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Effect of glycerol and Ca+2 addition on physicochemical properties of edible carrageenan/porphyran-based films obtained from the red alga, Pyropia columbina
- Cian, Raúl E., Salgado, Pablo R., Drago, Silvina R., Mauri, Adriana N.
- Journal of applied phycology 2015 v.27 no.4 pp. 1699-1708
- Rhodophyta, additives, calcium, carrageenan, dispersions, glycerol, materials, modulus of elasticity, permeability, plasticizers, tensile strength, water content, water solubility, water vapor
- Our aim was to study the effect of glycerol and Ca⁺² addition on physicochemical properties of phycocolloid (carrageenans/porphyrans)-based films obtained from Pyropia columbina aqueous fraction. Films were formed by casting from aqueous dispersions of phycocolloid-enriched fraction (P) with different levels of glycerol (0, 12.5, and 25 g (100 g)⁻¹ dry solid) and the optional addition of Ca⁺² (16 g (100 g)⁻¹ dry solid), yielding six formulations according to a multi-factorial design (P, PG₁, PG₂, PCa, PCaG₁, and PCaG₂). All films were homogeneous, flexible, and slightly greenish. Moisture content, water solubility, and water vapor permeability of films were significantly increased by adding glycerol to the formulation (11, 12, and 6 %). Increasing glycerol content in formulations (12.5 to 25 g (100 g)⁻¹ dry solid) allows obtaining more stretchable but less resistant films (with less tensile strength and elastic modulus) than those produced without plasticizer (P). Ca⁺² addition masked glycerol effect in some properties (water solubility and water vapor permeability), but in others, the effect of Ca⁺² was added to the plasticizer glycerol effect (mechanical properties). Ca⁺² could stabilize the three-dimensional structure of P phycocolloids by interactions between sulfate groups, promote water retention, and open film structure. Use of these additives yielded films from P. columbina with a wide range of mechanical properties, thus extending the scope of these materials.