Effect of accelerated autolysis of yeast on the composition and foaming properties of sparkling wines elaborated by a champenoise method.

Five mutants (obtained by UV mutagenesis) and the parent strain were selected to produce sparkling wines following the traditional or champenoise method. The wines were aged with the yeast for 9 months, with samples being taken each month for analytical and sensory determinations. The wines elaborated with mutant strain IFI473I demonstrated an accelerated release of protein, amino acids, and polysaccharides. An analysis of the secreted polysaccharides revealed that mannose was the major sugar present. The effects of the products released by yeasts on the foaming properties of the wines were determined by both sensory and instrumental analysis. In all cases, the wines elaborated with mutant strain IFI473I showed improved foaming properties as compared to wines fermented without this strain. Similar results were obtained at a decreased aging time of 6 months, thereby confirming the capacity of IFI473I strain to carry out an accelerated autolysis. These results demonstrate that mutant strain IFI473I can significantly reduce production times of high-quality sparkling wines.

Application of a DNA analysis method for the cultivar identification of grape musts and experimental and commercial wines of Vitis vinifera L. using microsatellite markers.

A DNA-based method has been applied to the identification of several musts and wines using microsatellite markers. DNA was extracted from the solid phases of sixteen monovarietal and five multivarietal musts (mixtures of two musts down to a 4:1 proportion) and they were genotyped at seven microsatellites through a multiplex PCR reaction and automated fluorescent detection. PCR multiplexing was successful in monovarietal musts, but should be used with caution with at least some markers and in multivarietal musts. The same extraction and detection methods were unsuccessfully applied to the solid and liquid phases of five monovarietal commercial wines, even after using different concentration procedures. Nucleic acids presence was then studied in a recent must, during the fermentation process, and during the subsequent steps of winemaking. Genotyping was possible in the resulting experimental wine until decanting, when the particles in suspension were removed. These results suggest that wine authentication through DNA analysis is not possible in commercial wines, in the tested conditions.