Insight of pH-shifting as an effective pretreatment to reduce the antigenicity of lectin from red kidney bean (Phaseolus vulgaris L.) combining with autoclaving treatments: The structure investigation.

• pH-shifting was effective in reducing lectin allergy combining with autoclaving. • More hydrophobic exposures were confirmed in refolding process of pH-shifting. • β-turn increased and random coil decreased after the combining treatment. • Lectin aggregation was observed after autoclaving and enhanced with low pH treated. • Flexible structure and exposure of enzyme cutting sites improved digestibility. Combined effects of pH-shifting and an autoclaving cycle (121 °C, 15 min) on red kidney bean lectin (RKBL) were investigated using intrinsic and extrinsic fluorescence, UV, FTIR, DSC, SEC, dot-blot analysis and in vitro digestibility. Spectroscopic studies suggested that the protein refolding was stable after 3 h incubation with the hydrophobic exposure after pH-shifting, and hydrophobicity was significantly increased with the formation of more looser structure, which would influence the structural stability of known epitopes. In details, the increase of β-turn and reduction of random coil was related with the lower denaturation enthalpy, while the protein aggregation was also observed in acidic treated samples after autoclaving. Lower antigenicity and good digestibility suggested the exposure of enzyme cutting sites, and confirmed the effectivity of pH-shifting prior to the autoclaving. Then the results would be beneficial to the development of hypoallergenic kidney bean foods. [ABSTRACT FROM AUTHOR]