Deformation and fracture behavior of physical gelatin gel systems

M. CZERNER; L. FASCE; J. MARTUCCI; R. RUSECKAITE; P. FRONTINI

FOOD HYDROCOLLOIDS

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2016 vol. 60 p. 299 - 307

0268-005X

Food scientists usually used biopolymer physical gels as model systems because they are structurally and mechanically similar to many gel-like food products. In this paper, eight gelatin gel systems with different stiffness were prepared by varying gelatin concentration (10e30%w/w), collagen source (bovine/porcine) and solvent composition (0/40%w/w glycerol/buffer mixture). 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 fracturetoughness (Gc) were determined. Samples that display apparent gel strength and swelling behaviorconsistent 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 andglycerol 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 gelatin gel systems is mainly controlled by the initial shear modulus, which is a direct measure of gelstiffness.