The chemical and mechanical effects of ultrasound are interesting in the food industry. This work attempts to study new applications on grapes as the raw material and then in the stabilization process.
Phenolic compounds extracted from grapes by means of disruption of the cell wall due to pressure alternance and cavitation were studied. The tests carried out showed an improvement in the extraction of polyphenolic substances, with a reduction in the duration of traditional maceration in the cellar.
The US technology causes a direct cavitational damage to microbial cell membranes with leakage of its content and sonochemical structural modifications of the liquid medium. US could accelerate the release of protective colloids (polysaccharides, glycopolysaccharides and proteins) and stabilize wine.
This study, focused on the ultrasound effects on wine lees, verifies the lytic effect on yeast cell structures and the possibility of accelerating the protective colloids release. Moreover,
these effects were compared with the usual practices of aging wine over lees and with the
enzyme treatment of lees by means of β-glucanases able to facilitate the release of intracellular components.
Ultrasound treatment on wine lees resulted in an increase in total colloids, proteins, and polysaccharides in the medium with a reduction in the colloids particle diameter. These results were mainly correlated with treatment duration rather than its intensity.
The vibrations provoked by waves pressure during the treatment could give off enough energy to stabilize tannin-tannin and tannin-anthocyanins polymers in wine.
We also investigated effects of US on red wines, in order to understand how to speed up the aging reactions and hence reduce the time between production and sale.
It was found that a few minutes ultrasonic treatment probably promotes an increase in the amount of the catechins, the depolymerization of the tannins and a change of the astringency.
