Utilization of taro beneng (xantoshoma undipes k.koch) starch in the manufacture of bioplastics with sorbitol plasticizer and its characterization

Preparation of bioplastics and chitosan with sorbitol plasticizer by varying starch and chitosan in the ratio of 30%: 70%, 40% : 60%, 50% : 50%, 60% : 40%, 70% : 30% and added sorbitol plasticizer with variations of 60% and 80%. Characterization was carried out on the composition of starch and chitosan with the addition of sorbitol plasticizer starting with physical and mechanical testing and obtained 2 bioplastics showing the highest elongation and tensile strength data obtained in sample BSB4 in the ratio of starch and chitosan 60%: 40% by adding 60% sorbitol plasticizer showed an elongation value of 21.68898% and a tensile strength of 1.7352 MPa and sample BSC1 with a ratio of starch and chitosan 30%: 70% with the addition of 80% sorbitol plasticizer resulted in an elongation value of 23.6926% and tensile strength of 2.3997 MPa. The biodegradability test on bioplastics showed a mass reduction for 4 weeks or 28 days with the highest percentage of each variation of starch and chitosan by adding sorbitol plasticizer reaching 19.38%. SEM results show that there is still mixing between starch and a less homogeneous solution as evidenced by several points on bioplastics that are still white, and the same groups are obtained between the constituents of bioplastics, namely O-H, C-H, and N-H.


Introduction
A practical solution for the plastic waste problem in Indonesia has yet to be identified.Environmental reports from 2022 reveal that the total accumulated waste has reached 18.5 tons per year, and plastic waste constitutes 18.6% of this amount [1].As a result, by 2025 there will be 11 billion metric tons of plastic in landfills, which will triple by 2050 [2][3].The process decomposition process has significant challenges; it takes 20 to 500 years to break down [4].Bioplastics is one of the solutions to reduce the problem of plastic waste [5].
The benefit of bioplastic similar with conventional plastics, but bioplastic's distinctive feature lies in their ability to be broken down by microorganisms after use [6].A significant component of bioplastics is a substantial amount of starch, which functions as an oxidation barrier [7][8].The key ingredient in the production of bioplastics is starch, particularly those derived from sources like taro, which are widely utilized in packaging due to their acknowledged to prevent oxidation.According to Kusumasari (2019) et al, reports that taro contains a starch content of 56.29%.In manufacturing bioplastics from taro, additional materials such as chitosan and sorbitol are introduced as plasticizers.Chitosan extracted from insects, shrimp shell, and similar sources is incorporated to improve its mechanical properties, thermal stability, and non-toxic.Combining sorbitol with the polymer solution facilitates the formation of hydrogen bonds between molecules, thereby reducing hydrogen bonds within the bioplastic [9][10][11][12][13][14]. Bioplastics derived from taro starch are expected to provide an innovative, readily biodegradable, and environmentally friendly plastic solution.

Materials
From Namotrasi Pasar IV Village, Sei Bingai District, Langkat Regency, North Sumatra Province, the beneng taro plant was obtained.Chitosan using commercial chitosan obtained from CV. chiMultiguna store, Aquadest, sorbitol, and acetic acid from Rudang Jaya Chemical Store.

Preparation of Taro Beneng Tubers into Starch
The taro beneng tubers obtained are then cleaned thoroughly, peeled, and cut into chips shapes.After that, taro beneng tubers are mashed using blender.The mashed taro beneng tubers are filtered and left to settle for 24 hours, every 5 hours it is washed until a white sediment is obtained.The sediment is left undisturbed at room temperature for 60°C for 24 hours.After obtaining dried starch, it is ground using mortar and sifted through a 200-mesh sieve.It is then analyzed to determine starch, protein, fat and water content.

Solution Preparations 2.3.1
Preparation of ‫ܪܥ(‬ ଷ ‫)ܪܱܱܥ‬ Solution A 1000 mL glass beaker is prepared for dilute acetic acid by adding 20 mL of it and then adding distilled water (aquadest) adding 980 mL to reach a total volume of 1000 mL, the mixture is stirred at 25°C until it reaches homogeneity [15].

Preparation of Chitosan Solution
Prepared a 250 mL glass beaker, then poured with chitosan.Disolve in a 2% CH3COOH solution with a mass-to volume ratio of 1:40 (w/v) [15].

Preparation of Starch Solution
Prepared a 500 mL glass beaker, put the starch into it and dissolve in distilled water (aquadest) with a mass ratio of starch to distilled water volume of 1:20 (w/v) [15].

