The use of microwaves during the maceration of Cabernet Sauvignon wines for improving their chromatic characteristics

Abstract

The use of new technologies such as microwaves (MW) arose in recent years as an efficient alternative to reduce the use of sulfur dioxide (SO2) and as a method for improving wines in terms of color and aroma [1, 2]. MW (non-ionizing electromagnetic waves with frequencies between 300 MHz and 300 GHz) have been widely applied in the food industry in order to reduce processing time and favor food preservation. The MW cause the migration of ions and dipoles generate frictional forces increasing the temperature. This thermal energy can break bonds between compounds, being able to favor the breakage of the cell wall of the grape skin. This would favor the extraction of compounds of interest, allowing wineries to reduce maceration time and increasing their production capacity. In this context, our work focuses on studying the capacity of MW to favor the extraction of phenolic compounds from red grapes of the Cabernet Sauvignon variety in order to obtain wines of high color quality with short maceration times.For this, the chromatic parameters and phenolic composition of wines elaborated with MW treated grapes were studied and compared with a control vinification. This test was carried out using two different maceration times: 72 hours and 7 days. The MW treatment in all cases consisted of applications lasting 12 min at 700 W using a domestic oven avoiding temperature increases above 40ºC. All assays were performed in triplicate and wines were analyzed by spectrophotometry and high-performance liquid chromatography at the time of bottling.The results obtained showed an increase in the content of phenolic compounds and color intensity (CI) in the wines obtained from grapes treated with microwaves respect to their controls for both maceration times (12% and 15% increase in CI, respectively). No significant differences were observed for none of the chromatic parameters studied between the wine obtained after a MW treatment and macerated for 72 hours and the control wine with a four-day longer maceration, being of special interest the CI and the total polyphenol index (TPI) (CI: 16.16 vs 17.18 and TPI: 45.22 vs 47.05, respectively).For this reason, this study shows the possibility of reducing the maceration time without losing quality in the wines obtained when MW are used.

References

[1] Muñoz García, R.; Oliver Simancas, R.; Díaz-Maroto, M.C.; Alañón Pardo, M.E.; Pérez-Coello, M.S. (2021). Foods, 10, 1164.
[2] Carew, A.L.; Gill,W.; Close, D.C.; Dambergs, R.G. (2014). Am. J. Enol. Vitic., 65, 401–406.