443Whole, cracked and flaked soybeans were stored under a variety of conditions. After extraction with hexane, the crude oils were degummed in the laboratory, and the nonhydratable phospholipid (NHP) content was estimated from the phosphorus content of the degummed oil. Results showed that four interrelated factors promote NHP formation. These include (i) moisture content of beans or flakes entering the extraction process; (ii) phospholipase D activity; (iii) heat applied to beans or flakes prior to, and during, extraction; (iv) disruption of the cellular structure by cracking and/or flaking. Results from this study suggest that NHP formation can be minimized by control of the moisture of beans and/or flakes entering the extraction process, inactivation of phospholipase D enzyme, and optimizing temperatures during the conditioning of cracked beans or flakes.

A user-interactive computer-assisted Fourier transform infrared (FTIR) method has been developed for estimation of free fatty acids (FFA} in vegetable oil samples by deconvolution of the infrared {IR) absorbances corresponding to the triglyceride ester and FFA carbonyl bonds. Peak areas were used to determine FFA as a percentage of the total carbonyl areas in weighed standards of refined, bleached, deodorized soybean oil containing from 0 to 5% added oleic acid. These data for percent FFA by FTIR were compared to corresponding FFA data obtained by two titration methods--the AOCS Official Method Ca 5a-40 and the Official Method with a slight modification. Correlation coefficients were 0.999 for the Ca 5a-40, 0.999 for the modified and 0.989 for the FTIR methods. FFA in samples of crude soybean oils extracted from damaged beans {0.5 to 2.1% FFA) were measured by FTIR and compared to data obtained by titration of the same samples {correlation coefficient, 0.869}.

A computer-assisted method has been developed for estimation of isolated trans unsaturation using the peak area of the trans absorbance band at 966 cm-1 from FTIR spectra of fatty acid methyl esters. Peak areas were used to determine the trans content of weighed standards containing from 0 to 100% methyl elaidate and of hydrogenated soybean oil samples containing up to 36% trans unsaturation. These data for percent trans by FTIR were compared to corresponding data obtained by capillary gas chromatography and the AOCS Official Method 14-61. Determination of isolated trans composition in oils using peak areas gave values with the smallest standard deviation for weighed standards and values within 4% of those obtained by capillary gas chromatography and the AOCS Official Method for hydrogenated samples.Various infrared (IR) spectrophotometric methods for estimation of trans unsaturation in lipids have been suggested and routinely used in the fat industry for many years (1-4). These methods are based on measuring peak height at 965-966 cm 1 from a manually drawn or zero adjusted (where possible} baseline and comparing this absorbance value to that of standards or to other related absorbances.Recent advances in equipment technology have incorporated computer capabilities into FTIR instruments allowing manipulations of the IR spectra, i.e., enlargement, isolation of selected regions, and calculation of peak areas, all of which can be outputted to a plotter or a printer. If output is to a printer, an IR absorbance grid suitable for manual measurement of peak height differences in absorbance units is not normally obtained. Standard peak height procedures for estimating isolated trans unsaturation, therefore, become more tedious and less accurate.A simple computer-assisted procedure has been developed for determining isolated trans unsaturation in fatty acid methyl esters (FAME) based on integration of the area of the absorbance peak due to trans unsaturation. Areas were obtained with a Fourier transform infrared (FTIR) instrument and used to determine percent isolated trans in weighed mixtures of methyl elaidate and methyl oleate (0-100% elaidate) and in six partially hydrogenated soybean oil samples. These data were compared to corresponding data determined by the AOCS Official Method (peak height) and by capillary gas chromatography. MATERIALS AND METHODSMethyl oleate (cis-9-octadecenoate) and methyl elaidate (trans-9-octadecenoate) were purchased from Hormel