Geles de gelatina. Sistemas modelos para alimentos

M. CZERNER; M. PRUDENTE; J.F. MARTUCCI; L.A. FASCE

Congreso; VI Congreso Internacional de Ciencia y Tecnología de Alimentos (CICYTAC 2016); 2016

Gelatin gel systems with different stiffness were prepared by varying gelatinconcentration (10-30 %w/w), collagen source (bovine/porcine) and solvent composition (0/40%w/w glycerol/buffer mixture). In addition, hybrid gels were prepared by first chemical crosslinking gelatin with BDDGE and then promoting physical entlaglements.The swelling behavior was evaluated and the mechanical response was characterized through puncture tests, uniaxial compression experiments and wire cutting fracture tests. From these tests, apparent gel strength, first order Ogden constitutive parameters (shear modulus, m, and strain hardening capability, a) and fracture toughness (Gc) were determined. Physical gel samples that display apparent gel strength and swelling behavior consistent with a more physically cross-linked structure exhibit larger m and Gc and lower a values. It is shown that a and Gc are related with m independently of gelatin concentration, collagen source and glycerol presence. a decreases exponentially with increasing m whereas Gc increases linearly with m. The found experimental trends suggest that in the quasi-static range the overall mechanical behavior of physical gelatin gel systems is mainly controlled by the initial shear modulus, which is a direct measure of gel stiffness. Hybrid gels exhibit a shear modulus of the order of physical gels with the same concentration but a larger strainhardening capability.