Novel plant protein products are currently of high interest due to consumer preference over the use of animal proteins, but the functionality of plant proteins remains a challenge. Ultrasound (US) has become a technology of interest to the food industry due to its ability to remove water and solvents without significantly raising the temperature of the load. The effect of ultrasound drying of vegetable protein gels on the solubility of resulting dried proteins was investigated. Protein gels were prepared by hydrating almond, lentil, and pea protein concentrate powders (10-20% w/v) for 2 hours. Ethanol (30-80% v/v) was then added to the protein solution. All proteins formed instantons gels immediately upon contact with ethanol. Viscoelastic properties of ethanol-induced gels were determined with an ARES-G2 rheometer. Ultrasound drying of protein gels was performed with a custom-designed direct contact system consisting of a transducer box that vibrated at 40 kHz (1kW). The transducer box was submerged in a water jacket for temperature control. Drying temperature was 28C, drying time was 8 minutes. On average, final moisture content was 1% and residual ethanol was 0.001 mg/g. The microstructure of US dried samples was examined by CT scan. It consisted of thin films of uniform structure. US drying significantly enhanced the solubility of plant protein gels, from 9 g/100mL for pea protein concentrate to 40g/100mL for US dried pea protein gel, on average. This work aims to enhance the functionality of vegetable protein powders by using non-thermal processing.
