Pullulan, a plant-based gelling agent, was used as the main gelling agent for soft capsule shells. The production process of soft capsules using pullulan as the main gelling agent was investigated, and soft capsules using gelatin as the shell gelling agent were compared in terms of disintegration time, oil leakage, content oxidation, and adhesion. The results showed that soft capsules using pullulan as the main gelling agent exhibited better disintegration time, content oxidation, adhesion, and oil leakage after a period of storage compared to soft capsules using gelatin.
Pululan-carrageenan was used as the main component of the gelling solution. The effects of the component ratio on the oil permeability, tensile strength, elongation at break, gel strength, and light transmittance of the capsule shell were explored, thus determining the preparation method for soft capsules. The optimal formulation of pullulan-carrageenan soft capsule shells was determined through response surface methodology based on single-factor experiments. The optimal preparation scheme was obtained: carrageenan content 1.25% (compound gel ratio 23.5:2.5), fructose content 4.7%, and potassium ion content 0.11%. Under this scheme, the tensile strength, elongation at break, and gel strength were (34.6875±1.6253) MPa, (50.1346%±2.6834%), and (463±13) g/cm², respectively. The experimental results are in good agreement with the theoretical values. The results obtained from the response surface methodology optimization have certain guiding significance for practical production and further research.
