Measuring Protein Content, are there differences in Canadian and U.S. methods?
Yes, there are some differences, as well as many similarities.
An important difference is in the reporting of test results for wheat. In Canada, protein for wheat is reported on a 13.5% moisture basis and in the U.S. protein for wheat is on a 12% moisture basis. This difference in moisture will result in U.S. protein being reported as approximately 0.2% higher than the equivalent Canadian value. In other words, in Canada a 13.5% protein on 13.5% moisture basis is equivalent to a 13.7% protein on a 12% moisture basis in the U.S.
For the most accurate conversion, the following equation for converting protein:
X = (P/100-12) x 100 x (100-PX/100)
– X = protein content at moisture basis other than 12%
– P = protein content determined at a 12% moisture basis
– PX = the moisture basis specified by the applicant
In terms of barley, the moisture basis for protein in the U.S. and Canada is reported on a dry matter basis, as such there is no adjustment required.
Both the Canadian Grain Commission (CGC) and U.S. Federal Grain Inspection Service (FGIS) will report protein on an alternate moisture basis upon request using simple mathematical calculations to convert results.
The CGC in Canada and FGIS in the U.S. use the same reference method for analyzing the protein content of grains and oilseeds which is combustion nitrogen analysis (CNA). The CNA laboratory supports the NIRT instruments that are used for official testing in Canada and the U.S. The CNA reference method incinerates samples and captures and measures the nitrogen content. This is then converted to protein content. FGIS and CGC use CNA method AOAC 992.23, or the equivalent method AACC 46-30.