A possible rheological model of gum candies

Abstract

An appropriate rheological model can be used in production of good quality gum candy required by consumers. For this purpose Creep-Recovery Test (CRT) curves were recorded with a Stable Micro System TA.XT-2 precision texture analyser with 75 mm diameter cylinder probe on gum candies purchased from the local market. The deformation speed was 0.2 mm s -1 , the creeping-and recovering time was 60 s, while the loading force was set to 1 N, 2 N, 5 N, 7 N, and 10 N. The two-element Kelvin-Voigt-model, a three-element model, and the four-element Burgers-model were fi tted on the recorded creep data, and then the parameters of the models were evaluated. The best fi tting from the used models was given by the Burgers model. Keywords: Burgers model, gum candy, rheological modelling, texture analyserThe quality of foods can be described by both sensory and physical properties (SZCZESNIAK, 2001). The texture and its change can be characterized by rheological parameters: LAMBERT-MERETEI and co-workers (2010) evaluated the changes of hardness, chewiness, gumminess, cohesiveness, and springiness of bread crumb after addition of bread improver. co-workers (2008, 2011) determined the deformation work and stiffness of carrot texture during non-ideal storage. From consumer's view the main quality properties of gum candies are also textural properties. From the producer's view, the quality and the texture of gum candy has to be described by such rheological test that is objective and models the chewing process. The gum candy is sucrose based, combined semisolid gel, which contains approximately 10% gelatine. The sugar content (sucrose, glucose syrup, and dextrose in certain proportion) ensures the required texture profi le, while the gelatine secures the typical viscoelastic rheological behaviour (MOHOS, 1993). The origin, the quality, and the quantity of applied gelatine determine the main quality and sensory properties of candy (MOHOS, 2010).According to MITCHELL'S (1980) comprehensive study of gel rheology, the majority of food material gels show linear viscoelastic behaviour up to strain of 0.1 range. If the strain is higher than 0.1, the creep and the stress relaxation of gels would suggest the move and the brake of non-covalent cross links under stress.The gelatine is a biopolymer protein, obtained by hydrolytic degradation of collagen. Native conformation of collagen is a triple helix held together by inter-chain hydrogen bonding. Above 37 °C in aqueous solutions the gelatine molecules exist as separate, disordered chains (coils). When a solution containing around 1% w/w gelatine is cooled to room temperature, the gelatine molecules form an infi nite network cross-linked by hydrogen bonding (MARFIL et al., 2012). The role of the coil-helix transition in this mechanism has

Perga under compressive loading

“…Severa (2008) interested with the compression test of the fruits at the different strain rates which corresponded to the quasi -state loading. If the material exhibits viscoelastic behavior a Maxwell model with increasing modulus of elasticity can be considered as a simple so called explanatory model, which can explain the stress -strain curves (Csima et al, 2014). Jambrec et al, (2015) applied compression test attachments by measuring textural properties of differently formulated commercial tagliatelle samples with TA.XT Plus texture analyser equipped with Ottawa and Mini Kramer cell.…”