<i>In situ</i>pretreatment during distillation improves corn fiber conversion and ethanol yield in the dry mill process

Li, Xiujuan; Xu, Zhaoxian; Yu, Jianming; Huang, He; Jin, Mingjie

doi:10.1039/c8gc03447h

Cited by 25 publications

(21 citation statements)

References 33 publications

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“…In general, almost all cellulases, except BG-Pc, showed the reduced activity in ethanol cosolvents (Figure 1a), agreeing well with our previous studies. 7,21 In detail, the residual activities of EG-An and CBHII-Hi significantly decreased as the ethanol concentration increased. Notably, the CBHII-Hi lost almost all activity (3.8% residual activity) in 16% (v/v) ethanol, indicating that the ethanol molecules forcefully inhibit the activity of CBHII-Hi.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

Computer-Assisted Enzyme-Cocktail Approach Highly Improves Bioethanol Yield

Wang

Qiao

et al. 2021

ACS Sustainable Chem. Eng.

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Environmental concerns caused by fossil fuels and exponential energy demands have motivated the growth of the bioethanol industry, a promising renewable and green fuel. Enzymatic hydrolysis holds the promise to facilitate the most critical and rate-limiting hydrolysis steps in the cellulosic biomass conversion to ethanol process. However, a remaining challenge is how to rationally design the enzyme mixture without being labor-intensive and time-consuming. Herein, we reported a computer-assisted enzyme-cocktail (ComEC) design approach to improve feedstock utilization and ethanol yield. After screening of 17 structural and dynamics observables, two determinants, the hydration shell and water molecules in the active site, were identified from 20 molecular dynamics (MD) simulations of cellulase in 0–16% (v/v) ethanol and then used to direct the overall hydration-guided strategy and active-site inhibition-guided strategy for mixing the CBHI-CBHII-EG-BG cocktail. Notably, both strategies combining with fed addition technology achieved up to 5.8% improvement on ethanol yield compared to non-cellulase in situ corn fiber conversion. These results proved that the ComEC approach, based on a comprehensive molecular enzyme–solvent interaction landscape, allows intelligent design of enzyme-cocktail at the time–dosage resolution level and opens the gate of gaining higher production of bioethanol and even other renewable liquid fuels.

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Section: ■ Results and Discussionmentioning

confidence: 95%

Computer-Assisted Enzyme-Cocktail Approach Highly Improves Bioethanol Yield

Wang

Qiao

et al. 2021

ACS Sustainable Chem. Eng.

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“…Although less wastewater is produced due to biological detoxification rather than water washing and overliming, high citric acid dosage (4%) and reaction temperature (165°C) during pretreatment and too-long biodetoxification as strain growth and inactivation after detoxification influenced the economy of the process. Li et al (2019) used the combination of acid pretreatment with distillation to in situ pretreat whole stillage containing corn fiber. The pretreated stillage was recycled to the liquefaction step with the addition of cellulase, or hydrolyzed using cellulase and then recycled to the liquefaction step, or hydrolyzed using cellulase followed by C6/C5 sugar co-fermentation.…”

Section: Resultsmentioning

confidence: 99%

“…For example, Iram et al (2019) pretreated DDGS with dilute acid, and the yield of total reducing sugar (TRS) reached 0.382 g/g DDGS; besides TRS, furfural and HMF were also produced during the acid pretreatment. Li et al (2019) used the combination of acid pretreatment with distillation to in situ pretreat whole stillage containing corn fiber and recycled it to the liquefaction step, which improved the ethanol yield by 6.3% compared to the traditional process, and the cellulose conversion was 77.5%, but similarly, many inhibitors were also produced, which led to incomplete fermentation. Noureddini and Byun (2010) used dilute sulfuric acid to treat corn fiber and found that the highest yield of monosaccharides (63.1 g sugar/100 g corn fiber) was obtained when the pretreatment was conducted at 5% of biomass loading (w/w), 1.5% of sulfuric acid concentration (v/v), and 140°C, but the concentration of furfural in pretreatment liquor was also high (3.8 mg/ml) after pretreatment under the conditions.…”

Section: Introductionmentioning

confidence: 99%

A Detoxification-Free Process for Enhanced Ethanol Production From Corn Fiber Under Semi-Simultaneous Saccharification and Fermentation

Guo

Huang

et al. 2022

Front. Microbiol.

