Preliminary Study Regarding the Optimisation of the Accelerated Ageing of Sugar Cane Spirit by Applying Ultrasound-Assisted Extraction and White Oak Chips (Quercus alba)

Abstract

The ageing of alcoholic beverages is a common practice in order to increase their quality and characteristic flavour. These changes during the ageing process are caused by a series of chemical reactions that take place between the wood extractable compounds, the distillate and the oxygen that passes through the wood. However, this process is slow and can take several years. This research focussed on optimising the use of Quercus alba chips and ultrasound in the accelerated ageing process of sugar cane spirit using the response surface methodology. The effect of temperature and ultrasound was analysed using a two-level factorial design type 22. Subsequently, the accelerated ageing process was optimised using response surface methodology. Temperature and time of exposure to ultrasound energy were the selected independent variables. As a response variable, the total polyphenol index (TPI) was selected. In addition, the CIELab method was used to determine the chromatic characteristics (L*, a*, b*) of the aged samples. Toasting had a negative effect on the TPI, whilst the oak chips that were untoasted and treated with ultrasound obtained the highest TPI yield (80.5–81.5 mg GAEeq/L). The TPI values obtained through the use of the accelerated ageing method suggest that this is more efficient than the traditional ageing process, as it leads to a decrease in the maturation period of sugar cane spirit. Regarding colour properties, a higher intensity of colour was found in the samples where the accelerated ageing method was applied. The temperature and sonication time of 48.9 °C and 18.8 min were the optimal parameters in order to obtain a TPI value (85 GAEeq./L) comparable to the Brandy Solera Reserve (12–18 months for the traditional method) for sugar cane spirit using the accelerated method. The findings of this research can contribute towards the development of new ageing processes of distillates, mainly in terms of decreasing ageing times.