Development of Bioplastic Films from Sargassum muticum Alginate: Properties and Applications in Food Packaging

To address the challenge posed by the non-degradability of conventional plastic packaging materials and their insufficient treatment, this research undertook the development of a bioplastic film employing alginate sourced from Sargassum muticum, a brown alga, for specific food packaging applications. Several films were prepared using a low cross-linking casting method with varying mass ratios at two distinct temperatures (i.e.: 50 degrees C and 70 degrees C) denoted as FA625 and FA627. The use of crosslinking in this study aimed to enhance the water resistance, mechanical strength, and barrier properties of the bioplastic film, consequently improving its suitability for food packaging applications. Thermal properties were investigated through thermogravimetric analysis/differential scanning calorimetry. Mechanical properties were studied by tensile and hardness measurements. Scanning electron microscopy was performed to conduct the morphological examination. The antimicrobial activity of films was investigated using the agar diffusion method. The differential scanning calorimetry curves of the two films show significant disparities in terms of endothermic and exothermic intensities, suggesting that the cross-linking temperature has a significant influence on the thermal properties. However, it was found that varying the cross-linking temperature did not significantly affect the thermal stability of the alginate-based films. The mechanical properties exhibited noteworthy improvements in the tensile strength, hardness, and thickness of FA627 films compared to those of the FA625 films. The micrographs reveal distinct disparities between the films cross-linked at 50 degrees C and 70 degrees C. Notably, FA625 films depicted a structure with small cavities covering the surface, whereas FA627 exhibited an augmentation of dark voids dispersed in a heterogeneous manner. Moreover, both films demonstrated marginal antimicrobial activity in inhibiting the growth of E. coli and Bacillus cereus, suggesting the potential of sodium alginate-based films to extend the shelf life and improve the safety of packaged food products.