Analysis of oil content of soybeans by wide‐line NMR

Samples of soybeans, ranging from single seed to 25 g, were scanned by NMR and then gravimetrically analyzed for oil content. High positive correlations of NMR and oil for single seed (r=0.998) and for 25‐g samples (r=0.999) were found. Single 30‐sec NMR scans gave accurate estimates of the oil content of sobean seeds which had been dried to less than 4% moisture content. Fifteen samples of known percentage composition, created by mixing calculated weights of soybean oil with oven dry soybean meal (made lipid‐free by petroleum ether and by carbon tetrachloride extraction), were scanned by NMR. These 15 samples, starting at 2% oil and increasing by increments of 2% oil up to 30%, had a linear relationship of NMR readouts with these known percentages of oil. These results indicate that wide‐line nuclear magnetic resonance spectroscopy is an accurate, rapid and nondestructive tool for determining the oil content of soybean seeds. Since NMR scanning of seed does not alter its composition or destroy its viability, this method of oil analysis could accelerate the development of new soybean strains.