Effect of Low-Frequency Ultrasonication on Red Wine Astringency

Ultrasound and its coupled oak blocks treatment based on absorbed energy density for comprehensive insight and scale-up consideration of phenolic and astringency profiles in red wines

Ultrasound and ultrasound-coupled oak blocks techniques on the phenolic and astringency profiles of Petit Verdot wines were discussed in this study. The relationship between techniques at varying absorbed energy density (AED) gradients and astringency was revealed, elucidating potential molecular mechanisms regarding compound interactions. Ultrasound was found to promote phenolics degradation and condensed tannins maturation, while oak blocks improved ellagitannins release into wines, facilitating polycondensation reactions to form larger complexes. Phenolics binding to salivary proteins decreased at low AED values (0-33.07 J/mL), enhanced at high AED values (66.14-165.34 J/mL), and reduced salivary proteins' precipitation ability. Treated samples significantly altered astringency's global terminology and sensory attributes across oral regions, with oak blocks enriching the astringency hierarchy. Multivariate analysis identified an optimal ultrasound AED of 0 to 33.07 J/mL, and an effective PLS-DA model was developed for industrial scale-up considerations, aiming to cost-effectively enhance the organoleptic quality of wines.

Ultrasound-assisted production of alcoholic beverages: From fermentation and sterilization to extraction and aging

Ultrasound is sound waves above 20 kHz that can be used as a nonthermal ''green'' technology for agri-food processing. It has a cavitation effect, causing bubbles to form and collapse rapidly as they travel through the medium during ultrasonication. Therefore, it inactivates microorganisms and enzymes through cell membrane disruption with physicochemical and sterilization effects on foods or beverages. This emerging technology has been explored in wineries to improve wine color, taste, aroma, and phenolic profile. This paper aims to comprehensively review the research on ultrasound applications in the winery and alcoholic beverages industry, discuss the impacts of this process on the physicochemical properties of liquors, the benefits involved, and the research needed in this area. Studies have shown that ultrasonic technology enhances wine maturation, improves wine fermentation, accelerates wine aging, and deactivates microbes while enhancing quality, as observed with better critical aging markers such as phenolic compounds and color intensity. Besides, ultrasound enhances phytochemical, physicochemical, biological, and organoleptic properties of alcoholic beverages. For example, this technology increased anthocyanin in red wine by 50%. It also enhanced the production rate by decreasing the aging time by more than 90%. Ultrasound can be considered an economically viable technology that may contribute to wineries' waste valorization, resource efficiency improvement, and industry profit enhancement. Despite numerous publications and successful industrial applications discussed in this paper, ultrasound up-scaling and applications for other types of liquors need further efforts.