Synergistic interactions of deacetylated konjac glucomannan and fish mince on rheological and textural improvement of newly restructured Malaysian fish sausage (keropok lekor)

The present work investigated the effects of deacetylated konjac glucomannan (KGM) at varying concentrations (3.26, 2.38, and 1.42%) on the rheological, textural, and microstructural properties of keropok lekor restructured with reduced fish mince levels (50, 45, and 40%). Amplitude sweep tests revealed that all KGM-containing samples exhibited higher storage modulus (G’), loss modulus (G”), and critical strain (γcr) values than those of the control (70% fish mince). At 50% fish mince, samples with 3.26 and 2.38% KGM showed the highest γcr (2.54%), whereas samples with 1.42% KGM did not show significant structural improvement. A synergistic effect was observed at 45% fish mince with 3.26% KGM, yielding higher G’ and G” than the 50% fish mince formulation. Dynamic rheological and textural properties showed more significantly enhanced structural formation, particularly at higher fish mince and KGM concentrations. SEM imaging confirmed that higher fish mince levels resulted in more compact gel structures. At 40% fish mince, all formulations with varying KGM levels showed poor structural properties. Overall, KGM acted as effective filler, enhancing viscoelasticity and structure at 45 and 50% fish mince levels, with the 45% fish mince and 3.26% KGM formulation emerging as a promising option for reducing fish content without compromising quality.