Impact of high pressure homogenization on physical properties, extraction yield and biopolymer structure of soybean okara

The effect of high pressure homogenization (HPH) on soy okara was studied. To this purpose, okara dispersions (10 g/100 g) were subjected to 1 pass at 50, 100 and 150 MPa and to 5 passes at 150 MPa. Samples were analyzed for stability, particle size, microstructure, and viscosity. Results highlighted that the increase of HPH intensity was associated with the structural disruption of okara particles, leading to physically stable homogenates having increasing viscosity. This was mainly attributed to an increase in okara solubility, due to fibre and protein release. The latter resulted almost complete, reaching values up to 90% of the protein originally entrapped in okara matrix. Absorbance at 280 nm, SH groups and dimension of proteins revealed that HPH treatments favoured the extraction of the main protein fractions even if, at the higher intensity level, extracted proteins probably underwent conformational changes and reassembling phenomena.