Research study: using wild Douro yeasts in Port production
“Porto Non-Saccharomyces – Selection of Indigenous Non-Saccharomyces Yeasts from Port Wine”
Since 2016, our winemaking R&D team has been part of a consortium (Symington - Ângelo Coimbra - Biocant), funded by the EU (FEDER) Compete 2020 Programme initiative, studying how indigenous non-saccharomyes yeast strains isolated from spontaneous wine fermentations can influence the aroma profile of port, specifically looking at the Touriga Nacional and Touriga Franca grape varieties.
Yeast is the fundamental catalyst in winemaking, producing alcohol from grape sugar, as well as innumerate volatile metabolites responsible for the complex bouquet. 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.
This work involved the isolation, identification and characterization of non-Saccharomyces yeasts from spontaneous alcoholic fermentations. These ‘wild yeasts’ play an important role in Port production, dominating the early stages of fermentation. The objectives of the project were to isolate, identify, characterize and select the best yeast strains to maximize quality complexity, whilst preserving terroir characteristics.
Sample collection (2011-2016) involved taking samples of spontaneously fermenting grape must, shortly before fortification, with preservation by freezing in glycerol at -50ºC. 20Kg Spontaneous fermentations were carried out in our R&D Micro-Winery.
A fast-track screening of samples was achieved through sensory evaluation of the finished fortified Ports, allowing selection of only the best corresponding preserved examples of yeasts to be isolated and characterized.
Our biotech partner, Bocant, isolated and characterised 500 yeast strains from 12 non-saccharomyces species (1-3), selecting only the best examples with most promising enological attributes (4). Four posters were presented at different national and International conferences.
Maximising Terroir Yeast Complexity in Port Production
The successful isolation, characterization and application of the best non-saccharomyces strains, has high-lighted the synergic importance of the terroir biome in the production of quality Port wines. Biomass was produced for the most 16 promising strains, representative of the 4 principle native species, which were inoculated individually and collectively, catalyzing fermentation, resulting in distinctive wines with very promising organoleptic properties (see posters 5-7 below).
We are conducting further trials to increase the scale of our use of indigenous yeasts in our Port fermentations.
Acknowledgements: Funding Support - This study was financially supported by EU in the frame of the Portugal 2020 (SI I&DT) programme. POCI-01-0247-FEDER-017736
Key findings & posters
(1) Exploring Genetic and Phenotypic Biodiversity of Non-Saccharomyces Yeasts from Port Wine. Mateus,D.D.; Sousa,S.; Coutinho,R.; Coimbra,C.; Rogerson,F.S.; Simões,J. Microbiotec 2017 – Universidade Católica Portuguesa - Porto, December 7-9, 2017.
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(2) Selection of Non-Saccharomyces Wine Yeasts from Port Wine. Mateus,D.D.; Sousa,S.; Coimbra,C.; Rogerson,F.S.; Simões,J. American Society of Enology & Viticulture – Annual Meeting at Monterrey, California, June 20-21, 2018.
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(3) Porto Não Saccharomyces - Seleção de Leveduras Não Saccharomyces Endógenas ao Vinho do Porto. AGRI CimeiraPT - Cimeira Nacional de Inovação na Agricultura, Florestas e Desenvolvimento Rural - AGRO INOVAÇÃO, 26 outubro, 2018
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(4) Selection of Native Non-Saccharomyces Yeast Strains for the Production of Port Wine. Simões,J.; Mateus,D.D.; Sousa,S.; Coimbra,C.; Rogerson,F.S. 42nd Congress of Vine and Wine, Geneva, Switzerland, July 15-19 2019.
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(5) Shedding Light on Port Wine Aroma Production Complexity – Terroir versus Yeast Impacts. Costa,C.; Mateus,D.; Sousa,S.; Rogerson,F.S.S.; Coimbra,C.; Simões,J; Rocha S.M. American Society of Enology & Viticulture – Annual Meeting at Monterrey, California, June 20-21, 2018.
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(6) Distinguishing the Complex Aroma of Port Wine. Costa,C.; Mateus,D.; Sousa,S.; Rogerson,F.S.S.; Coimbra,C.; Simões,J.S.; Rocha S.M. Oeno IVAS 2019 – Bordeaux Junho 2019.
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https://www.researchgate.net/publication/337947974_Distinguishing_the_Complex_Aroma_of_Port_Wine
(7) Exploring Douro Biome Terroir Complexity: Constructing Quality Port Wines using Selected Endogenous Non-Saccharomyces. Costa,C.; Mateus,D.; Sousa,S.; Silva,R.; Coimbra,C.; Simões,J.S.; Rocha S.M.; Rogerson,F.S.S. 17th Australian Wine Industry Technical Conference; Adelaide 21-24 July, 2019.
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