Zein films with unoxidized or oxidized tannic acid.

• Autores: Talita M Santos, Men de Sá M Souza Filho, Celli R Muniz, João Paulo S Morais, Lloyd Ryan Viana Kotzebue, André Luís Sousa Pereira, Henriette Mc Azeredo
• Localización: Journal of the science of food and agriculture, ISSN 0022-5142, Vol. 97, Nº 13, 2017, págs. 4580-4587
• Idioma: inglés
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• Resumen

  • Corn zein is a predominatly hydrophobic protein, forming films with relatively good water resistance. Tannic acid, especially in its oxidized form, is supposed to cross-link proteins including zein, which may be explored to further enhance the water resistance of zein films. The effects of different contents (0-8 wt%) of unoxidized and oxidized tannic acid (uTA and oTA, respectively) on the properties of zein films at different pH values (4-9) were studied, according to central composite designs.; Results: Increasing tannic acid contents and pH values resulted in decreased water solubility and increased tensile strength and modulus of films. The presence of tannic acid provided the films with a yellowish color and increased opacity. Paired t-tests indicated that oTA films presented higher tensile strength, lower water vapor permeability and lower water solubility than uTA films.; Conclusion: Higher tannic acid contents and pH values resulted in films with better overall physical properties, which might be ascribed to cross-linking, although the films were still not water resistant. The resulting films have potential to be used for food packaging and coating applications. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.