Biodegradability testing methods being used nowadays have many disadvantages; they are time-consuming, inefficient medium used, and too much sample needed to do the test. This work aimed to study the biodegradability of starch-based bioplastics by modified ASTM G21-70 method using Salt Agar (SA) medium, dip-hanging method using sterile water, and Soil Burial Test (SBT) method. Bioplastics were prepared by mixing cassava starch and glycerol with a ratio of 3:1 (%, w/w) through a series of processes: (1) blending of starch and glycerol for 3 min, (2) extruding of the starch-glycerol mixture by using a single screw extruder at 80-130°C, and (3) compression molding at temperature and pressure of 150°C and 50 kgf/cm2, respectively. Aspergillus niger was used as bioplastic-degrading fungi for the modified ASTM G21-70 and dip-hanging methods, while compost-soil was used as a source of bioplastic-degrading microbes in SBT method. Bioplastics of 2x2 cm in size were applied to the tests for 10 days. The growth of fungi on the surface of bioplastics was observed visually at two days intervals. A. niger grew well on the surface of bioplastic sample in modified ASTM G21-70 method, indicated that the bioplastic could be degraded by the fungi. On the other hand, the growth of A. niger was poor in the dip-hanging method, even though weight loss of 11.5% occurred. Physical properties changing were indicated in the SBT method. On the 10th day, cracks were observed on the surface of the bioplastic sample, the color of the sample became darker even the bioplastic became fragile, and the weight loss reached 29.89%.
Indonesia is a maritime country that is rich in seaweed. However, seaweed fermentation into lactic acid is not yet usually. Seaweed fermentation has outstanding potential because it has the most abundant polysaccharides compared to other sources. This research aims to synthesize lactic acid by fermentation using a single culture of Lactobacillus plantarum (L. plantarum) and two substrates, namely seaweed flour and refined salt Kappa-Carrageenan (RKC). Lactic acid was analyzed by fourier-transform infrared (FT-IR) spectroscopy and its concentration was determined by gas chromatography-mass spectrometry (GC-MS). The proximate analysis showed that crude Fiber and starch levels in seaweed are 25.37% and 14.66% (w/w) and also in RKC are 16.45% and 1.07% (w/w), respectively. The highest reducing sugar was attained at H2SO4 2% (w/w), which were 51,184 mg/L in RKC and 24,824 mg/L in seaweed flour. Based on FT-IR data, lactic acid characteristic signals were found at broadband approximately 3000 - 3500 cm−1, which indicated the presence of OH band, a band at 1656 cm−1 revealed C=O stretching of carbonyl groups, and a band at 1118 cm−1 for C-O stretching of alcohol. Based on GC-MS data, the highest lactic acid production was 42,267 mg/L in RKC and 37,130 mg/L in seaweed flour. In this study, we can conclude that the efficiency of hydrolysis and fermentation of RKC was better than seaweed flour. However, the substrate concentration for optimum lactic acid production was unknown, so a more in-depth study was needed.
Thermoplastic agar (TPA) was prepared by a melt extrusion process and the effects of water contents on the material properties of these foams were investigated. Bioplastics were produced by mixing agar, glycerol, and water at ratio agar; glycerol: water was 5:3:2; 5:3:3; and 5:3:4 through the melting process at 120 °C and 18 rpm. The addition of water affected the extrusion process more easily, so the pellet could move easily from the extruder, but the moisture content of TPA increased with water addition. Then, TGA analysis showed no difference in decreasing mass in the sample with water addition. Permeability, elongation, contact angle, density, moisture content, and WVTR of bioplastics increased with water addition. The FTIR curves indicated that the interaction between water and agar may form much more hydrogen bonds. The best treatment was bioplastics with agar:glycerol:water=5:3:2, which have characteristics: tensile strength 16.19 MPa, elongation at break 102.56%, moisture content %, contact angle 72.81°, density 1.38 g/ml, moisture content 3.09%, transparency value 0.067, and WVTR 1334.59 g/m2.24 h.
SYNTHESIS L-LACTIC ACID FROM FERMENTATION OF CASSAVA PULP BY USING TEMPEH INOCULUM. This study used cassava waste pulp as a fermentation substrate to produce lactic acid using a tempeh inoculum. Tempeh inoculum is a mixed culture of Rhizopus with Rhizopus oligosporus as the primary fungus. Lactic acid is an organic acid most widely used in the food, pharmaceutical, cosmetic and chemical industries. One of the important uses of lactic acid is as a raw material for producing Polylactic Acid (PLA) biopolymers, namely polymers that can decompose naturally in a relatively fast time. The analysis was performed using the Response Surface Methodology (RSM) method and the Box Behnken Design (BBD) experimental design with substrate concentration parameters, inoculum concentration, and incubation time on lactic acid. The fermentation process is carried out using a flask shaker at a temperature of 30 ºC, pH 6.0, and a rotational speed of 150 rpm. The optimum yield for lactic acid is 6.65 g/L. It was acquired at substrate 20 g/L, inoculum concentration 0.30 % (w/v) at an incubation time of 72 hours.
Microcrystalline cellulose (MCC) is pure cellulose isolated from alpha cellulose. The demand for renewable and sustainable raw materials for the industry has developed as one of the most pressing challenges in recent decades. The seaweed processing industry produces a large amount of solid fibrous waste, which can be utilized as an additional source of cellulose feedstock. The increase in seaweed production continues to increase, as well as waste that can be used as another source of cellulose raw materials. This study used red seaweed i.e., Gracilaria verucosa and Echeuma cottonii to produce high-quality MCC. Gracilaria verucosa and Echeuma cottonii are treated chemically through alkali, bleaching, and acid hydrolysis to obtain pure MCC. Following the X-ray diffraction (XRD) analysis result, MCC in the standard had a crystallinity of 67.2%, while the Gracilaria verucosa-MCC (GV-MCC) sample was 53.0% and Echeuma cottonii-MCC (EC-MCC) was 58.4%. Fourier transform infrared (FTIR) spectroscopy showed that GV-MCC and EC-MCC almost resemble the MCC standard. The morphology characteristic from Scanning electron microscope (SEM) analysis presented the difference between raw material before and after isolation into MCC. According to the Particle size analyzer (PSA) result, the mean sizes of EC-MCC and GV-MCC are 0.786 and 0.522 µm, respectively. The isolation of MCC from red seaweed has the potential to be used in a wide range of industries.
Effect of Agar and kappa-Carrageenan on Thermal and Mechanical Properties of Thermo Plastic Starch (TPS) Thermoplastic starch needs to be blend with other materials because of its limited properties. In order to gain the desired properties, the interaction between the added component (filler, plasticizer, second polymer, etc) must be concerned as it can affect the performances of the final product. Thermoplastic starch has been successfully made with mixing and compression molding with the addition of agar and kappa-carrageenan. The effect of the added material has been studied with FTIR, Tensile, DSC, and TGA to investigate their mechanical and thermal properties. The FTIR spectrum has shown the shifting around the methyl group (C-H), a carboxyl group (C-O), and a hydroxyl group (O-H). Thermal analysis results presented different patterns in melting and degradation behavior. The tensile strength value did not show significant improvement with the presence of agar and kappa-carrageenan. It is shown that the addition of agar and kappa-carrageenan affects thermal behavior but does not significantly impact the mechanical properties.
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