# An Overview of the Alternative Use of Seaweeds to Produce Safe and Sustainable Bio-Packaging
## 4 Promising Seaweeds to Produce Bioplastics
Alginate, agar, carrageenanan, and cellulose from seaweeds have shown excellent film-forming properties, and are very easy to process [122]. Alginate is the compounds most frequently used for bioplastic production. It is extracted from brown seaweeds, usually from _Laminaria_ sp. and _Ascophyllum nodosum_. It is commercially sold for its gel properties; however, these properties depend on sequence, composition, and the ratio of alginic acid monomers [87]. [PERSON] et al. [59] investigated the alginate extract from the brown alga _Sargassum siliquosum_ as a raw material for the synthesis of bioplastic film. During the treatment process, alginate was mixed with sago starch, sorbitol, and calcium chloride (CaCl\({}_{2}\)). The physical properties of the biofilm were then analyzed. Their results indicate that the biofilm developed using a mixture of 2 g of alginate powder from _Sargassum siliquosum_ and 15% _w/w_ of sorbitol treated with 75% _w/w_ of CaCl\({}_{2}\), appears to possess adequate properties (tensile strength, elongation at break, water vapor permeability, and water solubility). This study suggested that alginate from _Sargassum siliquosum_ as a suitable candidate for the synthesis of bioplastic films [59]. [PERSON] et al. [115] prepared biofilms using crude extracts and cellulose nanocrystals from _Laminaria japonica_ and _Sargassum matans_. It has been noticed that the presence of cellulose nanocrystals enhanced the physicochemical, mechanical, and thermal properties of the biofilm, providing a positive vision towards the use of cellulose to produce bio-packaging. [PERSON] and [PERSON] [116] investigated the biofilms obtained from pure \(\kappa\)-carrageenan and whole seaweed of _Kappaphycus_ sp. The aim of this research was to compare the properties of both biofilms and determine whether the carrageenanan extraction process could be avoided. Their results showed a reduction in brittleness for biofilms derived from the whole algae, but they were weaker due to the low presence of carrageenanan and, consequently, weaker binding intermolecular forces. However, the biofilms produced were both potential candidates to replace petroleum-based plastic and non-degradable packaging [116]. For instance, the best use for this type of bioplastic is single-use packaging for powders, fast foods, candies, or to contain daily-use pharmaceuticals, such as integrators or pills, which do not require great mechanical properties and are easy to open. Another investigation performed by [PERSON] et al. [117] on \(\kappa\)-carrageenanan from _Kappaphycus alvarezii_, evidenced good physical, mechanical, and thermal strength of bioplastic films, suggesting that further research would be beneficial to develop bioplastic film from _Kappaphycus_ sp. in the market. The physical and biological properties of carrageenanans derived from the red seaweed _Eucheuma cottonii_ have been investigated to evaluate these compounds as raw materials for bioplastic production. Semi-refined carrageenanan flour was obtained from _Eucheuma cottonii_, while refined carrageenanans flour was purchased. Bioplastic with extracted carrageenanans showed higher antimicrobial activity, but less strength, than bioplastic produced with refined carrageenanans. Furthermore, the thermal resistance was higher in bioplastic made from refined carrageenanans. However, both bioplastics met the requirements to be used in the market [118]. Agar from _Gracilaria salicornia_ was extracted to identify its physicochemical properties as raw material for bioplastic products. Two extraction methods for agar were tested, and different biofilms were developed to evaluate their properties. The results showed that tensile strength and percent elongation of biofilm obtained using agar from photobleaching extraction (PB) was higher than biofilm from agar obtained by alkali extraction (AE), while thermal stability was higher in the AE agar film. Moreover, the AE agar film was completely decomposed after 30 days in the soil burial test [119].