Envelhecimento de filmes comestíveis ativos: nanoencapsulação do carvacrol na matriz gelatina/amido de mandioca

Abstract

Packaging made from biopolymers containing protein and starch has been the subject of research, and has proven to be sustainable alternatives for partial or total replacement of petroleum derivatives. Therefore, this work consists in presenting an environmentally correct alternative for food packaging with the use of natural biopolymers such as gelatine and cassava starch. In addition, this package has an active agent (carvacrol), added in different concentrations, which has the function of inhibiting the growth of microorganisms on the food surface, thus increasing its shelf life. The casting method was used in the formulation of the composite films and after the incorporation of the chosen antimicrobial was made. In order to evaluate the structure of the packaging during the 150 days period, after the composite film, the films were characterized by mechanical properties (Elongation and tensile at break), thermal (TG and DSC), thickness, solubility, moisture, water vapor permeability, opacity, scanning electron microscopy and spectroscopy infrared. The composite films obtained presented low solubility in water, water permeation and humidity. In addition, the films had translucent characteristics that vary with the amount of oil added, that is, the larger the amount of oil the opaquer the composite film becomes. However, these features were not dramatically affected over time. However, the mechanical properties of elongation and tension at the rupture underwent changes with time and with the amount of oil. The first one had a considerable increase in both aspects, whereas in the second one the opposite occurred. In the TGA analysis of the composite film, it was possible to observe the percentage of moisture loss for both films analyzed, besides the degradation temperatures of the biopolymer matrix and the antimicrobial compound, it was also verified that these temperatures did not suffer variation as the time of storage. In the thermal analysis of DSC, the glass transition (Tg) and the melt (Tf) transition temperatures in which the composite films have a change of state were verified by the application of heat flux, the degradation of the antimicrobial compound carvacrol in temperature similar to that found in the TGA (200ºC), thus confirming that the films obtained in the present study are temperature resistant. In infrared spectroscopy it was possible to identify the presence of carvacrol in different quantities in the analyzed films, at a certain peak of wavelength, in addition in the time of 150 days of storage this peak continued appearing, thus indicating that the composite film to be used as Antimicrobial packaging still presents its main compound responsible for the increased shelf life of the product being packaged. In this same analysis it was also possible to recognize the presence of the biopolymers (gelatine and cassava starch) used in the matrix in the film and to prove the formation of a polymer blend. It is then concluded that the composite films can be applied as food packaging and that maintain their structure and antimicrobial property during the time period of 150 days.