Ultrasound has been used to intensify the extraction of phenolic compounds from many agro-food products. However, there is still a lack of understanding on how the ultrasonic energy is influenced by blends of different solvents and how this impacts the extraction process. This work studied the effect of ethanol, acetone and hexane blends on the ultrasonic energy generated during the extraction of phenolic compounds from Mango peel, using an ultrasonic-assisted extraction (UAE) and a conventional solvent extraction (CSE).A simplex centroid mixture design and a special cubic regression model were used to evaluate the total phenolic compounds (TPC), antioxidant activity (AA) and ultrasonic intensity (UI) as a function of the solvents proportions. The greatest TPC was obtained with the ethanol-acetone blend (60-40%) for CSE (205.08 mg GAE/100 g DM) and UAE (1493.01 mg GAE/100 g DM). Likewise, an increase (avg. 630%) was observed in TPC when the ultrasound was applied for all solvents and their blends. The TPC showed a good correlation (R 2 =0.81) with the UD, with higher UD resulting in larger amounts of TPC extracted.Nevertheless, for the ethanol-acetone blend there was a decrease of 14.2% of the AA for the UAE, which could be due to the sonochemical reactions taking place at the high UD achieved for that blend. The results of this work indicate that the solvent composition and use of ultrasound should be carefully selected to achieve the desired extraction objectives.

Highlights A Nusselt ( Nu ) correlation was developed for US-assisted heating/cooling processes. The performance of Nu equation was tested with different immersion media. Heat transfer enhancement by US is limited at high duty cycles and fluid velocities. The Nu equation was applied to analyze the US-accelerated heating of dry-cured ham. Heating of ham is improved by increased h values and direct absorption of US power.