Physical characteristics of agar-yeast sponges

Agar-yeast sponges were produced by entrapping yeast within agar gels and immersing them in a 5% sucrose solution for 3 and 7 days. All gels were freeze-dried and kept over silica gel to avoid rehydration prior to testing and their mechanical properties were studied. The resultant cellular solids were compressed to ∼80% deformation between parallel lubricated plates and the stress-strain relationships were fitted to a compressibility model previously developed for the sigmoid stress-strain relationships of cellular solids: σ = C₁ε/[(1 + C₂ε) (C₃ - ε) ], where σ and ε are the stress and strain, respectively, and C₁, C₂ and C₃, are constants. The sponges' inner structure was studied by scanning electron microscopy. Sensory evaluation, color measurements and the enrichment of such sponges with embedded dry yeasts suggest the possibility of their use as a future food and carrier of proteins, carbohydrates, vitamins and minerals.