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Optimization of the in Situ Transesterification of Grain Sorghum (Milo) DDGS to Fatty Acid Methyl Esters and Fatty Acid Ethyl Esters
Author(s) -
Wyatt Victor T.,
Jones Kerby,
Johnston David B.,
Moreau Robert A.
Publication year - 2021
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1002/aocs.12470
Subject(s) - transesterification , chemistry , methanol , fatty acid methyl ester , biodiesel , ethanol , solvent , fatty acid , organic chemistry , fatty acid ester , glyceride , nuclear chemistry , catalysis
Distillers grains and solubles generated from the ethanol fermentation of grains contain acylglycerols (AG) that can be successfully converted to fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE), commonly known as biodiesel. However, when grain sorghum (milo) DDGS were used as a feedstock for in situ transesterification (IST) under the previously established optimal conditions for other AG‐bearing substrates, the yield plateaued at only 32.2% (corrected in this study to 24.2%). Several IST studies have reported significantly higher conversions of AG‐bearing substrates to FAME. Therefore, the goal of this IST study was to improve the conversion of the AG in milo DDGS to FAME and FAEE by varying the temperature of reaction, the concentrations of the base (sodium methylate, NaOMe), volume of methanol and ethanol, and the amount of moisture in DDGS. Methyl tert‐butyl ester was also evaluated as a co‐solvent intended to improve miscibility and reaction rate. Among these variables, the most effective change was an increase in temperature from 40 to 65 °C. The most successful reaction used a AG:NaOMe:MeOH molar ratio of 1.0:2.6:168.9. Those reaction conditions used 4.8 mmol NaOMe dissolved in 12.6 mL MeOH and resulted in a 79.8% conversion of AG to FAME.