Industrial Crops and Products 56 (2014) 160–165 Contents lists available at ScienceDirect Industrial Crops and Products jo u r n al homep age: www.elsevier.com/locate/indcrop Pilot scale simultaneous saccharification and fermentation at very high gravity of cassava flour for ethanol production Chinh-Nghia Nguyen, Thanh-Mai Le, Son Chu-Ky ∗ Department of Food Technology, School of Biotechnology and Food Technology, Hanoi University of Science and Technology, 1 Dai Co Viet, Hai Ba Trung, Hanoi 10000, Viet Nam a r t i c l e i n f o Article history: Received 30 August 2013 Received in revised form 5 February 2014 Accepted 8 February 2014 Available online 28 March 2014 Keywords: Simultaneous saccharification and fermentation (SSF) Very high gravity (VHG) Ethanol Cassava flour a b s t r a c t We developed a simultaneous saccharification and fermentation (SSF) process of cassava flour at very high gravity (VHG). Cassava flour (CF) was dissolved in water to reach 315.4 g/l dry matter, and then the mixture was liquefied at 80 ◦ C for 90 min by using alpha-amylase (3532 AAU/kg CF) and beta-glucanase (2812 U/kg CF). SSF of liquefied mash of cassava was performed at 30 ◦ C with the simultaneous addition of two glucoamylases (Distillase ASP at 540 GAU/kg CF and Amigase Mega L at 0.035% w/w), active dry yeast (1.5 × 10 7 cells/l), urea (12 mM) and KH 2 PO 4 (4 mM). Under these conditions, the SSF process finished after 72 h. The ethanol content achieved 17.2% v/v corresponding to 86.1% of the theoretical ethanol yield at lab scale and decreased to 16.5% v/v corresponding to 83.6% of the theoretical ethanol yield at pilot scale. Therefore, the SSF of cassava flour under VHG condition could have a great potential for the ethanol industry in Vietnam and South East Asia. © 2014 Elsevier B.V. All rights reserved. 1. Introduction According to the increasing price of oil, bio-ethanol is known as an ideal candidate to replace the role of fossil fuel. Thus, the research on this renewable source becomes growingly important for humans, especially in terms of improving the productivity, the efficiency and decreasing production cost. In Vietnam and in South East Asia, cassava is considered an attractive raw material for bio- ethanol production thanks to the following advantages: (i) the ease of plantation in various soil types and climate conditions; (ii) a very low input and investment for planting; (iii) “all year round” availability of feedstock in the form of fresh roots and dry chips; (iv) a high starch-containing raw materials and a lower proportion of fibers (Sriroth et al., 2007). Indeed, the Vietnamese Ministry of Industry and Trade declared that bio-fuel production will achieve 1.8 million tons in 2025, which accounts for 5% of country’s demand (Ministry of Industry and Trade, 2007b). Moreover, the government also adapted the policy to improve the beverage ethanol industry in Vietnam. By the development strategy of beverage ethanol pro- duction in Vietnam (Ministry of Industry and Trade, 2007a), ethanol industry will produce 188 million liters ethanol for food industry in 2025. Overall, the beverage and bio-ethanol industry has a great potential in Vietnam in the future. ∗ Corresponding author. Tel.: +84 4 3868 0119; fax: +84 4 3868 2470. E-mail addresses: son.chuky@hust.edu.vn, kysonchu@gmail.com (S. Chu-Ky). Besides the conventional process of ethanol production, simul- taneous saccharification and fermentation (SSF) process has been widely used in the world, but only recently introduced to Vietnam in order to augment ethanol yield and shorten time production. Indeed, after liquefaction by alpha-amylase, glucoamylase is added to the slurry, concomitantly with yeasts, and the SSF is conducted in a single reactor. The presence of yeast along with enzymes mini- mizes the sugar accumulation in the bioreactor. Moreover, since the sugar produced during starch or cellulosic breakdown slows down alpha-amylase action, higher yields and concentrations of ethanol are possible using SSF (Das Neves, 2006; Klasson et al., 2013; Molaverdi et al., 2013; Scordia et al., 2013; Wang et al., 2013; Yingling et al., 2011a,b). The SSF process has been successfully car- ried out on different substrates such as flax shive (Klasson et al., 2013), sweet sorghum stalk (Molaverdi et al., 2013), giant reed (Scordia et al., 2013), sweet sorghum bagasse (Wang et al., 2013), potato tubers (Srichuwong et al., 2009) and cassava (Chu-Ky et al., 2009; Yingling et al., 2011b). Therefore, it is of interest to improve the efficiency of the SSF process in the ethanol industry in Vietnam. Very high gravity (VHG) technology has been introduced to increase the volumetric productivity and the cost effectiveness of the SSF process. In VHG technology, mash preparation con- tains at minimum of 270 g/l dry matter (Bayrock and Ingledew, 2001). This technology has a great deal of advantages in ethanol production: (i) increasing plant capacity and reduction in capital costs; (ii) increasing plant efficiency; (iii) reducing risk of con- taminating bacteria (Thomas et al., 1996; Yingling et al., 2011a,b). http://dx.doi.org/10.1016/j.indcrop.2014.02.004 0926-6690/© 2014 Elsevier B.V. All rights reserved.