Seaweed has been used in many industries, whether directly or its extract. Padina sp. is one of the understudied species of brown seaweed. Brown seaweed have alginate embedded in their cell wall which is a type of hydrocolloids and can be used in many industries and applications including development of biofilms. The main objective of this current study is to develop biofilms using alginate extracted from Padina sp. and incorporated with calcium chloride at different concentrations. Prior to that, the functional groups of Padina sp. and alginate extract were determined. Then, functional groups, surface morphology, mechanical properties, swelling ability and biodegradability of the biofilms were studied using standard methods. The results showed that there were no significant changes in their FTIR spectra with increasing CaCl2 content. Surface morphology showed improvement in bonding while mechanical properties showed the best tensile strength of 9.43mm and 8.61mm elongation-at-break (EAB) after addition of 0.12g CaCl2. As for their swelling and biodegradability, the samples were completely dissolved after one hour and degraded after 24 hours. This shows that the biofilms with CaCl2 indeed improve the quality of alginate-based biofilms which can further be studied to improve other aspects such as water sorption kinetic and thermal stability.

In the present study the stems of the Bridelia stipularis (L.) Blume, which is traditionally used by ethnic communities in Sabah, Malaysia, has been investigated for its chemical composition, total flavonoid content (TFC) and total phenolic content (TPC) via Gas-Chromatography-Mass Spectroscopy (GC-MS) analysis consuming hexane, chloroform and ethyl acetate as extraction solvents and gallic acid and quercetin as internal standards. In vitro antioxidant activity (AA) was determined by the application of 1,1-diphenyl-2-picryl hydrazine (DPPH) radical scavenging assay using tert-butyl-1-hydroxytoluene (BHT) as comparative drug. The GC-MS profiling showed the presence of 1-dodecanol (40.917%), oxalic acid, cyclobutyl octadecyl ester (24.985%), 1-octanol,2-nitro (12.424%), benzaldehyde, 2,4-dimethyl-(9.583%), 4-tridecanol (6.359%) and nitric acid, nonyl ester (5.616%) as major constituents. The TPC (224.62 ± 0.08 mg QE/g) and TFC (160.48 ± 0.08 mg GAE/g) was reported highest for the most polar solvent i.e. ethyl acetate. The in vitro antioxidant study disclosed highest IC 50 value for ethyl acetate (2.15 mg/mL), queued by chloroform (1.19 mg/mL) and hexane (0.89 mg/mL), displaying that polar solvents are good extraction solvents for the identification of free radical scavenging properties, TFC and TPC.

Petroleum-based plastics are mass produced to meet customers’ demand due to their low cost and versatility. However, plastic waste has become a serious environmental problem. Hence, degradable plastics from renewable sources (e.g. biomass) are now trending for their “green” properties. In this paper, properties of biofilms made from whole seaweed (WS), Kappaphycus sp. and pure kappa-carrageenan powder (PC) were compared. Glycerol, as plasticizer, was added at differing amounts (1%, 2%, 3%, 4% and 5%, v/v) and their appearance, physical and mechanical properties, solubility, and biodegradability were studied. As results, for colour difference and transparency, WS-1% showed higher ?E at 17.09 ± 0.85 with highest opacity at 13.73 mm-1 and least ?E was at 2.73 ± 0.13 for PC-5% with opacity at 0.49 mm-1. For mechanical properties, PC-1% has the highest tensile strength and elastic modulus at 26.63 ± 2.18 MPa and 253.53 ± 19.43 MPa, respectively, whereas WS-5% has the lowest at 0.71 ± 0.15 MPa and 2.47 ± 0.44 MPa, respectively. As for biodegradability, by the first week, WS-5% lost 80% of its weight and PC-1% only lost 3%. Overall, PC biofilms showed better quality in terms of mechanical and physical properties but WS biofilms were faster to degrade and dissolve in water. Glycerol concentration affects most of the properties except for mechanical properties for WS and solubility of both. This study suggests that PC may be a better base material for stronger biofilms but WS are a better choice from environmental and cost aspects.

Many reports have described the development and properties of biodegradable plastics made from seaweed hydrocolloids, namely carrageenan, alginate, and agar. Although there is much potential, these seaweed extracts are expensive and require lengthy chemical treatment. In this study, the development of bioplastics using the whole biomass of red seaweed (Kappaphycus alvarezii) as base material, focusing on the optimization of the ratio of biomass (B) to water (W) and plasticizer (glycerol) concentration. The ratios (B: W) were 1:50, 1:60, 1:70, 1:80, and 1:90 (w/v), whereas glycerol was 1, 2, 3, 4 and 5% (v/v). The casting method was used for producing the bioplastics, and their physicochemical properties were tested using standard methods. As the water volume increases, tensile strength, colour intensity and opacity decrease while elongation-at-break and water vapour permeability increase. Similar trends were observed for the effect of increasing glycerol. All the bioplastics were fully degraded via soil burial within two weeks, and their shelf life lasted more than 14 weeks. Interestingly, the bioplastics developed at varied B: W ratios and glycerol concentration exhibit varied features that offer various applications, particularly food packaging.

Plastic pollution has become one of the most concerning problems globally due to excessive use of one-time use plastics. However, bioplastics could be the answer to help combat this problem as they are readily biodegradable. Development of bioplastics was done by mixing seaweed biomass into distilled water at specific ratio, using glycerol as plasticizer. Bioplastics were developed at the ratio of 100:0, 75:25, 50:50, 25:75, and 0:100 K. alvarezii to commercial sodium alginate ratio. Characterization was done based on their appearance, mechanical, thermal and permeability properties, and biodegradability. Resulted data for their appearance showed that when more K. alvarezii was in the mixture there were more colour differences in comparison to white background and the same trend for the opacity due to the natural colour of whole K. alvarezii. As for their mechanical properties, tensile strength of the bioplastics decreased from 100:0 ratio to 0:100 ratio at 7.91 ± 0.45 MPa (100:0), 6.78 ± 0.31 MPa (75:25), 5.20 ± 0.37 MPa (50:50), 4.13 ± 0.17 MPa (25:75) and 3.76 ± 0.14 MPa (0:100), respectively. Same goes for their elastic modulus at 20.93 ± 0.61 MPa (100:0), 16.47 ± 0.99 MPa (75:25), 11.42 ± 0.53 MPa (50:50), 8.78 ± 0.45 MPa (25:75) and 6.65 ± 0.32 MPa (0:100), respectively. This shows that the addition of alginate enhances the elasticity but decreases tensile strength. As a conclusion, developed seaweed-based bioplastics resulted different properties at different mixture ratio show potential to be incorporated into the market as they are a greener option to fight single-use plastic wrappings such as saran wrap, beverages and food additive packets.