Optimal use of Hanseniaspora peculiarities in winemaking (intervento orale)

The genus Hanseniaspora includes apiculate yeasts that not only produce ethanol during fermentation, but also high amounts of acetic acid, which, although varying from strain to strain, prevent their use as single wine starters (Caridi et al., 1991). Several studies show that the unacceptably high volatile acid production by some Hanseniaspora species does not occur when these yeasts are grown in mixed culture with Saccharomyces cerevisiae (Fleet 2008). This research aims at verifying the possibility to employ selected strains of the genus Hanseniaspora as single wine starters valorizing their weak point - the high production of volatile acidity - to obtain citrus wine characterized by a very high content in flavored and volatile compounds, including acetic acid. Then the citrus wine may be oxidized by selected acetic acid bacteria to produce a much appreciated citrus vinegar (Caridi 2005). Twenty-nine Calabrian strains of Hanseniaspora sp. and 4 control strains of Saccharomyces cerevisiae were selected using two different juice combinations: A) mix of bergamot (Citrus bergamia Risso) juice and grape must from dried grapes [ratio 1:2] - pH 2.94, °brix 20.80, and B) bergamot juice with the addition of saccharose - pH 2.94, °brix 20.80. The juices were prepared and immediately inoculated in duplicate with the yeast strains. The fermentations were studied determining the weight loss caused by CO2 production. When the CO2 production finished the wines were analyzed. On the whole, the results demonstrate the possibility to employ selected strains of the genus Hanseniaspora as single starter culture in winemaking. The excellent results obtained may be further implemented by genetic improvement: since Hanseniaspora produces ascospores, this research will continue by segregation and breeding of the best selected strains.Caridi A. et al. - Oenological characteristics of Hanseniaspora guilliermondii. Vini d’Italia, 33, 51-57, 1991 (in Italian).Caridi A. - Fruit vinegars based on citrus wines. International Symposium on Vinegars and Acetic Acid Bacteria, Reggio Emilia (Italy), 8-12 May 2005.Fleet G.H. Wine yeasts for the future. FEMS Yeast Res, 8, 979-995, 2008.