Gel Properties of Low-Methoxyl Pectin-Sodium Alginate Composite Gel Systems

Composite gel network systems were prepared by mixing sodium alginate (ALG) with low methoxyl pectin (LMP) with the addition of Ca²⁺. The effect of different LMP/ALG ratios and Ca²⁺ concentrations on gel properties including gel strength, moisture state and gel network structure was investigated. At an LMP/ALG ratio of 3:7, the largest gel strength of 0.545 N. The gel strength increased with the increase in Ca²⁺ concentration, and the gel network showed a dense microstructure with small pores. The rheological properties of the composite gels were analyzed based on three strain models, revealing that the two polysaccharides formed an interpenetrating network in the composite gel system. This study provides a scientific reference and theoretical basis for improving the gel properties of ALG and LMP and for expanding their applications in foods.