Galactomannan-Alginate Synergism Applied in Albumin Encapsulation Francine Valenga, 1,2 Neoli Lucyszyn, 1 Lucy Ono, 3 Clayton F. de Souza, 1 Adriana F. Lubambo, 1,4 Maria Rita Sierakowski * 1 Summary: In this work, the rheological properties of the partial replacement of sodium alginate (AL) by galactomannan extracted from the seeds of L. leucocephala (GML), with or without the presence of calcium ions, were evaluated. The viscoelastic behaviour of polysaccharide blends at 15 gL 1 showed an increase in viscosity when AL was 50% (w/w) replaced by GML. The addition of calcium ions (45 mmol) increased the apparent viscosity of the blend more than 17 times, at a shear rate of 4 s 1 . Micrographs of [GML/AL/ALB] Ca 2þ crosslinked particles obtained by a spraying process were analysed by AFM and revealed spherical forms with diameters in the range of 518 nm, instead of 58.4 nm in the system without albumin. The results of ALB encapsulation (97% w/w) showed that the synergistic mixture GML/AL could be used, in the future, as a new carrier system. Keywords: biopolymers; blends; gels; polysaccharides; rheology Introduction Alginate is a natural unbranched biopoly- mer composed of variable quantities and sequences, depending on the polysacchar- ide source, of 1-4-linked b-D-manuronic acid and a-L-guluronic acid residues. [1] It has been used in various industrial applica- tions as a gelling, thickening and colloidal agent. Soluble sodium alginate can also be crosslinked by divalent cations to produce beads and microspheres, which can be used to encapsulate drugs, proteins and cells. [2–4] The most common technique for this purpose is the atomisation or spraying of the mixture of Na þ -alginate and protein into a divalent crosslinking solution, such as CaCl 2 , using an extrusion device with a small orifice. [1,4] Galactomannans are reserve carbohy- drates found in the endosperm of some legume seeds. This biopolymer is composed of a linear chain of 1!4 linked b-D- mannopyranosil units with D-galactopyra- nosyl units a-(1!6) joined. The galactose distribution at the backbone varies from one botanical source to another and this difference controls properties such as viscosity, solubility, thickening and the stability of solutions. [5,6] For this reason, galactomannans are used as rheology modifiers in food, [7,8] cosmetics, [9] pharma- ceutical products [10] and more recently in biotechnology processes e.g., culturing plant tissue, [11–14] among other applica- tions. It can introduce gel properties to aqueous systems, where it is known to participate in synergistic interactions with other polysaccharides such as xanthan, [15,16] carragennan [17] and agar. [11] Synergistic interactions using galactomannans are of commercial interest because they offer the prospect of generating novel functionality, such as producing rheological or textural characteristics by using reduced levels of Macromol. Symp. 2011, 299/300, 99–106 DOI: 10.1002/masy.200900096 99 1 Laboratory of Biopolymers, Department of Chem- istry, Federal University of Parana ´ (UFPR), PO Box 19081, 81531 - 990, Curitiba, PR, Brazil Fax: (þ55) 41 33613186; E-mail: mariarita.sierakowski@ufpr.br 2 Department of Biochemistry and Molecular Biology, UFPR, Curitiba, PR, Brazil 3 Department of Basic Pathology, UFPR, Curitiba, PR, Brazil 4 Department of Physics, UFPR, Curitiba, PR, Brazil Copyright ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com