Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2009
Publication Date: 2/12/2009
Citation: Davis, J.P., Geller, D., Faircloth, W.H., Sanders, T.H. 2009. Comparisons of biodiesel produced from unrefined oils of different peanut cultivars. Journal of the American Oil Chemists' Society 86:353-361. Interpretive Summary: Biodiesel was prepared from the unrefined oils of eight different peanut cultivars to simulate on-farm peanut biodiesel production. Viscosity, density and propensity to crystallize were all determined, as these physical properties are important to fuel performance. Numerous differences were observed among cultivars and most importantly, increased concentrations of long chain, saturated fatty acids, namely C:24, were found to increase the propensity of the biodiesels to crystallize at low temperatures. This is undesirable as it can lead to engine damage, hence it is recognized that it would be desirable to decrease the concentrations of these fatty acids species, either through conventional breeding efforts and/or processing operations.
Technical Abstract: Biodiesels were prepared according to standard procedures from oils of eight commercially available peanut cultivars and compared for differences in physical properties important to fuel performance. Dynamic viscosity was measured from 100 to 15 ºC, and differences (P<0.05) among cultivars occurred more frequently at lower temperatures. Unlike data for the oil feedstocks, no meaningful correlations among biodiesel fatty acid profiles and either fuel viscosity or density were observed. Low temperature crystallization of the peanut biodiesels was measured via differential scanning calorimetry. Increased concentrations of long chain saturated fatty acids were associated with an increased propensity for low temperature crystallization, and the single fatty acid category most associated with low temperature crystallization was C:24. Tempering at 10 ºC followed by analysis of the soluble fractions (winterization), improved crystallization properties and confirmed the importance that long chain saturated fatty acids play in the final functionality of peanut biodiesel. Peanut data is also compared to data for canola and soy biodiesels, as these feedstocks are more common worldwide for biodiesel production. Overall, this work suggests that minimizing the concentration of long chain saturated fatty acids within peanut biodiesel, either through processing and/or breeding efforts would improve the quality of peanut biodiesel.