Using high-power ultrasounds in red winemaking: Effect of operating conditions on wine physico-chemical and chromatic characteristics

This study presents the application of high-power ultrasounds (US) to crushed grapes using winery-scale equipment and studies, for the first time at this scale, how the frequency of the ultrasounds affects the extraction of phenolic compounds from grapes and the chromatic and physico-chemical characteristics of the finished wines, in an attempt to optimize the maceration process. The results showed how US modified the physical characteristics of the grape skin, facilitating phenolic extraction and improving the wine chromatic characteristics but only produced slight differences in the physico-chemical characteristics of the finished wines. The two different frequencies applied led to some differences in the wine phenolic composition, especially higher tannin extraction at 20 kHz whereas anthocyanin extraction was favoured at 28 kHz. Wines made with sonicated grapes and 72 h of skin maceration time were chromatically very similar to control wines with four more days of skin contact, indicating that this technological process may increase the working capacity of the winery by allowing a reduction of more than 50% in the maceration time.

Automated summary

This study demonstrates that high-power ultrasounds can modify the physical characteristics of grape skin, facilitate phenolic extraction, and enhance wine chromatic features, while only producing slight differences in the physico-chemical characteristics of the finished wines. Different ultrasound frequencies lead to variations in the phenolic composition of wines, with higher tannin extraction at 20 kHz and favored anthocyanin extraction at 28 kHz, ultimately reducing maceration time by over 50%.