Thermal and optical properties of mixed pectin-wax films

BAÜMLER, ERICA; CARELLI, AMALIA; MARTINI, SILVANA

Cincinnati, Ohio

Congreso; The AOCS Annual Meeting & Expo; 2011

American Oil Chemists’ Society

Edible films are generally made from proteins, polysaccharides and lipids, used alone or together. The use of pectin has been proposed because it is edible and gives an attractive coating. Improved films are obtained with a multicomponent system where hydrocolloids form a continuous and cohesive network, and the hydrophobic substances provide the moisture barrier properties. The objective of this research was to develop composite biofilms produced using mixtures of low-methoxyl pectin and sunflower waxes, this material was included in film formulation in order to increase the water impermeability. Physical, thermal and optical properties were characterized. The film thickness, determined with a manual micrometer, showed an increment as the concentration of pectin increased. The measurement was influenced by the surface roughness. Polarized micrographs of the films showed marked differences in their microstructure. The addition of waxes caused a whitish color, a rough surface film and a light transmission reduction. Two melting endothermic peaks were observed by differential scanning calorimetry: The peak at 70-80°C region was assigned to the melting of waxes, while the other one was observed at temperatures above 100°C and belonged to moisture removal. The increase of pectin content caused a decrease in the waxes melting enthalpy; this might be caused by the inhibition of the growth of the wax crystals provoked by the pectin emulsifier effect. Key words: low- methoxyl pectin, sunflower waxes, biofilms