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United States Department of Agriculture

Agricultural Research Service

Title: Pyrolysis-Gas-Chromatography for the Analysis of Proteins: with Emphasis Onforages

Authors
item Reeves Iii, James
item Francis, Barry

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: September 1, 1998
Publication Date: N/A

Interpretive Summary: Forages and by-products are important materials for the feeding of ruminants (i.e, cattle). As such, considerable effort is expended on the determination of their composition. Pyrolysis (PY)is a procedure in which materials are heated in an inert atmosphere (No oxygen present). The heat causes the material to break down into simpler compounds whose composition depends on the starting materials. When connected to instruments capable of separating the compounds produced (gas/chromatography or GC) and then to an instrument capable of identifying the separated compounds (mass/spectrometry or MS), the procedure can be used to rapidly provide information on the composition of various materials. Pyrolysis has been shown to be very useful in the analysis of forages, particularly for the lignin and carbohydrate fractions. However, the same efforts do not show a similar abundance of information on the proteins present. Despite the fact that pyrolysis of isolated proteins produces an abundance of information, only small amounts of a few products are generally reported for forages. Reexamination of the subject indicates that many more productsare produced, but have been missed due to the low levels found, or because many do not contain nitrogen and are assumed to originate from other sources, such as lignin. In conclusion, results indicate that more information on proteins is present in pyrograms of forages than has been recognized.

Technical Abstract: Pyrolysis-gas-chromatography has been shown to be very useful in the analysis of forages, particularly for the lignin and carbohydrate fractions. However, the same efforts do not show a similar abundance of information on the proteins present, even for forages containing almost 30% protein. Despite the fact that pyrolysis of isolated proteins produces an abundance of information, only small amounts of benzeneacetonitrile, indole, methylindole,a methylphenol, dimethyl- or ethyl- pyrrole, and methanethiol are generally reported for forages. Reexamination of the subject indicates that many more products are produced, but have been missed due to the low levels found, or because many do not contain nitrogen and are assumed to originate from other sources, such as lignin. In conclusion, results indicate that more information on proteins is present in pyrograms of forages than has been recognized.

Last Modified: 7/28/2014
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