Influence of ohmic heating on the structural and immunoreactive properties of soybean proteins

Ohmic heating (OH) encompasses interesting benefits towards thermal processing. Envisaging an increasing relevance of soybean protein as an alternative non-animal protein, it is important to understand how OH can contribute to the quality and immunoreactivity of soybean-derived products. This study describes, for the first time, the impact of OH when applied at different electrical frequencies (50 Hz20 kHz) and moderate electric field intensities (up to 20 V/cm), on the leakage of metals from the electrodes and immunoreactivity aspects of soybean protein isolate (SPI). This was achieved by monitoring the occurrence of electrochemical reactions and evaluating IgG-binding capacity. OH performed at 50 Hz and 95 °C induced significant alterations on the intrinsic fluorescence of SPI (p  0.05) and the release of detectable amounts of Fe/Ni, with a subsequent reduction of 36% in the immunoreactivity of Gly m TI. The occurrence of non-thermal effects, as well as the interaction between protein and trace metals, may result in a partial blockage of protein epitopes, thus impairing specific antibody binding. These findings present novel information about the importance of OH parameters, such as electrical frequency and occurrence of electrochemical reactions, which can affect the structure and immunoreactivity of SPI fractions.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 and UID/QUI/50006/2020 with funding from FCT/MCTES through national funds, and AgriFood XXI R&D&I project, operation number NORTE-01-0145-FEDER-000041 and NORTE-01-0145-FEDER 000052, co-financed by the European Regional Development Fund (FEDER) through NORTE 2020 (Northern Regional Operational Pro gram 2014/2020). This work also received financial support from the European Union (FEDER funds through COMPETE POCI-01-0145- FEDER-031720) and National Funds (FCT) through project Alle Risk Assess PTDC/BAA-AGR/31720/2017. Caterina Villa and Luís Machado thank FCT for their grants under project AlleRiskAssess (PTDC/BAA-AGR/31720/2017). Joana Costa thanks FCT for funding through program DL 57/2016 – Norma transitoria (SFRH/BPD/102404/2014). Ricardo N. Pereira acknowledge FCT for its Assistant Research contract obtained under CEEC Individual 2017.info:eu-repo/semantics/publishedVersio