Isolation and identification of txakoli yeasts from Bizkaia.

1998/11/01 Iriondo Gabilondo, Carmen Iturria: Elhuyar aldizkaria

• Kimika
• Ingurumena
• Unibertsitateak

The objective of the work is twofold: to identify and isolate fermentation yeasts and to help determine the chemical characteristics of Bizkaia txakoli. For this purpose, the volatile components and their evolution in the process will be analyzed. Yeasts may be selected based on their fermentation characteristics.

At Zalla Station, samples of a single variety of grapes will be taken from the adult grape, the must before and after the sulfitate, the turbulent fermentation and the end of fermentation. Volatile components will be determined by gas chromatography. In the arrival of the grapes and in the usual process of making txakoli, the corresponding yeasts will be taxonomically isolated and identified, at least, in 1996 and 1997. Oenological evaluation of Sacharomyces cervisae strains.

Background and current situation

Txakoli is a wine from Euskal Herria that has more and more social and economic importance. The methods of making txakoli and its chemical components have been little analyzed to date.

The Designation of Origin Bizkaiko Txakolina was obtained in 1994 (BOPV 94-VI-14) and for this purpose a study and report of enological parameters was carried out. The project, currently funded by the UPV/EHU, aims "The determination of the main volatile components".

In the txakoli industry there are many systems and techniques, but many are inadequate or obsolete. However, the quality of txakoli depends mainly on the quality of the initial must, the technological conditions of the winery and the participating yeast strains. Grape varieties, edafolophy and climate are related to the composition of the must. Yeast strains adapted to these ecological conditions are also developed. Isolating these natural strains and using them to ferment our musts is an opportunity to avoid the uniformization of wines.

Selected fermenting yeasts and Active Dry Yeasts (L.L.A.) are currently used are called. However, these commercial yeasts have been obtained far from the territory of our Denomination of Origin, which makes the production of wine in the molt today too homogeneous.

Objectives

The main objective of this study is the analysis and selection of txakoli yeasts and their relationship with aromatic composition through the analysis of volatile components.

The work objectives are:

• Isolation and identification of txakoli yeasts.
• Study of the evolution of the main organic components of the samples of a single grape variety in fermentation.
• Selection of native yeasts and offering to txakolineros.
• Systematically analyze the volatile substances of the Txakoli of Bizkaia.
• Sensory analysis by tasting txakoli.

• Project title: Isolation and identification of txakoli yeasts from Bizkaia and analysis of their influence on the aromatic composition
  of samples of a single grape variety.
• Project objective: Analysis and
  selection of txakoli hardware stores and study their relationship in aromatic composition by analyzing volatile components.
• Director: Carmen Iriondo.
• Working team: Two Research Groups of the Faculty of Sciences of the UPV/EHU (one from the Department of Organic Chemistry and another from the Department of Immunology, Microbiology and Parasitology), the Zalla Fruit Season of the Provincial Council of Bizkaia, the Regulatory Council of the D.O. "Bizkaiko Txakolina" and
  a private company dedicated to txakoli.