Ethanol Production from Corn Fiber Separated after Liquefaction in the Dry Grind Process

Chinmay Kurambhatti,Kent Rausch,Vijay Singh,Mike Tumbleson,Deepak Kumar

doi:10.3390/en11112921

Abstract

Conversion of corn fiber to ethanol in the dry grind process can increase ethanol yields, improve coproduct quality and contribute to process sustainability. This work investigates the use of two physio-chemical pretreatments on corn fiber and effect of cellulase enzyme dosage to improve ethanol yields. Fiber separated after liquefaction of corn was pretreated using (I) hot water pretreatment (160 °C for 5, 10 or 20 min) and (II) wet disk milling and converted to ethanol. The conversion efficiencies of hot water pretreated fiber were higher than untreated fiber, with highest increase in conversion (10.4%) achieved for 5 min residence time at 160 °C. Disk milling was not effective in increasing conversion compared to other treatments. Hydrolysis and fermentation of untreated fiber with excess cellulase enzymes resulted in 33.3% higher conversion compared to untreated fiber.

Highlights

Bioethanol is the most commonly used renewable fuel in the transportation sector
Fiber contained 21.5% structural carbohydrates and 49.3% starch based polymers, which implied the hydrolysis and saccharification of fiber could yield a large amount of fermentable sugars
This study investigated various pretreatments and hydrolysis conditions (30 FPU/g fiber and 120 FPU/g fiber cellulase addition) to maximize ethanol yield from corn fiber

Summary

Introduction

Bioethanol is the most commonly used renewable fuel in the transportation sector. It can be produced from fermentation of sugars obtained from sugar crops, starch rich feedstocks or lignocellulosic biomass. The United States is the biggest ethanol producer. 10% w/w dry basis, respectively) are two sources of carbohydrates in corn, which can be hydrolyzed and fermented to ethanol. The corn starch is converted to ethanol through a series of steps, involving jet cooking, liquefaction and simultaneous saccharification and fermentation (SSF). Due to the high recalcitrance of corn fiber, it remains unconverted and ends up in DDGS, reducing its quality [1,2]

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