Effect of starch source on gel properties of kappa-carrageenan-starch dispersions

• Introducing of starch increased gel strength of carrageenan dispersions.
• Starch effect was more profound at carrageenan concentration below 1%.
• Carrageenan-starch dispersions showed lower syneresis than that of carrageenan alone.
• Starch with high granular rigidity had more profound effect on gel strength and syneresis.

Eight different starches (2%, w/w) were incorporated into dispersions containing various amount of kappa-carrageenan (0.2%, 0.6% and 1.0%, w/w), and the properties including morphology, rheology, texture and syneresis of gel from carrageenan and carrageenan-starch dispersions were examined and compared for elucidating the effect of starch source on gel properties of the dispersions. Results showed that the swelling of starch granules in carrageenan dispersions decreased with increasing concentration of carrageenan. Carrageenan dispersions incorporated with starch possessed high granule rigidity or low swelling power had high values of storage modulus and gel firmness. The presence of starch reduced the syneresis of carrageenan gels, and this was more profound for dispersions containing starch with high amylose content. At each concentration of carrageenan, swelling power of starch showed significant correlations with the storage modulus (r2 ≥ 0.590, p < 0.05) and firmness (r2 ≥ 0.890, p < 0.05) of carrageenan-starch dispersions. Results indicate that the presence of starch in carrageenan dispersion improves the gel strength and reduces the syneresis of carrageenan. Moreover, the amylose content of starch and the rigidity of gelatinized starch granules play important roles on gel properties of carrageenan-starch dispersions.

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