NMR Measurement of Intra-Muscular Fat

Summary

The time-domain NMR system “Oscar 2” was shipped to the University of New England, Armidale, NMR where it was used to measure lamb loin samples for fat content. The practical work was completed June 5-7, 2019. Data was collected at 12.3 MHz on lamb longissimus dorsi samples from 239 lambs as part of the ALMTech programme. The corresponding intramuscular fat (IMF) data were also acquired (by an laboratory infra-red method) and used to build predictive models that had a predictive correlation of 0.84 (r2= 0.71) over a range of 3-8% IMF with a predictive error of 0.5%.

This error was similar to the uncertainty in the NMR fit parameter and primary indicatory p2f. The prediction models are only dependent on the NMR parameter p2f, which is the amplitude of the short exponential decay. The uncertainty in IMF prediction is most likely due to an oscillation at the beginning of the CPMG decay, which is most likely caused by an instrument artefact that can be fixed. This would potentially remove instrument error as a significant source of variance. The performance of the predictive model reported here performs similar to, if not better than the models reported from a previous AgResearch project. However, different models are required, possibly because of the species involved.

The methods used were based on prior work conducted for MLA – P.PSH.0878. For context on the NMR measurement and the equipment refer to Appendix 1.