Molecular structural modification of jack bean protein using thermo-shearing/ultrasound/microwave treatments for improved extractability, functional and gelling properties: The underlying impacts of matrix pre-treatment versus alkaline-assisted extraction.

Inspired by the exploration of underutilized legumes for addressing the existing and long-term food security challenges, jack bean protein (JBP) was investigated. Different mechanical treatments (thermo-shearing, ultrasound, and microwave treatments) before (pre-treatment) and after alkaline aqueous dispersion (assisted-alkaline treatment) were employed to extract JBP. We hypothesize that these extraction treatments received by JBP will present different effect on the structure and techno-functional properties. In this study, changes in the molecular structure, functional, and gelling properties of JBP subjected to mechanical treatments were comprehensively investigated. Results showed that microwave assisted-alkaline extraction (ME) exhibited the highest protein content (86.34 %). Electrophoretic patterns suggested that ultrasound pre-treatment (UP) and ultrasound assisted-alkaline extraction (UE) did not cause any degradation of JBP components. Microscopic images of JBP showed that assisted-extraction treatment promoted larger fragments and internal pores compared to matrix pre-treatment. FTIR analysis revealed that mechanical treatments decreased β-sheet and α-helix structures of JBP. UP and UE treatments showed an increase in the sulfhydryl, and disulfide contents of JBP. For the functional properties, ME treatment showed significantly improved solubility, emulsifying and foaming capacities, water-holding and oil-holding capacities when compared to other treatments. ME treatment also increased both the energy storage (G’) and energy loss modulus (G″) of JBP suspensions and enhanced the “visco-elastic” solid behavior of the protein suspension. In summary, exploring different mechanical treatments prior to and after alkaline dispersion of jack bean flour has generated knowledge for the extraction of JBP and its utilization as a new protein ingredient.