A number of analytical methods for constituents commonly measured in distillers dried grains (DDG) are practiced in laboratories serving the agricultural sector.
A large interlaboratory variability among results has been observed in the industry. Methods for moisture, crude fat, and crude fibre are empirical, thus part of this variability can be attributed to the use of different methods of analysis.
A study was organized and supported by the American Feed Industry Association (AFIA), the Renewable Fuels Association (RFA), and the National Corn Grain Association (NCGA) to evaluate the efficacy, applicability, and the intralaboratory variation of a number of methods for moisture, crude protein, crude fat, and crude fibre in DDG with solubles (DDGS).
A second study was undertaken to assess existing interlaboratory variation of the same methods in 23 laboratories.
Based on the results of these studies, the sponsoring associations established recommended reference methods for use in commercial trade of DDGS (see table).
Constituent | Studied methods | Recommended method |
Moisture | AOAC1 930.15, AOAC 934.01, AOAC 935.29, AOAC 2003.06, NFTA2 2.2.2.5 | NFTA 2.2.2.5 |
Crude protein | AOAC 990.03 AOAC 2001.13 | AOAC 990.03 AOAC 2001.11 |
Crude fat | AOAC 945.16, AOAC 954.02, AOAC 2003.05, AOAC 2006.06 | AOAC 945.16 |
Crude fibre | AOAC 978.10 AOCS3 Ba 6a-05 | AOAC 978.10 |
The recommendations are based on inter-laboratory studies in which Denmark-based analytical solutions provider Foss was involved, participating in the trials and supplying analytical solutions.