Porous hydrogel composite with whey protein isolate and galactomannans of Leucaena leucocephala (subabul) seeds: Stability, rheological, thermal, and morphological characterization

The present study was aimed at curating a porous KCl crosslinked hydrogel with purified subabul galactomannans (SG) from the defatted seeds of Leucaena leucocephala (subabul) and κ-carrageenan (κC) by inducing whey protein isolate (WPI). WPI showed 345% foam overrun and minimal foam drainage (%) at 70°C when whipped for 5 min at pH 6.8 in the hydrogel prepared with 6.5% w/v SG + 1% w/v κC + 0.63% w/v KCl + 2% w/v WPI. The SG and WPI incorporated porous hydrogel (SGWP) showed maximum G' (3010 Pa) and frequency independence (>30 Hz) at 65°C. NMR (1 H), scanning electron microscopy, and thermal characterization of SGWP showed a crosslinked microporous gel network formation. SGWP had high water uptake rate (Q) (432%) at 45°C. The stability of SGWP at neutral pH and high temperature (65°C) added an impetus to this study as it could be used for a wide range of applications. Hence the protein-polysaccharide complexation improvised the functional properties of the porous hydrogels. The results suggested a possible valorization of galactomannans from subabul, a forest resource, into a porous hydrogel suitable as a matrix for delivery of bioactive(s) or an aerogel for multifarious industrial applications. PRACTICAL APPLICATION: A porous hydrogel is defined as a solid, or collection of solid bodies, with sufficient open space to enable a fluid to pass through or around them. Leucaena leucocephala seed (forest resource) galactomannans are non-starch polysaccharides having weak gelling capacity. Whey protein isolates (WPI) are a dairy industry byproduct having excellent foaming properties. Incorporation of WPI in the hydrogel prepared with subabul galactomannan and κ-carrageenan using KCl as a crosslin could form a stable porous structure having high water uptake rate (Q) at neutral pH and elevated temperature. The hydrogel so developed could be a step toward circular economy.