Cassava Pulp as a Biofuel Feedstock of an Enzymatic Hydrolysis Proces

Abstract

Cassava pulp, a low cost solid byproduct of cassava starch industry, has been proposed as a high potential ethanolic fermentation substrate due to its high residual starch level, low ash content and small particle size of the lignocellulosic fibers. As the economic feasibility depends on complete degradation of the polysaccharides to fermentable glucose, the comparative hydrolytic potential of cassava pulp by six commercial enzymes were studied. Raw cassava pulp (12% w/v, particle size <320 µm) hydrolyzed by both commercial pectinolytic (1) and amylolytic (2) enzymes cocktail, yielded 70.06% DE. Hydrothermal treatment of cassava pulp enhanced its susceptibility to enzymatic cleavageas compared to non-hydrothermal treatment raw cassava pulp. Hydrothermal pretreatment has shown that a glucoamylase (3) was the most effective enzyme for hydrolysis process of cassava pulp at temperature 65 °C or 95 °C for 10 min and yielded approximately 86.22% and 90.18% DE, respectively. Enzymatic pretreatment increased cassava pulp vulnerability to cellulase attacks. The optimum conditions for enzymatic pretreatment of 30% (w/v) cassava pulp by a potent cellulolytic/ hemicellulolytic enzyme (4) was achieves at 50 °C for 3, meanwhile for liquefaction and saccharification by a thermo-stable α-amylase (5) was achieved at 95 °C for 1 and a glucoamylase (3) at 50 °C for 24 hours, respectively, yielded a reducing sugar level up to 94,1% DE. The high yield of glucose indicates the potential use of enzymatic-hydrothermally treated cassava pulp as a cheap substrate for ethanol production.

Chemical composition and in vitro gas production of fermented cassava pulp with different types of supplements

“…In terms of enzyme supplementation, the high yield of glucose indicates the potential use of enzymatic-hydrothermally treated cassava pulp has been reported by Djuma'ali et al (2011). Sriroth et al (2000) also have reported that enzymatic treatment of cassava pulp increases the susceptibility of starch molecules to alpha-amylase hydrolysis thereby increases the amount of reducing sugar for further fermentation by microorganisms.…”

Functional Characterization of Recombinant Raw Starch Degrading α-Amylase from Roseateles terrae HL11 and Its Application on Cassava Pulp Saccharification

“…Typically, raw substrate hydrolysis requires the synergistic interaction of enzyme composites to achieve complete saccharification (conversion yield ≥80%), such as cooperation of α-amylase and glucoamylase in starch hydrolysis [73]. In addition, saccharification of raw cassava pulp needs the synergistic interaction of various starch-degrading and fiber-degrading enzymes to expose the complex structure of pulp to facilitate enzyme accessibility [5,74,75]. In summary, HL11Amy exhibited effective raw cassava pulp hydrolysis, which could be appropriate to promote further amylolytic enzymes in the non-thermal starch saccharification process by releasing solubilized starch.…”

Clostridium manihotivorumsp. nov., a novel mesophilic anaerobic bacterium that produces cassava pulp-degrading enzymes

“…The utilization rather than discarding of cassava pulp will, therefore, reduce the negative impact on environmental and human health. On a dry weight basis, cassava pulp is mainly composed of starch (50-60%, w/w) with 15-27% (w/w) cellulose and hemicelluloses contents, pectin (7.0-7.3%, w/w), and lignin (3.4-4.6%, w/w) (Djuma'ali et al, 2012;Vaithanomsat et al, 2013). In general, the saccharification of cassava pulp to fermentable sugars used in the production of high value-added products requires the action of enzymes belonging to glycoside hydrolases (GHs), which hydrolyze the glycosidic bonds of starch, cellulose and hemicellulose contained in lignocellulose (Naumoff, 2011;Linares-Pastén, Andersson & Karlsson, 2014).…”