Modulation in the rheological behaviour of porcine pepsin treated guar galactomannan on admixture with κ-carrageenan.

The non-specific action of pepsin on guar galactomannan (GG) resulted in selective removal of galactose residues, leading to the formation of galactose - depleted guar galactomannan (GDGG) with decrease in Mw and change in G: M ratio of 1:3.4, thus mimicking that of locust bean gum (LBG). Admixture of GDGG with κ-carrageenan revealed a two fold increase in the magnitude of elasticity (G') compared to κ-carrageenan alone, suggesting a synergistic interaction similar to LBG with κ-carrageenan. Blends of GDGG and LBG with κ-carrageenan at a concentration of 40% (w/w, 0.8% total biopolymer) showed a maximum increase in G'. The GDGG/κ-carrageenan blend also showed a Tm of 47°C, similar to LBG/κ-carrageenan blend. Thus, debranching of guar galactomannan by the catalytic action of pepsin is beneficial for improved functional properties and diversified applications.