Temporal, biochemical and structural factors that influence beef quality measurement using near infrared spectroscopy

This study included simultaneously measured pre and post-rigor meat quality indicators and attributes, using near infrared (NIR) spectroscopy and reference methods, to understand the temporal, biochemical and structural factors that influence beef quality and use this knowledge to build calibrations for measurement of meat quality using NIR. Eighty beef M. longissimus lumborum (LL) were measured from early pre-rigor (pH, glycogen concentration, and temperature) through to completion of post-rigor ageing (pH, shear force, and water holding capacity (WHC)). To create a range in the attributes, the LLs were subjected to various pre-rigor treatments, including electrical stimulation, restraint wrapping and cooling temperature (5°C, 15°C, or 35°C). Alongside the reference quality measurements and throughout the pre and post-rigor period, the LLs were measured with a diode array NIR spectroscopy system. NIR reflectance measurements were shown to be correlated to reference measurements of pre and post-rigor pH (R(validation)(2)=0.84), pre-rigor glycogen content (R(validation)(2)=0.70), post-rigor shear force (R(validation)(2)=0.58) and post-rigor WHC (R(validation)(2)=0.68). The shape of the NIR and reference plots over time and the ability of NIR to correctly measure differences in treatments indicated that NIR was not merely measuring changes that occur over time, but was measuring specific biochemical and physical changes, most likely changes in glycolytic metabolites, muscle shortening and/or proteolysis. Accounting for the reference method variance showed NIR measurement accuracy to be as good as or slightly better than that of the reference method.