Simultaneous saccharification and fermentation of sweet potato powder for the production of ethanol under conditions of very high gravity

Abstract

Due to its merits of drought tolerance and high yield, sweet potatoes are widely considered as a potential alterative feedstock for bioethanol production. Very high gravity (VHG) technology is an effective strategy for improving the efficiency of ethanol fermentation from starch materials. However, this technology has rarely been applied to sweet potatoes because of the high viscosity of their liquid mash. To overcome this problem, cellulase was added to reduce the high viscosity, and the optimal dosage and treatment time were 8 U/g (sweet potato powder) and 1 h, respectively. After pretreatment by cellulase, the viscosity of the VHG sweet potato mash (containing 284.2 g/L of carbohydrates) was reduced by 81%. After liquefaction and simultaneous saccharification and fermentation (SSF), the final ethanol concentration reached 15.5% (v/v), and the total sugar conversion and ethanol yields were 96.5% and 87.8%, respectively.

Viscosity reduction of cassava for very high gravity ethanol fermentation using cell wall degrading enzymes from Aspergillus aculeatus

“…Various cell wall degrading enzyme activities including pectinase (polygalacturonases), xylanase, cellobiohydrolases and mannanase have been shown to reduce viscosity of root mashes [11]. Viscosity of sweet potato mash was decreased by treatment with xylanase [13] and cellulase from T. reesei [27]. The developed VHG process using xylanase-pretreated sweet potato root mash has been implemented in pilot and industrial scale [28].…”

Batata-doce [<i>Ipomoea batatas</i> (L.) Lam.] nas roças e quintais do litoral paulista: diversidade genética morfoagronômica, com base em morfometria geométrica, descritores e produção de bioetanol

“…No tocante aos biocombustíveis, tem sido considerada um substrato promissor, uma vez que tem um maior rendimento de amido por unidade de área cultivada quando comparada com os grãos (KIM; HAMDY, 1985;ZISKA et al, 2009;CAO et al, 2011;LEE et al, 2012; DUVERNAY; CHINN; YENCHO, 2013).…”

“…Estudos vêm sendo desenvolvidos para averiguar o potencial do bioetanol derivado da batata-doce no Brasil (SILVEIRA, 2008;GONÇALVES NETO et al, 2011;MARTINS et al, 2012;TABORDA et al, 2015), na China (CAO et al, 2011;WANG et al, 2013), nos Estados…”

“…Em virtude deste cenário, uma alternativa viável tem sido a utilização do bioetanol, um recurso mais limpo e sustentável que os combustíveis fósseis, que minimiza os impactos da emissão de gases que provocam o efeito estufa (CAO et al, 2011). O bioetanol pode ser produzido pela fermentação direta de açúcares ou pela hidrólise do amido e da celulose, em açúcares fermentescíveis (BALAT; BALAT, 2009).…”

“…Vários estudos vêm sendo desenvolvidos para explorar o potencial de produção do bioetanol da cultura da batata-doce no Brasil (GONÇALVES NETO et al, 2011;MARTINS et al, 2012;SILVEIRA, 2008;TABORDA et al, 2015), na China (CAO et al, 2011;WANG et al, 2013), nos Estados Unidos (DUVERNAY; CHINN; YENCHO, 2013;SANTA-MARIA et al, 2011;ZISKA et al, 2009), no Uruguai (FERRARI;LAREO et al, 2013) e na Itália (MONTEFUSCO et al, 2014).…”