Deformation and fracture behavior of physical gelatin gel systems

MARINA CZENER; LAURA A. FASCE; JOSEFA MARTUCCI; ROXANA RUSEKAITE; PATRICIA M 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 andmechanically similar to many gel-like food products. In this paper, eight gelatin gel systems withdifferent 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 behaviorwas evaluated and the mechanical response was characterized through puncture tests, uniaxialcompression experiments and wire cutting fracture tests. From these tests, apparent gel strength, firstorder 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 isshown 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. Thefound experimental trends suggest that in the quasi-static range the overall mechanical behavior ofgelatin gel systems is mainly controlled by the initial shear modulus, which is a direct measure of gelstiffness.© 2016 Published by Elsevier Ltd.1. Introduction