Yeast, bacterial and plant resources for sustainable winemaking processes

During the ROUND TABLE #4 - Yeast, bacterial and plant resources for sustainable winemaking processes, held at Macrowine 2021 we had four interesting presentations from across the world. 

Rocio ESCRIBANO VIANA - ICVV, Instituto de Ciencias de la Vid y el Vino, University of La Rioja (Spain) - Bioprotective effect of non-Saccharomyces yeasts in wines made without SO₂

The objective of this work was to evaluate the bioprotective effect of a mixed inoculum of non-Saccharomyces  yeasts (Torulaspora delbrueckii and Lachancea thermotolerans 70/30) in two consecutive vintages (2018 and 2019). Three strategies were carried out in triplicate: spontaneous fermentation in sulphited must, spontaneous fermentation in non sulphited must and inoculated fermentation (non-Saccharomyces mixed inoculum) in non sulphited must. In all cases, after 72 hours of fermentation the vats were seeded with a commercial  Saccharomyces cerevisiae yeast. The presence in the medium of lactic and acetic bacteria and the chemical composition of the wines were evaluated. What did the obtained results indicate? Was the bioprotective effect of non-Saccharomyces yeasts inoculation determined by the success of the implantation?

Vasileios ENGLEZOS - University of Turin, DISAFA (Italy) - Effect of environmentally friendly vineyard protection strategies on yeast ecology during fermentation

This study evaluated the effect of a wide range of environmentally friendly products applied in the vineyard on grape yeast ecology at harvest, as well as during spontaneous and inoculated fermentations in winery and laboratory scale conditions. Yeast ecology was investigated using culture-dependent (plate counts) and -independent (Next Generation Sequencing) methods. Main oenological parameters and volatile compounds were monitored during spontaneous and inoculated fermentations. Spearman’s correlation was used to assess associations between ASVs changes and chemical composition observed over fermentation. Which significant differences were observed among the alternative and conventional treatments, compared to the controls, in terms of yeast population and biodiversity? Could yeast ecology in fermenting musts be correlated to specific antifungal products and inoculation protocol employed? 

Ana Belén BAUTISTA-ORTÍN - University of Murcia (Spain) - Effect of plant fining agents in the must flotation process. Functional characterization

Flotation is one of the most used processes for clarifying white grape must after the pressing process. To date, gelatine is the more used fining agent, its action being improved when combined with bentonite and silica sol. However, in recent years, there is a growing commercial interest in replacing this animal origin protein with plant proteins, due, on the one hand, to the problems associated with allergies and, on the other hand, also thinking in the vegan wine consumers. However the efficiency of plant proteins as floculating agents are lower than gelatine and varies among them,  the reason behind the different behaviour being unknown. The objective of this work was to compare the flocculating efficiency of a commercial gelatine, a pure pea protein and the same pea protein chemically modified and to relate this efficiency  to their amino acid composition and protein functions.
 

Fernando SALAZAR - Laboratorio de Fermentaciones Industriales, Facultad de Ciencias Agronómica y de los Alimentos, Pontificia Universidad Católica de Valparaíso (Chile) - Application of UV-LED in wine as an alternative to sulphur dioxide

Sulfites (SO₂) are commonly used in the wine industry to preserve products during storage for antiseptic and antioxidant purposes. However, the presence of sulfites at varying concentrations has been linked to allergic reactions in some consumers, such as dermatitis, urticaria, abdominal pain, among others. UV-LED irradiation has been is an attractive technology of non-thermal nature and is an alternative to partially or totally replace the addition of SO₂ to wine, due to its antimicrobial effect. In this study, the effect of the UV-LED irradiation on the activity of Acetobacter aceti ATCC 15973 of white wine (Sauvignon blanc) and red wine (Pinot noir) was evaluated. A laboratory scale static UV LED irradiation system was designed, composed of four diodes with wavelengths of 278 nm (8-12 mW), 275 nm (3-5 mW) and 265 nm (1-3 mW) and irradiation times of 10, 20 and 30 min. What di the results indicate? Could this technology  be an advantageous alternative to avoid the excessive use of sulphites in wine products?

Videos of the rounda table held during Macrowine virtual (June 23-30, 2021)

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