Amaranth protein films from thermally treated proteins

• Published in: Journal of food engineering 2013-12, Vol.119 (3), p.573-579
• Main Authors: Condés, María Cecilia, Añón, María Cristina, Mauri, Adriana Noemí
• Format: Article
• Language: English
• Subjects: Amaranth; Amaranth proteins; Crosslinking; Mechanical properties; Peptides; Plasticizers; Polypeptides; Protein cross-linking; Protein films; Proteins; Stabilization; Thermal treatment; Water vapor
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2013.06.006

•Heat treatment at 70 and 90°C induces amaranth protein denaturation and aggregation.•Native amaranth protein films had low WVP but poor mechanical properties.•Heat-treated amaranth proteins films show better mechanical properties but higher WVP.•Heat-treated proteins films are mainly stabilized by disulfide and hydrogen bonds. The usefulness of amaranth protein isolates, native and thermally treated, in edible films preparation was studied. Protein films were prepared by casting using glycerol as plasticizer. Films from amaranth native protein isolates showed low water vapor permeability (WVP) but poor mechanical properties. In order to improve this functionality, proteins were treated at 70 and 90°C which corresponds to the denaturation temperature of the protein fractions present in the isolates. The unfolded conformation of these thermally treated proteins, when partially or totally denatured, favors the interactions between polypeptide chains during the film formation. These interactions lead to a greater cross-linking degree, which was reflected in the lower amount of water-soluble free peptides that were linked to the matrix. In these thermally treated protein films, a greatest contribution of disulfide and hydrogen bonds to the films stabilization was observed. These changes in the films structural properties would confer them a greater tensile strength and lower water solubility but higher thickness and WVP.