Electrospinning of Guar Gum/Corn Starch Blends

Abstract

Open Access Research Articlesuccess of electrospinning will rely on the proper optimization of several process parameters including flow rate of spinning solution, applied voltage and distance from the needle tip to the fiber collector, as well as relevant solution properties such as viscosity, viscoelasticity, concentration, electrical conductivity and surface tension [6,14,28].Food-grade hydrocolloids of commercial importance include polysaccharides (natural carbohydrate polymers) and proteins. Food-grade hydrocolloids, alone or combined, are widely used by the food industry to improve texture, processing conditions and the overall quality of food products [3,17]. Processing hydrocolloids by electrospinning is often challenging since most of these compounds show inadequate or limited spinnability [28].Starch and guar gum are two cost-attractive hydrocolloids often used together in food formulations [8]. Starch is present in plants as semi crystalline granules which shape, size, morphology and composition (e.g. amylose/amylopectin ratio) will depend on the starch source and cultivation conditions [3,13]. The granules are composed of amylose or (1→4)-linked α-glucopyranose, a linear macromolecule responsible for starch's gelling properties [18], and amylopectin or (1→4)-linked α-glucopyranose with α-(1→6) branch linkages, a highly branched component that may form very weak gels [20]. Guar Gum (GG) is extracted from Cyampsis tetragonolobus seeds [32] and is formed by linear chains of β-(1-4)-D-mannan with side units of α-(1-6) linked galactose [24].Electrospinning of starch and GG have been studied separately in a few papers. Lubambo et al. [16] found that fibers obtained from GG solutions were not uniform and had insoluble aggregates between fibers and within their structure. These authors concluded that sequential filtration steps were needed after GG purification to reduce the aggregates and improve fiber morphology. Pure starch fibers in turn, could only be obtained from Dimethyl Sulfoxide (DMSO) solutions using electro-wetspinning technology due to the non-volatile nature of the organic solvent [12,13]. Starch derivatives have also been electrospun from formic acid solutions [15,34] while composite fibers have been produced from blends of starch with non-food grade polymers such as polyvinyl alcohol [29] and polylactic acid [30]. AbstractIn this study, electrospun nanofibers were prepared for the first time, from aqueous blends of guar gum (GG) and corn starch with amylose contents of 27.8% (CS28) and 50% (CS50). The fiber morphology and fiber diameter sizes (FDS) were correlated with solution rheology. The spinning solutions were prepared with 3 wt% total concentration and mass ratios ranging from 4:1 to 1:4 GG/CS. The GG alone (3 wt%) was highly viscous and predominantly elastic (G'>G'') over the range of tested frequencies. Both CS were effective rheological modifiers that facilitated the electrospinning process. Partial substitution of GG by CS decreased solution viscosity and moved the elastic plateau (...

Fabrication of Guar-Only Electrospun Nanofibers by Exploiting a High- and Low-Molecular Weight Blend

“…27−30 To overcome some of these limitations, biopolymers are often blended with a synthetic polymer which has more flexible chains and can induce a degree of elasticity in the blended solution so that fibers can stretch without breaking up into droplets. 29−33 Some groups have also reported electrospinning of blends of gums such as tragacanth and almond gum with various polymers for the ease of electrospinnability. 34−37 Nevertheless, the presence of a synthetic polymer in the fiber mat limits its efficacy in the applications that require the presence of pure biopolymers.…”

“…They attributed the unsuccessful fiber formation of these gums to either a low zero-shear viscosity or, in the case of high zero-shear viscosity, a strong shear thinning behavior. Notably, biopolymers tend to be very rigid molecules in their native states, and their stiffness proves to be problematic when bending and stretching of the solution jet occur during electrospinning. − To overcome some of these limitations, biopolymers are often blended with a synthetic polymer which has more flexible chains and can induce a degree of elasticity in the blended solution so that fibers can stretch without breaking up into droplets. − Some groups have also reported electrospinning of blends of gums such as tragacanth and almond gum with various polymers for the ease of electrospinnability. − Nevertheless, the presence of a synthetic polymer in the fiber mat limits its efficacy in the applications that require the presence of pure biopolymers.…”