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Dried Ca-alginate films: Effects of glycerol, relative humidity, soy fibers, and carrageenan

Barbut, Shai, Harper, B. Allison
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2019 v.103 pp. 260-265
calcium alginate, cellulose, chaff, composite films, composite materials, glycerol, kappa carrageenan, optical properties, relative humidity, soybeans
Dried Ca-alginate and Ca-alginate composite films made with cellulose extracted from soybean chaff or κ-carrageenan were conditioned at 57% or 100% relative humidity (RH) and their mechanical and optical properties compared. Additionally, the effect of adding glycerol to the films was explored. Alginate-cellulose films required less force (30%), distance (35%) and work to puncture (40%) than pure alginate films conditioned at the same RH. The alginate-cellulose films were also the least transparent of the films conditioned at 100% RH. Contrarily, adding κ-carrageenan had little effect on the mechanical or optical properties of the dried films. Films conditioned at 57% RH required greater force (on average + 20%) but showed less distance to puncture (average 25%) than their counterparts conditioned at 100% RH. With the exception of the pure alginate films made without glycerol, all of the films conditioned at 100% RH had higher elongation values than their corresponding films conditioned at 57% RH. Dried films conditioned at 100% RH were also more transparent than those conditioned at 57% RH. Glycerol did not induce many differences in the mechanical and optical properties of films.