DEL MONACO silvana Maria
congresos y reuniones científicas
Simposio; 29th International Specialised Symposium on Yeasts; 2011
Introduction. Malic acid and tartaric acid are the most abundant organic acids in grapes and wines, and significantly influence its sensory properties as well as its physicochemical and microbiological stability (1). Particularly, malic acid content is higher in musts obtained from cooler regions and also in earlier Vitis vinifera varieties, like Pinot noir (2). Therefore, the amount of malic acid in the final product is a great concern for local winemakers and researchers. Recently, various yeast strains have been investigated as alternative agents for malic acid degradation in wine. We isolated a strain of Issatchenkia orientalis (Pichia kudriavzevii) named ÑNI15 from a vineyard in the North Patagonian Region, which proved its competence to metabolize malic acid from synthetic musts at a laboratory scale (3, 4). In this context, and with the aim to develop indigenous mixed starters for high quality red winemaking, we studied mixed fermentations with patagonian Issatchenkia orientalis ÑNI15 and Saccharomyces cerevisiae ÑIF8-LVI stains to prove their enological capabilities. Methods. I. orientalis (Pichia kudriavzevii) ÑNI15 and S. cerevisiae ÑIF8-LVI were isolated from ?Del Añelo? cellar, located in the North Patagonian Region, Argentina. Microvinification studies were carried out in synthetic (5) and natural Pinot noir musts from the Comahue region (200 mL). Five inoculation strategies were conducted, which included sequential cultures (SSI: 1° S. cerevisiae - 2° I. orientalis; or SIS: 1° I. orientalis - 2° S. cerevisiae), simultaneous mixed cultures (Co), and control monocultures (Io, Sc). The evolution of fermentations was determined by weighting, yeast growth by viable yeast count, organic acids by HPLC, ethanol by GC and glucose, fructose, L(-)malic acid and glycerol content by enzymatic kits. The sensory evaluation of the wines obtained was performed by a panel of four judges from INTI (Instituto Nacional de Tecnología Industrial) (6). Experiments were carried out in duplicates. Results and discussion. Results evidenced that I. orientalis, when present during the fermentation, yielded wines with higher sensory and physicochemical quality. This yeast was able to metabolize malic acid, reaching higher consumption percentages in natural musts than in synthetic ones (54,26 ± 6,21 vs 43,21 ± 3,38%; 43,89 ± 3,04 vs 38,68 ± 5,73%; 49,08 ± 4,43 vs 30,98 ± 5,73%; y 49,25 ± 4,58 vs 29,79 ± 8,86% for Io, Co, SIS and SSI, respectively). Wines pH showed higher values than the S. cerevisiae monocultures (3,35 ± 0,01; 3,46 ± 0,02; 3,53 ± 0,04; 3,40 ± 0,01; y 3,39 ± 0,10 for Sc, Io, CoC, SIS and SSI, respectively). The Co strategy from Pinot noir fermentation showed the best sugar consumption (96,63 ± 2,21%), and an adequate production of ethanol (11,69 ± 0,65%, v/v) and glycerol (8,87 ± 0,99 g/L). This treatment also showed a balanced composition of organic acids, with low acetic and succinic production. And finally the Co wine from Pinot noir fermentation obtained the highest sensory qualification, with citric, pineapple and red fruit notes, highlighting the Pinot noir strain characteristics. Conclusions. The results obtained evidenced a good performance of these indigenous strains to be used in mixed starters for enological purposes. Patagonian I. orientalis ÑNI15 and S. cerevisiae ÑIF8 combined produced a wine of high sensory quality and reduced malic acid content. Acknowledgements. This work was supported by Universidad Nacional del Comahue and Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET). References. (1) Pretorius, I.S. (2000). Tailoring wine yeast for the new millennium: novel approaches to the ancient art of winemaking. Yeast, Vol. 16: 675-729. (2) Ribereau-Gayon, P., Dubordieu, D., Donèche, B., Lonvaud, A. (2003). Tratado de enología. (Tomo II). Química del vino. Estabilización y tratamientos. Hemisferio Sur y Mundi Prensa. (3) del Mónaco S., Zajonskovsky I. y Caballero A. (2009) Cepas indígenas de Issatchenkia orientalis de potencial aplicación en la elaboración de vinos patagónicos. XII Congreso Argentino de Ciencia y Tecnología de los Alimentos. (CYTAL). Concordia, Entre Ríos, Argentina. Octubre ? 2009. (Proceedings) (4) del Mónaco S., Zajonskovsky I., Caballero A. (2010) Aislados patagónicos de Issatchenkia orientalis de potencial aplicación en enología. La Alimentación Latinoamericana. 286: 54-61. (5) Henschke, P., Jiranek, V. (1993) Yeast metabolism of nitrogen compounds. In: Wine Microbiology and Biotechnology. Fleet G.H. (Eds) 77-165. (6) Meilgaard, M., Civille, G., Carr, B., (2006). Sensory Evaluation Techniques. Press, C.R.C. New York, Boca Raton.