Search

[Background] This research was aimed to study the influence on grape and wine quality and on the fermentation processes of the application of a preventive biological treatment against Botrytis cinerea in Tempranillo Rioja grapevines. For this purpose, a biofungicide containing Bacillus subtilis QST713 was applied twice to the vineyard. [Results] Results were compared with non‐treated samples from the same vineyard and with samples treated with a chemical fungicide composed of fenhexamid. Data showed that general grape quality and spontaneous alcoholic fermentation performance were not influenced by either fungicide application. The chemical fungicide had a considerable influence on the clonal diversity of Saccharomyces cerevisiae species, which led to the alcoholic fermentation. Furthermore, it caused longer malolactic fermentation than with the biological fungicide and in the control. The biofungicide made malolactic fermentation 1 day shorter because the establishment of the commercial lactic acid bacteria used as a starter culture was total. After malolactic fermentation, the wines did not show significant differences in general oenological parameters. [Conclusion] Preventive biofungicide treatment against B. cinerea did not negatively influence the quality of grapes and wines and the fermentation processes. Therefore, biological control of B. cinerea with B. subtilis applied on grapevines could be advisable in oenological terms, The Government of La Rioja supported this work under the grant of Escribano‐Viana R. BOR no. 34, 13 March 2015. We also thank the Bayer Crop Bioscience S.L. for funding support and for the application of their fungicides on the grapevines

[Background and Aims] The antiseptic effect of the addition of colloidal silver (CAgC) alone or in combination with a small quantity of sulfur dioxide (SO2) was examined in both vinification and storage of red wines. [Methods and Results] Four treatments of grapes and wines with SO2 and CAgC alone or in combination with a small quantity of SO2 were established. All treatments of grapes provided similar control of yeast and lactic acid bacteria, however, the three treatments with CAgC were more effective in the control of acetic acid bacteria. The addition of CAgC did not affect fermentation, and the wines had physicochemical, aromatic and sensory characteristics similar to that of the control, but a lower alcohol content. None of the treatments maintained control of bacteria during storage. After 1 month of stabilisation and 4 months of storage, the wines produced with CAgC had a higher colour intensity and a lower concentration of both anthocyanins and total polyphenols. Moreover, the final wines showed little difference in volatile and biogenic amine composition, which affected neither their quality nor their sensory characteristics. [Conclusions] Under the conditions studied, addition of SO2 could be reduced or replaced by CAgC. Overall, wines elaborated with CAgC showed no microbiological problems, and moreover, they had a higher colour intensity and similar aromatic composition and biogenic amines concentration to that of the control; their sensory characteristics were well rated. [Significance of the Study] Colloidal silver could be a promising antiseptic in the elaboration and storage of young wines. © 2013 Australian Society of Viticulture and Oenology Inc.