Mathematical model of Ca 2+ concentration, pH, pectin concentration and soluble solids (sucrose) on the gelation of low methoxyl pectin

A systematic study was made of the gelation of low methoxyl pectin (LMP) using mathematical models of the effects of pH, and Ca2+, sucrose, and pectin concentrations. When [Ca2+] was 16–88 mg/g, the mathematical model of gel strength (analyzed by texture analyzer) applied a DoseResp function, which showed a trend similar to that of a microbial growth curve. The function between gel strength and pH conformed to a polynomial that showed maximum gel strength at pH 3.5. For pH 3.5–5.0, the gels were stable because calcium bridges formed with galacturonic acid residues. Near the isoelectric point (3.50), increased [Ca2+] enhanced the storage modulus (G′) and gel strength by formation of Ca-bridges at dissociated carboxyl groups. The mathematical model for gel strength and pectin molecule was a BiDoseResp function and suggested that more pectin provided more hydrophobic interactions and cross-linking junctions between the pectin chains. Sucrose content promoted the gel strength because sucrose provided more hydroxyl groups to stabilize the junction zones and promote hydrogen bonds to immobilize free water. These findings suggest that the mathematical models and their combination will be useful in a range of food and biomedical applications that require different gel strengths.