Performance of a Handheld MicroNIR Instrument for Determining Protein Levels in Sorghum Grain Samples.

Area of Science:

• Agricultural Science
• Analytical Chemistry
• Spectroscopy

Background:

• Near-infrared (NIR) spectroscopy is a valuable tool for assessing cereal grain quality.
• Accurate protein content analysis is crucial for sorghum grain quality evaluation.
• Benchtop instruments provide a baseline for performance comparison.

Purpose of the Study:

• To compare the efficacy of a handheld NIR instrument (VIAVI MicroNIR OnSite-W) against a benchtop instrument (Perten DA-7250) for determining intact sorghum grain protein content.
• To assess the suitability of the MicroNIR for on-site or cost-effective sorghum protein screening.

Main Methods:

• Developed parallel NIR calibrations using both Perten DA-7250 and VIAVI MicroNIR instruments.
• Collected spectral data from 59 sorghum grain samples simultaneously with both instruments.
• Validated cross-validated calibration models using 33 independent test samples.

Main Results:

• The Perten DA-7250 achieved high accuracy (R²=0.94, RMSEP=0.52%, RPD=4.13) for predicting protein content in the test set.
• The VIAVI MicroNIR demonstrated acceptable performance (R²=0.87, RMSEP=0.76%, RPD=2.74), though less accurate than the DA-7250.
• The MicroNIR's performance was deemed suitable for screening sorghum protein levels in field or cost-sensitive applications.

Conclusions:

• While the benchtop DA-7250 provided superior accuracy, the handheld MicroNIR is a viable tool for screening sorghum protein content.
• The MicroNIR offers a practical alternative for field-based analysis or when budget constraints limit the use of benchtop equipment.
• This study validates the potential of portable NIR technology for on-farm or in-process quality assessment of sorghum.