Intensification of protein extraction from soybean processing materials using hydrodynamic cavitation

- High pressure homogenisation disintegrated all intact soybean cells.
- Total protein yields of up to 90% could be achieved by okara solution treatment.
- 1 pass at 100 MPa was sufficient to disrupt all soybean cells of slurry or okara.
- Based on productivity treatment of slurry is more valuable for industry than okara.

High pressure homogenisation (HPH) has been investigated for its potential to aid the aqueous extraction of protein and other components from soybeans. HPH treatments (50-125 MPa) were applied to soy slurry and okara, the diluted waste stream from soybase production. Extraction yields of oil, protein and solids were calculated, and the feasibility of the technology was assessed. The most productive HPH treatment investigated improved extraction yields of protein up to 82% with a single pass of soy slurry at 100 MPa. In comparison, a maximal protein extraction yield of 70% has been achieved previously using ultrasound at lab-scale for 15 min (20 kHz, 65 W according to manual, 13 mm probe tip) (Preece et al., in press). Results showed a particle size reduction upon HPH and disruption of intact cells, confirmed via confocal laser scanning microscopy. Multiple HPH passes of soy slurry caused an increase in dynamic viscosity and a small increase in particle size probably due to cell wall swelling, resulting in decreased separation efficiency and consequently a reduced extraction yield. HPH offers extraction assistance, with more promising results reported in comparison to ultrasound-assisted extraction of soybean processing materials.Industrial relevanceImprovement of current soybean processing is desirable on an industrial level to better use available raw materials and reduce waste production. This study shows the effects of a technology already widely employed in industry for other benefits, such as fine emulsion production and microbial cell disruption. High pressure homogenisation was carried out on a lab-scale on soybean processing materials which were prepared in a pilot plant, with similar feed compositions to those produced at an industrial scale.