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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.