was to differentiate oenological tannins gained from quebracho bark and tannins extracted from oak wood. As the results show, both groups of tannins do not produce any flavan-3-ols after thioacidolysis, but they show specific peaks, which enable determination of their origin. Source

Tiefenbrunner W.,Bundesamt fur Weinbau | Gangl H.,Bundesamt fur Weinbau | Leitner G.,Bundesamt fur Weinbau | Riedle-Bauer M.,Lehr und Forschungszentrum fur Wein und Obstbau | Tiefenbrunner A.,LMS Data
Mitteilungen Klosterneuburg | Year: 2011

In all Austrian winegrowing regions soil samples were taken from viticultural as well as agricultural areas and tested for nematodes of the family Longidoridae. In order to obtain a complete overview of the distribution of Longidoridae, samples were also taken from the riparian forests along the rivers Danube and March. Six species of the genus Xiphinema have been found in Austria up to now, but in vineyards only the following within the framework of this study: X. vuittenezi, the most present and abundant Longidoridae, and the X. americanum s. l. species X. brevicollum and X. pachtaicum. The latter is frequently found in vineyards north of the central Burgenland. The virus vectors X. index and X. diversicaudatum are rare according to current knowledge, although X. diversicaudatum is fairly abundant in common pastures and under fruit trees in Styria. Ten species of the genus Longidorus were found, two of which reached a high abundance in some samples: L. leptocephalus and L. raskii. The species L. elongatus, L. leptocephalus and L. poessneckensis are fairly widespread. Four species of this genus are vectors of various plant viruses: L. arthensis, L. attenuatus, L. elongatus and L. macrosoma. L. attenuatus transfers a grapevine virosis. From the genus Paralongidorus the species P. maximus, vector of a grapevine virus, has been found. Source

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