Dados do Trabalho

Título

Production, characterization, and application of films composed of guar gum with addition of nanoclay

Introdução

The recent focus of research on polymeric materials has been to find sustainable and effective solutions for food applications. Vegetable polysaccharides emerge as promising alternatives, being derived from renewable and non-fossil sources. Guar gum (GG) is a galactomannan recognized by the FDA as “Generally Recognized as Safe” (GRAS) products, it stands out for its availability, low cost, non-toxic nature, biodegradable, however, it has high permeability to water vapor and mechanical properties poor.

Material e Métodos

The films were prepared using the casting technique with 1% GG (w/v), 20% glycerol (w/w) and 0-15% (w/w) of Lap. The solutions were stirred in a mechanical shaker at 80ºC for 1 hour, film-forming solutions were centrifuged (2000 rpm/10 minutes), placed in acrylic plates and dried at room temperature. The obtained films were conditioned in a desiccator with 58% RH for traction tests (tensile strength TS, elongation at break EB, and elastic modulus EM), water vapor permeability (WVP), thickness, moisture content, solubility, contact angle, color, opacity, and transparency, and conditioned in a desiccator with ≈ 5%RH for DR-X and FTIR tests. The films were tested in grape juice exposed to light as an alternative of UV-barrier materials.

Resultados e Discussão

The addition of Lap did not affect the thickness of the films and increased the moisture content (2.6±0.2%-14.9±0.9%), however, the solubility in water decreased (83.4±3.6%-26.5±1.9%), as well as the contact angle (112.2±1.6º to 91.3±0.6º). The addition of Lap increased film opacity. For the mechanical properties, there was no significant difference (ANOVA, Tukey test at 5%) in TS (28.8-37.8 MPa), EB (27.8-43.2 %) and EM (1.0-2.6 MPa). In the DR-X test, the diffractograms showed characteristic peaks of galactomannans (18.0°) and in approximately 3° there was an increase in the signal that may be related to the exfoliation of the laponite plates. The FTIR curve showed characteristic peaks of galactomannans (811 and 869 cm-1) that are related to anomeric configurations from α-d-galactopyranose units and β-d-mannopyranose units, respectively. Films with 15% laponite reduce anthocyanin degradation by up to around 20%.

Conclusão

Loading guar gum films with Lap could be an alternative to develop biopolymer films with UV-barrier properties with potential food applications.