Sweet Sherry wines from Pedro Ximénez and Muscat sun and chamber-dried grapes during vintages 2009 and 2010 were aged in American oak wood for 12 months. Their volatile content was periodically analyzed using SBSE-GC-MS. Cluster analysis and principal component analysis demonstrated that the volatile compounds considered can be used to detect grape variety and vintage. Principal component analysis for each grape variety, clearly differentiated aging time and vintage. Drying type was the least significant factor. Sweet wines produced using chamber driers were from Pedro Ximénez and Muscat grapes provides similar in volatile constituents as those produced by traditional process.

In this study, a climate chamber, as an alternative method, has been used to dry raisins and the sensory profiles of the sweet sherry wines obtained have been evaluated. Other important factors, namely grape variety, vintage, vinification conditions, as well as the ageing method and its length of time, have also been considered. When heavy rainfall had been registered, the musts extracted from grapes dried under controlled conditions in a climate chamber showed a lower intensity of the musty off-odor compared to those elaborated with sun-dried grapes. The wine fermented at low temperature with Saccharomyces bayanus scored the highest in citric and floral notes, and this was preferred over all the other wines that were evaluated. The wines aged in oak barrels were preferred to both, wines aged in the presence of oak chips as well as those aged without any wood contact. The use of climate chambers to dry the grapes that are going to be used for the elaboration of sweet wines appears to be an advantageous alternative to the traditional method, since it allows a more precise control of the process and highly valued sweet wines from a sensory point of view are obtained thereby.

During the drying process of raisins, the grapes are subjected to climatic variations that can result in heavy infections of some fungal species that produce ochratoxin A (OTA), a powerful toxic metabolite, whose maximum permitted content is set by the European Union at 2.0 μg/L for grapes, wine and other drinks derived from the grape. The aim of this paper is to optimize the process of making sweet wines in order to minimize the content of ochratoxin A. The results reflect a reduction of the OTA content in grapes dried under controlled conditions in a climatic chamber up to 24% compared to those sunned in the traditional way. A decrease of the concentrations of OTA is also observed during the processes of vinification. Those wines with prefermentative maceration reached a higher OTA content than the wines without maceration, but unexpectedly were not those preferred from a sensorial point of view. In addition, the process of aging in oak casks has been shown to serve as a natural method for reducing the OTA content of these wines.

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Background and Aims:Ethyl carbamate (EC) is a known carcinogen that has been found in wines. The aims of this study were: (i) to study the effect of fermentation under different enological conditions on the EC concentration in sweet Sherry wines made from the two grape cultivars, Muscat and Pedro Ximénez, during three consecutive vintages (2008)(2009)(2010); and (ii) to investigate the evolution of EC concentration during ageing in oak and in stainless steel. Methods and Results: Before and during ageing, the wines obtained were periodically sampled, and EC content was determined by HPLC with fluorescence detection. Mean values of EC ranged from 6.16 μg/L for samples after alcoholic fermentation to 120 μg/L for samples after 28 months of ageing in oak. Data were submitted for ANOVA and cluster analysis. It has been observed that the various factors considered (vinification conditions, ageing type, ageing time, grape cultivar and vintage) have significant influence on the EC concentration of the wines. The use of Saccharomyces bayanus instead of Saccharomyces cerevisiae reduced the EC concentration significantly. Both the use of nutrients and skin contact with pectolytic enzymes increased EC concentration. Ageing increased the EC content for all vinification conditions. Conclusions: Ageing was the most significant factor affecting EC concentration of the wines. Wines made from Muscat, fermented with S. cerevisiae and aged in oak cask for up to 28 months presented the highest EC concentration. Significance of the Study: The ageing of sweet Sherry wines in oak results in a concentration of EC higher than that from ageing of similar wines in stainless steel.Keywords: ethyl carbamate, oak cask, stainless steel, sweet Sherry wine, yeast strain 396Ethyl carbamate in sweet Sherry wines