Structural modification of plum (Prunus domestica L) kernel protein isolate by supercritical carbon-dioxide treatment: Functional properties and in-vitro protein digestibility

The effect of supercritical carbon dioxide (SC-CO2) treatment at different processing temperatures (30-70 degrees C) on the physico-functional properties, structural features, and in-vitro digestibility (IVPD) of plum kernel protein isolates (PKPI) was examined. The results revealed remarkable changes in the secondary structures of SC-CO2- treated PKPIs, including a decrease in alpha-helix proportion, a concomitant increase in beta-sheet content, and a considerable variation in random coils and beta-turn structures. The temperature rise increased the negative zeta potential to a maximum of 31.35 mV at 60 degrees C, exhibiting the colloidal stability of PKPI dispersions. SDS-PAGE analysis showed variations in the intensities of protein bands, indicating denaturation and aggregation at higher temperatures. These structural and molecular changes improved water-binding capacity (1.22-fold) and oil binding capacity (1.11-fold), wettability (1.12-fold), and the highest value in all the properties was recorded at 60 degrees C. Moreover, the highest IVPD value (21.58 %) and a distinguishable colour difference (Delta E) of 8.11 was also obtained at 60 degrees C of the processing temperature. Therefore, SC-CO2 treatment-induced modification of PKPI contributed to the enhanced digestibility and techno-functional properties, which offered new prospects to extend its use in food applications.