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Corn fiber, a by-product from the corn-processing industry, is an attractive feedstock for cellulosic ethanol because of its rich carbohydrate content (mainly residual starch, cellulose, and hemicellulose), abundant reserves, easy collection, and almost no transportation cost. However, the complex structure and components of corn fiber, especially hemicellulose, make it difficult to be effectively hydrolyzed into fermentable sugars through enzymatic hydrolysis. This study developed a simple and easy industrialized process without detoxification treatment for high-yield ethanol produced from corn fiber. Corn fiber was pretreated by dilute acid under the conditions optimized by Box-Behnken design (0.5% H2SO4 at 105°C for 43 min), and 81.8% of total sugars, including glucose, xylose, and arabinose, could be recovered, then the mixture (solid and hydrolysates) was directly used for semi-simultaneous saccharification and fermentation without detoxification, and ethanol yield reached about 81% of the theoretical yield.

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“…Although CF is mainly valorized in feeds, it can be also a useful substrate for bioethanol production [17]. Recently, intense research efforts have been made to develop novel and efficient processes for the conversion of CF into ethanol, which could highly improve the ethanol yield in a corn-to-ethanol facility [18][19][20][21]. In addition, CF could serve as a raw material for the production of other high-value bio-products beside ethanol, if it is utilized in a biorefinery process allowing the efficient and selective fractionation of valuable CF components, such as hemicellulosic sugars.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Enzymatic and Acidic Fractionation of Corn Fiber for Glucose-rich Hydrolysate and Bioethanol Production by Candida boidinii

Fehér

Bedő

Fehér

2021

Period. Polytech. Chem. Eng.

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Corn fiber is a by-product of the corn wet milling process and a promising raw material to produce bioethanol in a bio-refinery process. In this study, enzymatic and acidic fractionations of corn fiber were compared with particular attention to produce glucose-rich hydrolyzates. The acidic fractionation contained two, sequential, sulphuric acid-catalyzed, hydrolysis steps based on our previous study. In the enzymatic fractionation process, corn fiber was pre-treated by soaking in aqueous ammonia (18.5 % (w/w) dry matter, 15 % (w/w) ammonia solution, 24 hours) and then hydrolyzed by using Hemicellulase (NS 22002) enzyme cocktail. The cellulose part of the solid residues obtained after the acidic and enzymatic fractionation processes was enzymatically hydrolyzed by using Cellic Ctec2 and Novozymes 188 (12.5 % (w/w) dry matter, 50 °C, 72 hours). Cellulose hydrolysis after the acidic and enzymatic fractionation resulted in a supernatant containing 64 g/L and 25 g/L glucose, respectively. Therefore, ethanol fermentation experiments were performed in Separated Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF) configurations after the acidic fractionation of corn fiber. SHF configuration was found to be more advantageous regarding the achievable ethanol yield. Although the fermentation with Candida boidinii NCAIM Y.01308 was accomplished within longer time (43 hours) compared to Saccharomyces cerevisiae (5 hours), the achieved ethanol yields were similar (79%) during the SHF process. It was concluded that acidic fractionation is more efficient to produce glucose-rich hydrolyzate from corn fiber compared to enzymatic fractionation, and Candida boidinii is suitable for ethanol fermentation on the glucose-rich hydrolyzate.

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In situpretreatment during distillation improves corn fiber conversion and ethanol yield in the dry mill process

Abstract: The in situ pretreatment and in situ conversion of corn fiber increased cellulose conversion and the overall ethanol yield.

Cited by 25 publications

References 33 publications

Computer-Assisted Enzyme-Cocktail Approach Highly Improves Bioethanol Yield

Computer-Assisted Enzyme-Cocktail Approach Highly Improves Bioethanol Yield

A Detoxification-Free Process for Enhanced Ethanol Production From Corn Fiber Under Semi-Simultaneous Saccharification and Fermentation

Comparison of Enzymatic and Acidic Fractionation of Corn Fiber for Glucose-rich Hydrolysate and Bioethanol Production by Candida boidinii

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