Fibers of calcium alginate produced by a microfluidic device and its mechanical properties

Fibers are important microstructural elements in many foods and calcium alginate fibers may find applications in the structuring of many food analogues. Fiber properties depend largely on their uniform diameter and mechanical properties. The main objective of this research is to production of fibers calcium alginate of regular diameter and to present the effect of concentrations sodium alginate [Alg] and calcium chloride [CaCl2] on the elasticity properties of calcium alginate fibers. The continuous production of calcium alginate fibers with a regular diameter is demonstrated by using a simple microfluidic device (MC). Mechanical properties of fibers were measured using a texturometer and a video camera. The concentrations [Alg] and [CaCl2] varied between 1.25 to 2.5% and 0.5 to 2.5% respectively. Results are presented as function of the tensile stress (σ max) and tensile strain (ΔL/L0) and Young’s modulus (E). For the statistical analysis of the results was used the response surface (RS) method. A mathematical model showed a relationship between mechanical properties as a function of [Alg] and [CaCl2] concentrations. As relevant results, for all [Alg] concentrations first a strengthening and then a weakening of fibers were observed. The tensile stress increased with the [CaCl2] concentration. Maximum fiber tensile stress was found for a [CaCl2] concentration around 1.4%. Opposite to previous works the tensile stress decreased for higher [CaCl2] concentrations. This behavior suggest a model, first “egg-box” sites were filled when the concentration of calcium ions increased up to a saturation point (maximum tensile ≈1.4% [CaCl2]). Then a weakness appeared at higher [CaCl2] concentration, this weakness was not reported in the literature. The tensile strain or percentage elongation at break (ΔL/L0) shown values over 100%. Thus, it is necessary to understand the interaction of cation-polysaccharide-water and to take into account the concentration of sodium alginate and calcium chloride to predict the mechanical behavior of fibers. Alginate gelling properties can be considered as a model system for more complex food materials.