Effect of ε-polylysine addition on κ-carrageenan gel properties: Rheology, water mobility, thermal stability and microstructure

Abstract

Kappa-carrageenan is a gel forming anionic sulfated polysaccharide used extensively in food applications. Metal ions, proteins and other polysaccharides influence its gelation. Though polypeptides are known widely for their intrinsic benefits in developing healthy food products, their effect on κ-carrageenan functional properties has not been established yet. Herein, influence of ε-polylysine (0.05, 0.1, 0.15, 0.2 and 0.3%, w/v) on the viscoelastic and thermal properties, water mobility and microstructure of κ-carrageenan gels has been carried out. The storage modulus, gel-sol transition temperature and thermal stability increase with the ε-polylysine addition along with a decrease in the water mobility. The shift in the FT-IR absorption bands of the sulfate groups coupled with the disappeared Amide II clearly accentuate the synergistic interactions between κ-carrageenan and ε-polylysine. Such changes reflect on the more regular microstructure with compact cavities filled with the polypeptide. Overall, ε-polylysine exerts favorable interaction mechanisms on the κ-carrageenan gels. The outcome has potential to open up novel research opportunities on the binary mixtures of polysaccharides and polypeptides toward developing new and healthy food products with suitable organoleptic properties for the growing population.