Bi-layer Gelatin Film: Activating Film by Incorporation of “Pitanga” Leaf Hydroethanolic Extract and/or Nisin in the Second Layer

• Published in: Food and bioprocess technology 2021, Vol.14 (1), p.106-119
• Main Authors: Luciano, Carla Giovana, Rodrigues, Mariane Mendes, Lourenço, Rodrigo Vinícius, Bittante, Ana Mônica Q. B., Fernandes, Andrezza Maria, do Amaral Sobral, Paulo José
• Format: Article
• Language: English
• Subjects: Additives; Agriculture; Antiinfectives and antibacterials; Antioxidants; Bilayers; Biotechnology; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Contact angle; Food additives; Food Science; Fourier transforms; Gelatin; Humidity; Infrared spectroscopy; Leaves; Listeria; Mechanical properties; Molecular interactions; Nisin; Original Research; Permeability; Polymers; Thickness; Water vapor; X-ray diffraction
• ISSN: 1935-5130; 1935-5149
• DOI: 10.1007/s11947-020-02568-w

Active films have gained increasing interest because of their potential to reduce the amount of additives into foods. The aim of this work was to produce and characterize bi-layer films based on gelatin in both layers, in which the nisin and/or “pitanga” leaf hydroethanolic extract was loaded in the second layer. The bi-layer gelatin-based films were characterized regarding humidity and solubility in water, color, microstructure, mechanical properties, water contact angle, water vapor permeability, UV/Vis barrier, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and antimicrobial and antioxidant activities. The addition of active compounds on the second layer of the films was sufficient to produce active films. The presence of additives in the films’ second layer did not affect film humidity, water vapor permeability, or the molecular interactions of the polymer matrix as assessed by FTIR. Although some mechanical properties and the water contact angle were affected, it was not necessarily deleterious to the films’ functionality. All active films presented activity against Staphylococcus aureus and Listeria monocytogenes even with the additive being present only in a thin layer. And, as it could be expected, only films containing PLHE presented antioxidant activity. This study concluded that the bi-layer technique permits the production of active films while employing only one third of the amount of additives when compared to similar monolayer films of the same thickness, as produced in a previous work.