Biofilmes comestíveis de amido de cará-roxo, alginato de sódio e timol para revestimento de maçãs e morangos

Abstract

Edible biofilms are safe and ecological alternatives to conventional petroleum-based plastic packaging, which can efficiently increase food shelf life. Therefore, the objective of this work was to produce biofilms of natural polymers such as starch extracted from yams, sodium alginate and thymol, characterize them and apply them as a coating for apples and strawberries to prolong their conservation and maintain their desirable organoleptic characteristics. The purple yam starch was successfully extracted and, like the sodium alginate, it was subjected to the gelation process, generating stock solutions with and without thymol that were deposited in Petri dishes and, when dried, formed biofilms, a process known as casting. These samples were characterized by moisture content, solubility in water and ethanol, scanning electron microscopy (SEM), thickness, water vapor permeability (WVP), opacity, colorimetry, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The fruits, on the other hand, underwent a coating with these solutions and were monitored through weight loss and change in visual appearance. The moisture content and solubility in water were within the expected range for the biofilms produced with the intended purpose. The solubility results in alcohol indicate a new line of research based on more complete digestibility studies. It was possible to measure the micrometric thickness of the biofilms through SEM images, which also allowed the observation of their morphology and how the application of ultradispersion may have contributed to a porous texture and an irregular surface of the biofilms. The results also indicate that thymol may have contributed to the increase in PVA. The analyzes of the optical properties showed that the biofilms were transparent without any type of color trend and the addition of thymol did not interfere with the opacity. The FTIR indicated the main vibrational groups of the materials used, and showed that thymol did not change the composition of the biofilms. Through the thermal analysis it was possible to observe that the biofilms had greater thermal stability than the isolated materials. Considering that there were no major differences in the performance of the samples, the AC-Br sample was chosen as the most profitable and easy to produce as an ecological material that contributes to the preservation of food and does not pose risks to human health.