Large deformation mechanical behavior of gelatin–maltodextrin composite gels

Abstract

ABSTRACT:The large deformation failure behavior of gelatin-maltodextrin composite gels was assessed. All the studied compositions were selected to lie within the incompatibility domain of the gelatin-maltodextrin phase diagram at 60°C, which produced gelatin continuous (maltodextrin included) and maltodextrin continuous (gelatin included) composites. Composite microstructural evaluation was performed using confocal laser scanning microscopy (CLSM). The large deformation mechanical behavior was measured in tension and compression experiments. Crack-microstructure interactions were investigated by dynamic experiments on the CLSM. The gelatin continuous composites exhibited pseudo-yielding behavior during tension and compression testing, and there was a significant decrease in modulus that arose from interfacial debonding. Conversely, the maltodextrin continuous composites exhibited an essentially brittle failure behavior, and there was an approximately linear increase in stress with increasing strain until fracture (which occurred at significantly lower strains than for the gelatin continuous composites). The CLSM observation of the failure of the notched samples also demonstrated interfacial debonding in the crack path; however, this occurred at significantly smaller strains than for the gelatin continuous samples with minimal elastic-plastic deformation of the maltodextrin matrix. The Poisson ratio was estimated to be close to 0.5 for these composites for all examined compositions. Compositions corresponding to a tie line of the phase diagram were also investigated to assess the influence of the relative phase volume (for constant phase compositions) on the failure behavior. The majority of the parameters subsequently extracted from the stress-strain curves were apparently functions of the individual phase volumes.

Influence of thermal history on the structural and mechanical properties of agarose gels

“…Gelation is seen to precede the large increase in turbidity, clearly showing that the demixing process leading to the formation of micron size domains occurs in the gel state. This is a rather unexpected finding, as in most biopolymer mixtures, gelation usually traps phase separation by freezing fluctuations of concentration 35, 52, 53…”

The Effect of Composition, Pre-Treatment on the Mechanical and Acoustic Properties of Apple Gels and Freeze-Dried Materials

“…Some investigations have shown that the concentration of maltodextrin above 20% resulted in the formation of stronger gels [ 34 , 35 ]. The gelatin-maltodextrin composite gels exhibited a brittle failure behaviour which occurred at a lower strain than observed for the gelatin gels [ 36 ]. The presence of nuclei (aggregates of double helices of amylose) in maltodextrin gels created larger number of crystallites, which led to the rapid formation of a stronger gel.…”

Temperature influences on network formation of low DE maltodextrin gels

“…When included in a mixed gel system, unique fat-like properties have been observed (Chronakis, 1998). Surrounding this effect, many studies have focused on maltodextrin mixed gels with gelatin (Brown, Foster, Norton, & Underdown, 1995;Butler & Heppenstall-Butler, 2003;Kasapis, Morris, Norton, & Brown, 1993;Kasapis, Morris, Norton, & Clark, 1993b;Lorn & Hermansson, 2000;Lundin et al, 2000;Nickerson et al, 2006;Normand, Plucknett, Pomfret, Ferdinando, & Norton, 2001), pectin (Picout, Richardson, & Morris, 2000), and agarose (Loret, Frith, & Fryer, 2006). Several patents have even been granted utilizing the unique creaminess of maltodextrin-gelatin mixed gel system for reduced fat food products (Cain et al, 1990;Wesdorp, Madsen, Norton, & Brown, 1995).…”