Production of Fatty‐Acid Methyl Esters Via the In Situ Transesterification of Grain Sorghum Bran and Sorghum Distiller's Dried Grains and Solubles

The acylglycerols (AG) in sorghum bran and distiller’s dried grains and solubles (DDGS) from sorghum postfermentation have been converted to fatty-acid methyl esters (FAME) using an in situ transesterification method. The reactions were conducted at 25 or 40 C by incubating 8 g of feedstock, containing 1.3–2.4 mmol AG, in a solution of 2.4 or 4.8 mmol of NaOMe dissolved in 6.4 or 12.8 mL MeOH. The experimental results confirmed that reducing the moisture to approximately 2% (w/w) within the feedstock was necessary for the reaction to proceed. All of the reactions were monitored using high-performance liquid chromatography and all performed better at 40 C than at 25 C. The most successful reactions used a AG:NaOMe:MeOH molar ratio of 1.0:2.0:131.7. Those reactions used 4.8 mmol NaOMe dissolved in 12.8 mL MeOH producing up to 98.3% FAME when sorghum bran was used as the feedstock. When DDGS from sorghum were used as the feedstock, the yield averaged 32.2% under the previously established optimal conditions.