title: Mechanical properties of calcium alginate fibers produced with a microfluidic device.
abstract: Fibers are important microstructural elements in many foods. The main objective of this research was to produce calcium alginate fibers with uniform diameters (about 300 and 550 μm) using a microfluidic device (MFD) and to study the effect of concentration of sodium alginate [Alg] and calcium chloride [CaCl2] on their mechanical properties (MP). Moisture content (MO) and MP as maximum tensile stress (σmax), tensile strain at break (ΔL/L0) and apparent Young's modulus (E) of fibers were determined and a statistical model and surface responses were developed as a function of [Alg] and [CaCl2]. As [CaCl2] increased first a strengthening and then a weakening of fibers were observed. Furthermore, σmax increased with the addition of Ca(2+) and a maximum of σmax was obtained for a [CaCl2] around 1.4% (exceeding several times the stoichiometric requirements of the carboxylate groups of the polymer). Such behavior prompted a molecular explanation of what happens during gelation based on the "egg-box model" and this model is tried to complete. Moreover, fibers with [Alg] ≥1.8% showed high extensibility (ΔL/L0 around 100%) and low values of MO. High values of E (∼0.5 MPa) were obtained for [CaCl2] close to 1.4%. A greater understanding is needed of the interaction between cation-polysaccharide-water, taking into account [Alg] and [CaCl2] to predict the mechanical behavior of fibers. Calcium alginate fibers are important in food engineering as texture and microencapsulation agents.
authors.affiliation: Pontiﬁcia Universidad Católica de Chile, School of Engineering, Department of Chemical and Bioprocess Engineering, P.O. Box 306, Santiago 22, Chile.
authors.forename: Teresa R
authors.initials: TR
authors.lastname: Cuadros
authors.affiliation: Universidad Técnica Federico Santa María, Department of Mechanical Engineering, Av. Vicuña Mackenna 3939, Santiago, Chile.
authors.forename: Olivier
authors.initials: O
authors.lastname: Skurtys
authors.affiliation: Pontiﬁcia Universidad Católica de Chile, School of Engineering, Department of Chemical and Bioprocess Engineering, P.O. Box 306, Santiago 22, Chile.
authors.forename: José M
authors.initials: JM
authors.lastname: Aguilera
mesh_terms: D000464:Alginates / Q000737:chemistry*; D004043:Dietary Fiber; D055119:Elastic Modulus; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D046210:Microfluidic Analytical Techniques / Q000379:methods*
chemical_list: D000464:Alginates; D004043:Dietary Fiber; D006603:Hexuronic Acids; D020723:Glucuronic Acid