Structural properties of cottonii seaweed (Kappaphycus alvarezii) gels in the presence of coconut milk

In this study, Indonesian dried cottonii seaweed was evaluated for the physicochemical and gelation properties. The non-starch polysaccharide is mainly composed of galactose (∼21% w/w) with sulfate groups as the functional group. The effect of salt types (KCl, CaCl₂, NaCl) and also coconut milk (CM) with different concentrations (0, 0.25, 0.5 and 1.0% w/w) on the gel textural and rheological properties of seaweed gels were investigated. The results revealed that addition of KCl formed the strongest and most cohesive gel network due to it was able to promote the formation of adjacent double helixes of κ-carrageenan through electrostatic interactions of two adjacent sulfate groups. Addition of CM appeared to enhance the gel elastic and gel temperature properties during cooling from 96 to 5 °C, with 0.25% w/w as the optimum concentration. More importantly, the gel syneresis reduced significantly (p < 0.05) with CM incorporation. The gel microstructure indicated that the gel network was more compact in the presence of CM, which further verified the increase in gel elasticity. This study suggests that combination of KCl and CM have potential applications in development cottonii-seaweed pudding gels.