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Title:Evaluation of hydrothermal pretreatment and fermentation to improve lipid and ethanol production from corn germ meal
Author(s):Jia, Yuyao
Advisor(s):Singh, Vijay
Contributor(s):Rausch, Kent D.; Tumbleson, Mike E.; Dien, Bruce S.; Kumar, Deepak
Department / Program:Engineering Administration
Discipline:Agricultural & Biological Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
lipid producing energy crops
Abstract:Vegetable oil is extracted from oil rich seeds, such as soybeans. Genetic engineering of plants to accumulate oil in vegetative tissue is a potential future source of vegetable oil that promises increased land productivity and use of marginal lands. However, low concentrations of lipids in current engineered plant biomass samples makes extracting the oil challenging and expensive. The objectives of this work were to use hydrothermal pretreatment on oil bearing biomass for lipid enrichment and to investigate how lipid profiles changed during simultaneous saccharification and cofermentation (SSCF). Corn germ meal was chosen as a model for lipid producing energy crops because the later are in early developments and suitable samples were unavailable. To optimize liquid hot water (LHW) pretreatment, germ meal was pretreated at 20% (w w-1) solid loading with hot water at 160°C and 180°C for 10 and 15 min. Enzymatic hydrolysis on only pretreated solid was performed. Pretreatment enriched the oil concentration of solids 2.2 to 4.2 fold. The highest severity pretreatment applied, at 180°C for 15 min, had maximum oil concentration (9.7%), highest triacylglycerol (TAG) content of oil extracted from pretreated solids (71.6 %, w w-1 oil), and highest enzymatic recoveries of glucose and xylose (99.0% and 32.8%, w w-1 available glucose/xylose, respectively). LHW pretreatment improved lipid concentration in oil bearing biomass with little or no effect on lipid profiles. Having established the compatibility of LHW for oil recovery, the effect of fermenting the LHW pretreated biomass was evaluated for oil recovery and quality. To investigate ethanol production potential from LHW pretreated biomass and fate of oil during SSCF process, pretreated germ meal hydrolysate (combined liquid and solids) or solids (160°C and 180°C for 10 min) were fermented. Lipids were extracted from post fermentation broth or the solid residues obtained after centrifugation and convective drying of post fermentation broth (post fermentation solids). Lipid recovery efficiencies (LRE) were higher when oil was extracted from post fermentation broth compared to post fermentation solids. No differences were observed for LRE among all treatments. Lipid concentration of post fermentation solids increased 3.7 to 5.7 fold compared to oil present in raw germ meal. For all treatments, glucose and xylose profiles during SSCF were not different. SSCF of 180°C for 10 min pretreated solids gave highest lipid content of post fermentation solids of 12.9% (w w-1), highest TAG content of oil extracted from post fermentation broth and solids (29.3% and 26.3%, w w-1 oil, respectively), maximum ethanol conversion efficiency of 83.1% w w-1 theoretical ethanol production and maximum final ethanol titer of 32.4 g L-1. Fermentation increased lipid concentration of post fermentation solids and detrimentally affected lipid profiles. Fermenting solely pretreated solids instead of pretreated hydrolysate improved ethanol and lipid profiles.
Issue Date:2021-07-16
Rights Information:Copyright 2021 Yuyao Jia
Date Available in IDEALS:2022-01-12
Date Deposited:2021-08

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