6533b823fe1ef96bd127e814

RESEARCH PRODUCT

Procédé de Liquéfaction, Saccharification et Fermentation Simultanée à Très Haute Gravité utilisant de la farine de manioc pour la production de l'éthanol et valorisation de son sous-produit par la Fermentation en Milieu Solide pour l'alimentation animale

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A simultaneous liquefaction, saccharification and fermentation (SLSF) process at very high gravity of cassava flour for potable ethanol production was developed at lab (1 L) and pilot scale (15 L and 1000 L). Cassava flour (CF) was mixed with tap water to obtain a concentration of 270 g/L dry matter. Sequentially, the mixture of a native starch hydrolyzing enzyme containing a mixture of alpha–amylase and gluco-amylase (Stargen 002 at 2565 GAU/kg CF), gluco-amylase (Amigase Mega L at 0.105% w/w), active dry yeast Saccharomyces cerevisiae (Red Ethanol at 3,5 × 10^7 cells/ml), KH2PO4 (9,9 mM) and urea (16.0 mM) was added into cassava slurry. The SLSF-VHG process including three steps of liquefaction, saccharification and fermentation was simultaneousely carried out in a same bioreactor, at 30°C. Under these conditions, the SLSF process finished after 144h fermentation with the ethanol concentration of 14,4% v/v corresponding to the theoretical ethanol yield of 86,0%. This SLSF-VHG process at very high gravity at pilot scale-1000 L was scaled up in order to evaluate the ethanol yield, energy consumption, production cost and environmental impact (greenhouse gas emissions). The results showed that the ethanol concentration of 13,9% v/v corresponding to a yield of 83,1% of the theoretical ethanol yield was obtained. The GHG emissions of cassava based SLSF process were 186,281 kg CO2eq. By using Response Surface Methodology, the quantity of Stargen 002; Amigase Mega L and yeast inoculation cells was reduced 13,1; 26,6 and 18,0%, respectively. Under these optimized conditions, for SLSF-VHG process at pilot scale 15L, the ethanol concentration obtained was 14,1% v/v corresponding to a yield of 84,0% of the theoretical ethanol yield.Cassava-based distillers dried grains (CDDG) obtained from SLSF-VHG process and from the ethanol plants using conventional process in Vietnam was determined the nutritional compositions. The results showed that, the CDDG produced from the SLSF-VHG and from conventional process had a high content of crude fiber (29,3 and 34,4%, respectively) and a low content of protein (13,2 and 11,9%, respectively). More value can be added to ethanol by-product through solid-state fermentation (SSF) using mold and yeast for animal feed. SSF were conducted with CDDG in 8 and 5 days of fermentation, respectively. Under optimal conditions, the crude protein fraction of CDDG fermented by Trichoderma harzianum BiomaTH1 or Yarrowia lipolytica W29 was increased from 11,84% DM for unfermented sample to 15,29 and 14,06% DM, respectively. In addition, the total amino acids of fermented samples using T. harzianum and Y. lipolytica was increased from 11,01 % DM to 13,86 % DM and 12,39 % DM along with an increase in the essential amino acids content which enhanced by 55% and 22%, respectively, including limiting amino acids in pig feeds. The in vitro protein digestibility was improved significantly from 82,5% to 89,2 and 86,9% for T. harzianum and Y. lipolytica fermentation, respectively.