Since 2016, our winemaking R&D team has been part of a consortium, funded by the EU (FEDER) Compete 2020 Programme initiative, conducting a study into how specific natural yeast strains in wine fermentations can influence the aroma profile of port, specifically with the Touriga Nacional grape variety. 

Yeast is fundamental in winemaking as it is the catalyst for the fermentation of grape sugar into alcohol. Port’s intrinsic aroma characteristics are shaped by a series of factors including terroir particularities, grape varieties and winemaking procedures that include, among many other parameters, specific yeast strains.

Consistency in winemaking has led to the almost ubiquitous application of commercial Saccharomyces yeast strains. Although the recent introduction of commercial non-Saccharomyces strains has resulted in improved complexity, the potential impact and diversity of native Douro yeast strains responsible for port production have yet to be fully understood.

The work has involved the isolation, identification and characterization of non-Saccharomyces yeasts from spontaneous alcoholic fermentations. These so-called ‘wild yeasts’ were always important in port production, particularly in the first stages of fermentation. The objective is to identify and select the best yeasts to maximize quality complexity.

A total of 500 yeasts were isolated from 12 identified species and 4 of these had the most promising attributes for further evaluation. 16 strains from these 4 species were used in fermentations and the resulting wines showed very promising properties. The work has shown that indigenous Douro yeast strains have considerable winemaking potential and continue to be studied by our R&D team.