Natural deep eutectic solvent of choline chloride with oxalic or ascorbic acids as efficient starch-based film plasticizers

• Published in: Polymer (Guilford) Vol. 259; p. 125314
• Main Authors: Sousa, Alex Sandro Bezerra de, Lima, Renato Pereira, Silva, Mariany Cruz Alves da, Moreira, Dayse das Neves, Pintado, Maria Manuela Estevez, Silva, Silvanda de Melo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 27-10-2022
• Subjects: Ascorbic acid; Cassava starch; Mechanical properties; NADES; Oxalic acid; Cassava starch; Mechanical properties; Ascorbic acid; Oxalic acid; NADES
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2022.125314

Natural deep eutectic solvents (NADES) of choline chloride/oxalic acid (OA) and choline chloride/ascorbic acid (AA) were evaluated as innovative candidates for cassava starch-based film plasticizers, aiming to replace the glycerol standard. NADES-OA and NADES-AA were compared at five levels with a 40% glycerol standard. NADES were characterized by Fourier Transform Infrared (FTIR), and the films were subjected to optical, physical, and mechanical evaluations and structural analysis by X-ray Diffractometry (XRD) and FTIR. NADES-OA and NADES-AA improved the films' optical, physical, and mechanical properties, providing characteristics similar or superior to those plasticized with glycerol. NADES-OA showed a greater plasticizing effect, requiring a lower plasticizer concentration (30%) for the films to reach similar mechanical and physical characteristics to those with 40% glycerol. In addition, it presented a lower opacity and crystallinity index. Films with 60% NADES-AA had the highest elasticity and the lowest opacity but were highly water soluble and slightly yellow. Novel data reported here indicate that NADES-OA and NADES-AA can be used as efficient plasticizers for starch-based films, presenting vast potential for use as films or coatings for the agricultural and food industries.
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•Oxalic acid (OA), ascorbic acid (AA) NADES, and glycerol were tested as plasticizers.•NADES and glycerol cassava starch film structures were evaluated by FTIR and XRD.•Mechanical properties of film with NADES-AO are superior to those with glycerol.•Films with NADES-AA have superior barrier properties and lower moisture content.•NADES are more efficient plasticizers than glycerol in cassava starch films.