Soybean okara is a by-product generated during tofu or soymilk production processes. It contains about 50% dietary fiber, 25% protein, 10% lipid, and other nutrients. Due to its high protein content and low production costs, okara is a good raw material for protein extraction. Hence, the ultrasound protein extraction was carried out at 20, 60, and 80 °C and a greatly enhanced of their yields was achieved. The ultrasound treatments at different temperatures modified in a significant way the protein secondary and tertiary structure. The atomic force microscope (AFM) analysis demonstrated a significant morphological transition from well-defined single round structures to highly aggregated ones after the ultrasonication at the highest temperature, suggesting that these aggregates possess more hydrophilic surfaces and more hydrophobic cores than the untreated sample. This feature was confirmed by measuring their water contact angles and wettability. Hence, the improvements of protein solubility and water binding capacity appears to depend on the temperature in a similar way in the ultrasound extraction. On the contrary, no protein viscosity change was observed. The improvement of peptides generation and the different amino acid exposition within the protein after the ultrasound process led to an increase of the antioxidant properties of the samples and to a reduction of their phytic acid content. The integrated strategy applied in this study, allows to foster the okara protein obtained after ultrasound extraction as valuable materials for new application and provides, therefore, a more sustainable way to solve the environmental criticism related to the huge quantities of okara produced annually.

Ultrasound-aided extraction of soybean okara byproduct: analysis of their physicochemical and conformational changes

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.