Exploring Ultrasound Treatments as a Prefermentative Technique to Enhance the Phenolic Composition and the Taste Sensory Attributes of Malvazija Istarska Wines

Six different vinification treatments were applied to evaluate the effect of prefermentative ultrasound treatments on bioactive compounds and taste sensory attributes of autochthonous Croatian grape variety Malvazija istarska. Four of them were based on the application of a prefermentative ultrasound technique on cooled cryomacerated mash (at 10 °C for 24 h) as follows: ultrasound treatments of 70% amplitude for 80 min (US80-70%) and 160 min (US160-70%) and ultrasound treatments of 100% amplitude for the same durations as the previous (US80-100% and US160-100%). The research also included a control treatment C (wine produced using standard white winemaking technology without maceration) and a cryomaceration treatment lasting one day at 10 °C (CRIO). Phenolic compounds in wine were analyzed by HPLC-DAD-FLD, total phenolic content (TPC), antioxidant activity and color intensity by UV/VIS spectrophotometry, and sensory evaluation was performed using the QDA and 100-point O.I.V./U.I.O.E. methods. Ultrasound-treated wines exhibited the most pronounced increases in TPC, antioxidant activity and color intensity, as well as total hydroxycinnamic and hydroxybenzoic acids, flavonols, flavan-3-ols, stilbenes and the total HPLC phenolic concentration. All wines obtained after ultrasound treatments received the highest scores by both sensory methods, in the majority of sensory attributes, especially the US160-100% treatment. The differences observed between treatments indicate that both ultrasound amplitude and duration play a key role in optimizing extraction of phenolic compounds and improving sensory attributes of the wine. The results indicate that ultrasound treatments significantly enhance the bioactive composition and sensory profile of Malvazija istarska wines, highlighting their nutritional, health-related, and market potential.