Wheat Protein Determinations

The Grain Inspection, Packers and Stockyards Administration (GIPSA), Federal Grain Inspection Service (FGIS) uses Near Infrared Transmittance (NIRT) instruments to achieve its primary objective under the U.S. Grain Standards Act to ‘certify the quality of grain as accurately as practical’ as well as provide accurate information on storability, economic value and product yield. (7 U.S.C. Sec. 74(b)(2) and (b)(3) (C) and (E)). NIRT instruments are used to determine the amount of protein in wheat on a 12% moisture basis within grain presented for sale and as an assessment of quality that affects the value of the grain.

Official NIRT Instruments for Wheat Protein

  • Foss Infratec 1229 and Infratec 1241

Official Wheat Protein Calibration

For official wheat protein determinations, FGIS is using the Artificial Neural Network (ANN) calibration bundle WH050101. In addition, bundle WH0501xx may be used on instruments owned by customers of the official inspection system where the xx varies from 01 – 99 as long as the protein prediction model is WBPR0028 and the protein is displayed on a 12% moisture basis. The ANN calibration model is a global model based on over 30,000 samples developed by Foss in conjunction with FGIS, the Canadian Grain Commission, Cooperative Bulk Handling (Australia), and several NIR networks in Europe. The calibration may be purchased from Foss North America.

Wheat Protein ANN Calibration Data

In 2000, GIPSA provided Foss with data from each of the six wheat classes from the 1993 through 1999 crop years for the global ANN project. FGIS reviewed the calibration performance, determined that it performed at least as well as the approved calibrations in use during the evaluation, determined that it met the performance criteria in regulation §801.7(b) (1) under the U.S. Grain Standards Act, and adopted it for official wheat protein determinations in 2005.

The “Global” files were all scanned on the Foss model Infratec 1225, Serial Number (SN) 473 and include the crop year along with the reference protein value in addition to the spectra. There are 400 samples per wheat class for a total of 2400 spectra for the six classes of wheat grown in the United States. All spectra were collected under normal conditions (22 + 4 °C) and are from the 1993 through 1997 crop years.

Protein Range (12% moisture basis)
Wheat Class Number of Samples Minimum Maximum Spectra File
Durum 400 9.01 18.19 Durum Global (xls)
Hard White Wheat 400 8.47 16.81 HDWH Global (xls)
Hard Red Spring Wheat 400 9.27 19.00 HRS Global (xls)
Hard Red Winter Wheat 400 7.79 18.36 HRW Global (xls)
Soft Red Winter Wheat 400 8.18 12.10 SRW Global (xls)
Soft White Wheat 400 6.11 16.32 SWH Global (xls)

The “Temp” or temperature spectra were collected for use in the calibration to minimize the effects of changes in sample temperature on the protein determinations. The samples were scanned on the Foss model Infratec 1225, either SN 138 or SN 473, and are from the 1998 and 1999 crop years. All samples were scanned at 22 °C. Samples were then either conditioned to 0 °C prior to collecting the spectra (ID ending in C) or conditioned to 40 °C prior to collecting the spectra (ID ending in H). The instruments were in a room with a temperature maintained at 22 + 2 °C. There are a total of 712 samples representing all six wheat classes for a total of 1424 spectra. The Excel files contain the sample temperature, serial number, and the reference protein associated with each spectrum.

Protein Range (12% moisture basis)
Wheat Class Number of Samples Minimum Maximum Spectra File
Durum 87 8.69 18.03 Durum Temp (xls)
Hard White Wheat 92 8.87 15.76 HDWH Temp (xls)
Hard Red Spring Wheat 175 10.13 19.77 HRS Temp (xls)
Hard Red Winter Wheat 180 7.54 17.82 HRW Temp (xls)
Soft Red Winter Wheat 93 8.56 13.05 SRW Temp (xls)
Soft White Wheat 89 6.55 14.27 SWH Temp (xls)