Optimizing Rheological Behavior of Pectin Gels: A Response Surface Methodology Approach

Abstract

Pectin, a natural polysaccharide widely used in the food and pharmaceutical industries, forms gels in the presence of sugar and divalent ions such as calcium. Its rheological behavior is strongly influenced by extrinsic factors including pH, calcium chloride, and sugar concentration. This study aimed to optimize the viscosity of pectin gels prepared in aqueous medium, targeting applications in edible films and biodegradable packaging. Gel formulations were prepared with varying calcium chloride concentrations (5-15% w/v), pH levels (4.5-8.0), and sugar concentrations (5-20% w/v). Viscosity was measured using a Brookfield viscometer and analyzed by response surface methodology (RSM). Results showed that pH had the strongest effect, with viscosity increasing from 1734.2 cP at pH 4.5 to a maximum of 2681.2 cP at pH 8.0, reflecting enhanced ionization and cross-linking. Calcium chloride exhibited an optimum at 10% w/v (1097.6 cP), while sugar enhanced viscosity up to 15 g (2747.2 cP) but declined at higher levels due to excessive dehydration. ANOVA confirmed the model’s significance (p < 0.001), with strong quadratic effects but negligible interactions among factors. Optimal viscosity was obtained under near-neutral pH, 10% w/v calcium chloride, and 15% w/v sugar, highlighting the potential of pectin gels as sustainable biomaterials for food and pharmaceutical applications.