Development and characterization of edible films based on a mixture of the seaweeds Ulva lactuca and Kappaphycus alvarezii

Global consumption of nori, a widely consumed commercial edible algal film, is predominant in Asian countries. As the demand for Asian cuisine rises in Brazil, there is a growing need to explore alternatives to importation, such as producing edible films using seaweeds from the Brazilian coast—specifically Ulva lactuca and Kappaphycus alvarezii . In this study, seaweed film formulations varied in concentrations, from 80% U. lactuca and 20% K. alvarezii to an equal proportion of 50% of each alga, heating at 90°C for 3 and 5 minutes. Results showed that the filmogenic suspensions had a pseudoplastic behavior, with viscosity decreasing as K. alvarezii concentration increased. The resistance of heated gels increased with higher K. alvarezii concentrations and prolonged heating times. Surface uniformity improved with elevated K. alvarezii concentration and extended heating time. As K. alvarezii concentration increased, films exhibited less intense coloration, heightened transparency, and increased solubility. Films with higher K. alvarezii content demonstrated greater tensile strength, albeit without an increase in elongation capacity. Sorption isotherms exhibited a characteristic Type II pattern, and modeling using the GAB model suggested stronger bonds in treatments with extended heating times. Despite the need for enhanced flexibility, the results indicate potential applications in snacks or as alternatives to nori. Notably, these films were produced solely with seaweeds and water, aligning with Nori's minimalistic approach. Treatments with a concentration of 60% U. lactuca and 40% K. alvarezii proved to be the most promising. This study lays the groundwork for future research in developing edible films derived from seaweeds. Graphical abstract