Innovations on red winemaking process by ultrasound technology

Abstract

High power ultrasound has been recently recognized one of the most promising technologies in winemaking processes, especially after the recent OIV resolution, concerning the application of ultrasounds on crushed grapes to promote the extraction of skin compounds. The present work resumes the pluriannual researches carried out at laboratory and industrial scale, aimed to study the effect of ultrasounds during different steps of the red winemaking process, using respectively: a static laboratory sonifier (20 kHz) and a pilot plant at continuous mode (27 kHz).  

A number of technological experiments were carried out on different grape cultivars from different wineries and producing areas, to study properly the potential effectiveness of ultrasounds on the maceration process. In all the industrial experiments, the crushed grapes were split into equal and homogeneous aliquots by an appropriate Y-valve to ensure the comparison of untreated and sonicated samples. Sonication induced a higher extraction rate of polyphenols compounds from grape skins and seeds, and allowed a 40-60% reduction of the maceration time, giving besides significant advantages from an energetic and economic point of view. Ultrasound showed nonetheless remarkable advantages on color stability and sensorial characteristics. 

The effect of ultrasound amplitude and treatment time was also studied, at laboratory scale, on anthocyanins, tannins, and color stability indices. Anthocyanins and chromatic properties are preserved by ultrasounds and a potential chemical effect on the evolution of some analytical indices during wine aging has been highlighted. 

Ultrasound could be considered as an emerging technology aimed to reduce the inputs of red winemaking process and to develop a novel practice.