Manufacture of Bioplastics
A specific mass of starch and chitosan were weighed at various ratios of 30%:70%, 40%:60%, 50%:50%, 60%:40%, and 70%:30% of the total starch and chitosan of 5 grams.A starch solution was made with a ratio of 1:20 (w/v).While, a chitosan solution was made by dissolving chitosan and 2% acetic acid, with a chitosan-to-acetic acid ratio of 1:40 (w/v).Subsequently, a sorbitol solution is made using variations of 60% (v/w) and 80% (v/w) at a gelatinization temperature of 80°C, stirred with a magnetic stirrer at 400 rpm for 30 minutes.The chitosan solution is slowly added to the mixture, and after 30 minutes, sorbitol is added with variations of 60% (v/w) and 80% (v/w) to the starch-chitosan solution, stirred for 15 minutes.The magnetic stirrer was then turned off, and the solution in the beaker glass was cooled before molding.The solution was poured into molds and then dried in an oven at T = 70°C for 24 hours.It is then released from the mold and placed in a desiccator for 24 hours before characterization of the bioplastic.The research showed that 20.5% of the taro beneng tubers, or around 20.5 grams per 100 grams, were retrieved.Compared to experiments conducted by Maghfirah et al.2023, the amount of porang (Amorphophallus Oncophillus) starch in a mass of 100 g is roughly 14.517% higher [16].The results of the tests for the water and fat contents of taro beneng starch were 8.58% and 12.71%, respectively, while the result of the protein test using the Kjeldahl method and 1 gram of starch was 3.51%.

Characterization of Bioplastic
It is utilizing ASTM D-1005 for thickness measuring.Thickness is the most critical measurement parameter for bioplastics since it affects the material's density, tensile strength, and elongation [17].As shown in Table 3, sorbitol concentration increases along with thickness.For instance, at 60% sorbitol, thickness rises to 0.11 mm when sorbitol concentration is increased to 0.16 mm.The need for bioplastic will expand as compostable materials are used in production at a greater rate [18]  The density is 1.28 gr/cm3 when 60% sorbitol plasticizer is added; when 80% plasticizer is used, the density is 1.84 gr/cm3.According to Singan and Lielw's (2017) research, the rise in density value is impacted by the growing quantity of plasticizers applied to bioplastics.Water absorption increases by 33.3% with the addition of 60% sorbitol plasticizer and by 40% with the addition of 80% sorbitol plasticizer.An increase in the chain's space and a deterioration of the bonds keep the polymer molecules together.Increases the solubility of the film by facilitating water diffusion into the polymer matrix [19].The results of the bioplastic degradation test showed a significant decrease in mass every week.The biodegradation process of bioplastics begins with the attack of the bioplastic surface by microorganisms; then, the microorganisms attack the bioplastic polymer as a carbon source.When bioplastic biodegradation occurs, microorganisms release enzymes that break down the polymer chains.The highest degradation percentage value was in the addition of 80% sorbitol plasticizer with a composition of 70% starch and 30% chitosan because starch and sorbitol, which are hydrophilic, are more easily soluble in water, so the higher the levels of starch and sorbitol plasticizer, the percentage of bioplastic degradation produced will also increase [6].concentration.FTIR analysis aims to determine the functional groups contained in biodegradable plastic [23].The wave number in the FT-IR absorption analysis results of sorbitol shows a value of 3290.42 cm -1 , which is the O-H functional group, and 2930.69 cm -1 , which shows the C-H functional group.The wave number in the results of FT-IR analysis of taro beneng starch shows a value of 3300.7 cm -1 , which is the Ol-H functional group, and 2928.7 cm -1 , which shows the C-H functional group.In the Chitosan FT-IR wave number analysis, the value 3308.23 cm -1 is the O-H functional group, 2917.83cm-1 is the C-H functional group, and 1589.18cm -1 is the N-H functional group.The FT-IR results of the resulting bioplastics obtained the same functional groups as the components that make up bioplastics, namely, C-H, O-H, and N-H.

Conclusion
The addition of the plasticizer sorbitol in the production of bioplastic from taro starch results in a more elastic plastic, as evidenced by the high elongation values.However, as the concentration of sorbitol increases, the tensile strength values decrease.Additionally, higher percentages of added chitosan and sorbitol concentration prolong the degradation process, indicating the possibility that chitosan and sorbitol resist water absorption.SEM microstructure still shows agglomeration due to solution mixing.FT-IR found no new functional groups in each constituent of bioplastics, namely C-H, O-H, and N-H, no N-H functional groups were found in starch and sorbitol.