Fast Chromatography of Pulse Triacylglycerols

Authors: Byrdwell, W Craig; KOTAPATI, HARI - University Of Maryland; Goldschmidt, Robert

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2022
Publication Date: 11/22/2022
Citation: Byrdwell, W.C., Kotapati, H.K., Goldschmidt, R.J. 2022. Fast Chromatography of Pulse Triacylglycerols. Journal of the American Oil Chemists' Society. 100:25-43. https://doi.org/10.1002/aocs.12665.
DOI: https://doi.org/10.1002/aocs.12665

Interpretive Summary: There is a trade-off and compromise between complex methods of analysis that yield extremely detailed results but take a long time, versus simpler methods of analysis that give less information but are faster and give sufficient information for a high volume of samples. We developed a fast method for separating and analyzing the oils in legume seeds, called pulses. Using this fast method we were able to determine the individual components in the oils of ten pulses: baby lima beans, black beans, black-eyed peas, butter beans, cranberry beans, garbanzo beans, green split peas, lentils, navy beans, and pinto beans. The compositions of pulses clustered into three groups having similar compositions. There is very little data for the oils from pulses, and this report provides new information about the nutritional characteristics of these ten pulse oils. These results are correlated with another report by colleagues of a different class of molecules in these pulses, called oligosaccharides. Our new data combined with previous data provide a better overview of the complete compositions of nutrients in the seeds of legumes.

Technical Abstract: A short 10-minute ultra high performance liquid chromatography (UHPLC) method was used for separation and lipidomic analysis of triacylglycerols (TAGs) in ten pulses: baby lima beans, black beans, black-eyed peas, butter beans, cranberry beans, garbanzo beans, green split peas, lentils, navy beans, and pinto beans. The lipids extracted using chloroform/methanol averaged 1.9-2.7% across all pulses except garbanzo beans, which gave 6.2% lipids. TAGs were analyzed using dual parallel mass spectrometry (LC1MS2), areas were integrated using LipidSearch 4.2 software, and a percent relative TAG composition was calculated. Fatty acid response factors were calculated by comparison to calibrated GC-FID, which were used to calculate a response-factor adjusted TAG composition. Principal component analysis revealed that the pulses separated into three clusters, which were further highlighted using hierarchical cluster analysis. A subset of TAGs was quantified using calibration curves made from alternating sets of regioisomers in the non-linear high concentration range (~2.5 nMol/mL to ~300 nMol/mL). A linear calibration curve for the sum of tocopherols detected by fluorescence was constructed with a coefficient of determination, r2, > 0.99 for low concentrations (0.50 µg/mL to 50 µg/mL), but tocopherols in pulses appeared to be inefficiently extracted. TAG regioisomers were quantified based on a Critical Ratio (CR), [AA]+/[AB]+, interpolated between the CRs of two pure regioisomer standards taken from alternating calibration standards. TAG mole percent relative compositions are reported for the first time for mostpulses and the compositions are given with more detail and specificity than previously reported.