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Cassava is a shrub belonging to euphorbiaceous family, widely cultivated in South America, Africa and the Pacific because of its roots with starches of high nutritional value. There is a variety called Manihot utilissima or bitter cassava, which contains high concentrations of cyanogenic elements that make it unusable and poisonous raw material which avoided for human consumption, while the high concentrations of carbohydrates place it as a potential source of starch mainly for industrial use. The wet extraction method was used to get starch from bitter cassava (Manihot utilissima). A factorial (2x3) design was implemented for the experimental set up, with 2 levels of time and mincer speed and 2 for the temperature of H2O, with 2 independent replicates. The comparison with the dry extraction method was also studied, this method consists in drying the bitter cassava over night at 50°C. The yield of starch obtained in wet method ranged from 17.2 to 39.4 g of starch (mean of 26.6 g) obtained from the original samples of 250 g of wet bitter cassava, yielding yields ranging from 6.88 to 15.76% (average 10.64%) of the dry mass. The results were then analysed using PAST software v3.16 for ANOVA statistical evaluation, trend and Pareto were used to determine optimal conditions for the extraction of starch by wet and dry methods. Once the assumptions for analysis of variance (ANOVA) were made, it was concluded that a higher yield of starch is obtained from lower speeds and time, whereas the temperature of H2O is not significant for the process, giving as optimal value for wet method = 0.0678762 for 1/x of the yield of starch obtained, with a starch purity of 64.90% ± 1.21% ranging up to 85.37% ± 1.42%. The extraction of bitter cassava starch has demonstrated its potential for the use of this variety of cassava which generates an added value to the product.

Agriculture modernization and biomass processing generate millions of tons of waste per year containing different amounts and quality of polymeric components such as starch, sugar, lignin, cellulose and hemicellulose. The raw material for extraction was the green plantain peel (Musa paradisiaca), obtained from a local company that produces fried plantain snacks. This work presents the comparisons between the synthesis by wet extraction method and the modification of natural biopolymer with polyhydric alcohol (glycerin). Four blends were prepared at different concentrations of starch, glycerin and water to create a modified biopolymer. Later they were characterized with Fourier Transform Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Amylose-Amylopectin ratio. In the unmodified starch samples, the observed bandwidth at 3373 cm-1 can be attributed to amylopectin O-H stretching (55%) and its width was attributed to the formation of inter- and intramolecular hydrogen bonds, also in the region known as the fingerprint (close IR), ranging from 400 to 1250 cm-1, four characteristic peaks are observed in the spectra between 520 and 1020.16 cm -1, which are attributed to the stretching of the C-O bond. For both unmodified starch and modified starch, the TGA tests showed that the weight loss started at a temperature of about 310 °C, but in modified starch the total degradation temperature increases to about 610 °C. Starch extraction from plantain peel wastes has demonstrated its potential for waste use and the production of value-added products, like degradable polymers. The mixtures of starch, glycerin and water (labeled 1, 2, 3, and 4) have different characteristics, shown in the FTIR spectra. Mixture number 4, with 35% glycerin, has a significant peak at 3425 cm-1, corresponding to the OH group stretching. The bending peak at 1641 cm-1, has less transmittance, since the percentage of water in the mixture is zero. The transmittance band between 1060 and 990 cm-1, is characteristic of the polysaccharides, of amorphous structure.