Mechanical stability of carrageenan and carrageenan/locust bean gum gels used for immobilization of propionic acid bacteria
Mechanical properties of 1, 2 and 3% carageenan and 1, 2 and 3% carrageenan/locust bean gum (Lbg) gels stored in propionic and acetic acid solutions and its mixtures were examined. Stability of these materials was measured by uniaxial compression between two parallel plates using Instron Universal Testing Machine model 1140. The relationship between force and energy in destroying the gel sample was linear. Mathematical model explaining the dependence of destroying force on storage time was choosen for data analysis. Using this model the avarage rate of gel deterioration was calculated. Structural properties of examined gels were the most influenced by the highest concentration of propionic and acetic acid and its mixtures (1% acetic acid and 2% propionic acid). The addition of Lbg to carrageenan decreased the gel destroying force, and increased its resistance to acids.