Study of a laboratory-scaled new method for the accelerated continuous ageing of wine spirits by applying ultrasound...

During the ageing of brandies, many physicochemical processes take place involving the distilled spirit and the wood of the casks. Because of these reactions, the polyphenolic content of brandies and their content of organic acids increase with the ageing. These reactions are slow, and the ageing of high-quality brandies takes several years. In this paper, the development of a system that uses the circulation of the wine distillate through encapsulated American oak chips and the application of ultrasound energy with the aim of producing aged wine spirits has been carried out, and the influences of the operation variables over the characteristics of the produced drink have been measured. With that proposal, the influence of different powers of ultrasound, and also the influence of the movement of the liquor through oak chips, was determined first. This way, the results show that higher powers of ultrasound, of nearly 40W/L, in addition with the movement of the spirit, improve the extraction of phenolic compounds in a 33.94%, after seven days of ageing. Then, applying Youden and Steiner's experimental design, eight experiments of ageing were performed, and the samples obtained by this new method were analysed to obtain information related to their physicochemical and oenological characterisation in order to determine the experimental conditions that produce the best ageing results. This way, the best spirit produced by this new method of ageing is obtained with a high alcoholic strength of the distilled wine and a high quantity of oak chips, and with room temperature and high flow rate. In addition, the presence of oxygen in the sample and the absence of light increase the quality of the produced spirit. Finally, the application of ultrasound energy in large pulses is related with the improvement of two important ageing markers: the intensity of the colour and the TPI. As a last experiment, we applied this ageing method to five varietal spirits. The sensorial analysis of aged samples showed the aged spirits had better ratings than the initial distilled wine.