Analytical and Chemometric Characterization of Sweet Pedro Ximénez Sherry Wine during Its Aging in a Criaderas y Solera System.

Pedro Ximénez is a naturally sweet sherry wine produced in southern Spain from raisined Pedro Ximénez grape must and aged using a traditional Criaderas y Solera system. Complete analytical characterization has been useful in determining which parameters are the most influential in the aging of this wine. The organic acids, volatile compounds (higher alcohols, esters, aldehydes, and acetals), and phenolic compounds of this wine evolve during its aging, mainly through physico-chemical reactions and the contributions of wood compounds. During their aging, Pedro Ximénez sherry wines develop their organoleptic profiles, as tasting sessions have confirmed. A strong correlation between the aging of a wine and the parameters analyzed has also been corroborated through an MLR analysis. This allowed for the development of a model that, by using just 8 of the variables considered in the study, led to the determination of wine samples' ages at over 97% confidence. This constitutes a rather useful tool for wineries to control Pedro Ximénez sherry wine aging processes.

Chemometric studies of vinegars from different raw materials and processes of production.

The phenolic composition, aroma compounds, and organic acid content of 83 vinegars have been determined. Multivariate analysis techniques have been used to classify these vinegar samples according to raw material (white wine, red wine, apple, honey, alcohol, balsamic, and malt) and production process (with and without aging in wood). Cluster analysis grouped the samples according to production process. Only apple and balsamic vinegars were separated from wine vinegars. Alcohol, honey, and malt vinegars were grouped with no aged wine vinegars. Linear discriminate analysis allowed a 88% differentiation according to raw material and 100% according to aging in wood. Besides, from the results obtained, a major role of the volatile compounds in the differentiation of the vinegar samples according to their aging period in wood can be seen.

Headspace solid-phase microextraction analysis of aroma compounds in vinegar. Validation study.

Headspace solid-phase microextraction (HS-SPME) was evaluated for analysing aromatic compounds in vinegar. The fibre used (a Carboxen-polydimethylsiloxane fibre), and the analytical conditions had been optimised in a previous work. The HS-SPME procedure developed shows detection and quantitation limits, and linear ranges adequate for analysing this type of compounds. The recoveries obtained were close to 100%, with repeatability values lower than 20%. However, considerable differences have been detected between different fibres. The method was applied to a variety of Sherry wine vinegars.