Pilot-scale ultrasound-assisted extraction of protein from soybean processing materials shows it is not recommended for industrial usage

•Ultrasound significantly enhanced protein yielded from okara in pilot-scale trials.•Intact cells were still visualised after pilot-scale sonication of okara solution.•Particle size of resultant soybase reduced after sonication at pilot-scale.•Disparity of results from lab and pilot probe caused by different energy inputs.•Ultrasound is not considered an optimum process for industrial soymilk production.

Unit operations to enhance protein extraction within the food industry are vital to improve current processes, especially for cost reductions and sustainability. Here a study of ultrasound-assisted extraction (UAE) from soy slurry and okara produced at pilot-scale and further processed using a lab or pilot-scale probe system is presented. Confocal imaging and particle size measurements were used to study the physical effects of UAE on these soy processing materials. Ultrasound at pilot-scale was infeasible for soy slurry, in contrast to lab-scale. UAE from okara solution significantly increased protein yield by 4.2% at pilot-scale (p < 0.05). Okara solution flow rate and okara concentration also significantly improved the protein extraction yield. During lab-scale sonication of okara solution, a greater energy intensity resulted in a higher yield of up to 40% after 15 min treatment. Considering total extraction yields at pilot-scale during soybase production, ultrasound is not considered viable for industrial processing.