Gene Technology in Winemaking: New Approaches to an Ancient Art

For the last century, the availability of pure culture yeast has improved reproducibility in wine fermentations and product quality. However, there is not a single wine yeast strain that possesses an ideal combination of oenological characteristics that are optimised for the task set by today´s leading winemakers. With new developments in modern winemaking there has arisen an urgent need to modify wine yeast strains in order to take full advantage of technology and to satisfy the demands of the sophisticated wine consumers. The combined use of mutagenesis, hybridisation and recombinant DNA methods have significantly increased the genetic diversity that can be introduced into Saccharomyces cerevisiae strains. The overall aim of the strain development programmes extends far beyond the primary role of wine yeast to catalyse the rapid and complete conversion of grape sugars into alcohol and carbon dioxide without distorting the flavour of the final product. Starter cultures of S. cerevisiae must now possess a range of other properties that differ with the type and style of wine to be made and the technical requirements of the winery. Our strain development programme focuses on a number of targets that are amenable to a genetic approach, including strain security and quality control, the increase of fermentation and processing efficiencies, and the enhancement of the sensorial quality and health properties of wine and other grape-based beverages. However, successful commercialisation of transgenic wine yeasts will depend on a multitude of scientific, technical, economic, marketing, safety, regulatory, legal and ethical issues. Therefore, it would be foolish to entertain unrealistic expectations over rapid commercialisation and short-term benefits. However, it will be equally unwise to deny the potential advantages of genetically improved wine yeasts to both the winemaker and consumer in the third millennium