ARS | Publication request: Fatty acid profiling of soybean cotyledons by NIR spectroscopy

Submitted to: Soybean Biotechnology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2007
Publication Date: N/A

Technical Abstract: The research was conducted to quantify the five fatty acids in soybean (Glycine max) cotyledons using near-infrared (NIR) spectroscopy. Soybean cotyledon samples were dried and ground. A 250-mg sample was scanned in the visible and NIR regions (400 to 2500 nm), and diffuse reflectance was recorded. Samples were also analyzed by gas chromatography (GC) for palmitic, stearic, oleic, linoleic, and linolenic acids and total oil. GC data were expressed as actual concentration and proportion of total oil then regressed against spectral data to develop calibration equations. Calibration statistics indicated that four of the five fatty acids could be predicted accurately by NIR spectroscopy; the fifth fatty acid could be determined by subtraction. Principal component analysis revealed that spectral variation in this population was primarily due to chlorophyll absorbance in the visible region, so the spectra were trimmed to omit the visible region. A second set of equations was developed exclusively from NIR spectra (1100-2500 nm). Equations based only on NIR spectra were slightly more precise than equations based on vis+NIR spectra. Principal component and partial least squares analysis revealed that at least 90% of the spectral variation in the NIR region was unrelated to fatty acid, though variation from fatty acid. This research provides an NIR method for complete fatty acid profiling of soybean cotyledons. A complete write-up of this research may be found in the November 2006 issue of Applied Spectroscopy.