Analysis of oil content of sunflower seed by wide‐line NMR

The wide‐line nuclear magentic resonance (NMR) analyzer is routinely used to determine the oil content of sunflower seed by plant breeders. This technique is now under consideration as the official method for the domestic trading of sunflower seed. A study of the effect of depth (volume) of sunflower seed in the NMR 130 ml sample tube showed that between a depth of 30–75 mm (23.5–62.5 g seed) the NMR response was uniform, but beyond 75 mm, the response rapidly decreased. Oil analysis of 10 sunflower seed samples showed that coefficient of variation (C.V.) was lower with a 130 ml sample tube (C.V. 0.4%) than with a 34 ml tube (C.V. 0.8%). As the temperature of the sample was increased 1C, the instrument response decreased by 0.4%. Analysis of sunflower seed with 31–71% linoleic acid contents analyzed 0.1% higher for each 1% decrease in linoleic acid. Data show that linoleic acid content of NMR sunflower seed standard is important in NMR total oil analysis. Results of this study showed that the sample of sunflower seed for total oil analysis by NMR should be contained at least within the bottom 70 mm of the 130 ml sample tube, and NMR response of the standard calibration seed and sample being analyzed should be read at the same temperature, and their fatty acid compositions should be similar.