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Gewählte Master / Diploma Thesis:

Manuela Polinkiewicz (2013): Dynamik der Oenokokkenpopulation während der malolaktischen Fermentation hochalkoholischer Weine.
Master / Diploma Thesis - Institut für Lebensmittelwissenschaften, BOKU-Universität für Bodenkultur, pp 174. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
Malolactic fermentation (MLF) is a process performed by lactic acid bacteria (LAB) in wine, during which L-malic acid is converted to L-lactic acid and CO2, having positive effects on sensorial quality and biological stability. Especially Oenococcus oeni isolated from wines is used as starter culture. Unfortunately, LAB are inhibited by harsh environmental conditions during winemaking, like high ethanol- and SO2-concentrations or low pH and temperature. Several researchers have selected and evaluated strains of LAB, which are able to perform MLF under these conditions. Their results facilitated the development of starter cultures for wines with alcohol concentrations exceeding 15% (v/v). The aim of this study was performing MLF in a Viennese Chardonnay with 15.3% (v/v) ethanol and pH 3.46. Four high-alcohol tolerant starter cultures were inoculated either directly or after a 48h-acclimation in a 1:1 wine-water solution. Microbiologic analyses were done by counting colonies on BCM- and MRS-medium after seven days of anaerobic incubation at 30 °C. Subsequently isolates were cultured for molecular typing. Additionally, L-malic acid-depletion and lactic acid-production were measured using enzymatic determination methods. The results showed that two starter cultures, directly inoculated as well as acclimated, were able to grow after a lag phase, and thus performed MLF. The third starter culture was able to induce a delayed and stuck MLF when inoculated directly. The fourth starter did not succeed to adapt and start MLF in both cases. Comparing inoculated directly with acclimated starter cultures, there was some faster recovery of the directly inoculated starter cultures. The results of the L-malic acid- and lactic acid monitoring agreed with this observation. The findings lead to the conclusion that two of the four starters tested are suitable for this special type of wine. In addition, direct inoculation is preferable.

Beurteilende(r): Kneifel Wolfgang
1.Mitwirkender: Domig Konrad
2.Mitwirkender: Mayrhofer Sigrid

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