Application of FT/IR-ATR vibrational spectroscopy to reveal protein molecular structure of feedstock and co-products from Canadian and Chinese canola processing in relation to microorganism bio-degradation and enzyme bio-digestion.

The principal objective of this study was to apply FT/IR-ATR vibrational spectroscopy to inspect the relationship between rumen dry matter (DM) and protein degradation, rumen undegraded protein (RUP) intestinal digestion and processing induced protein molecular structure changes in feedstock (canola oil seeds) and co-products (canola meal) from bio-oil processing from different crushing plants in Canada and China. The rumen DM and protein degradation, rumen undegraded protein intestinal digestion and protein molecular structure affected by bio-oil processing were examined using in situ, three step in vitro digestion and Fourier transform infrared (FT/IR) molecular spectroscopy techniques, respectively. The results showed that the protein molecular structure; α-helix height and α-helix to β-sheet height ratio had a close association with rumen DM and protein degradation and rumen undegraded protein intestinal digestibility. Multiple regression analyses showed that protein β-sheet height and α-helix to β-sheet height ratio spectral intensity can be used to predict rumen DM and protein degradation, while intestinal digestibility of rumen undegraded protein can be predicted by α-helix height and β-sheet height. In conclusion, the co-product canola meal from bio-oil processing is a good source of intestinally digestible protein. Rumen DM and protein degradation and intestinal digestibility of rumen undegraded protein are related to the protein molecular structures of the co-products affected by changes during bio-oil processing.