Using advanced vibrational molecular spectroscopy (ATR-Ft/IRS and synchrotron SR-IMS) to study an interaction between protein molecular structure from biodegradation residues and nutritional properties of cool-climate adapted faba bean seeds

Abstract

The objective of this study was to use advanced vibrational molecular spectroscopy (ATR-Ft/IRS) to study an interaction between legume protein molecular structure from biodegradation residues and nutritional properties of newly developed genotypes of cool-climate adapted faba bean seed with low and normal tannin levels grown in western Canada. Protein molecular structures including amide I, II areas and peak heights, α-helix and β-sheet peak heights in rumen biodegradation residues were determined by using attenuated total reflectance Fourier transform infrared molecular spectroscopy (ATR-FTIR). The nutritional properties were determined which included chemical and nutrient profiles, in situ rumen degradation kinetics, rumen protein degradation, and intestinal protein digestion in the newly developed genotypes of faba bean seeds with low and normal tannin levels. The results showed that the spectral intensity of faba bean varieties with a normal tannin level in rumen biodegradation residues was greater (P < 0.05) than that with a low tannin level. The spectral intensity of amide I, II areas and peak heights, α-helix and β-sheet peak heights in all genotypes (except the variety of Snowdrop) in biodegradation residuals of faba bean seeds had a unique pattern with increasing first and then decreasing with the increasing of rumen incubation time. The molecular structures of protein (α-helix, ratio of α-helix to β-sheet height and amide I to II area, R² > 0.6) were associated with in situ degradation kinetics - soluble (S) and potential degradable fractions (D) and rumen protein degradation- bypass or undegraded protein (BCP or RUP). The molecular spectral parameters in the FTIR fingerprint region didn't form cluster among different genotypes in residual faba bean seeds in 12 h and 24 h incubation, which indicate they had similar protein molecular structures after incubation. In conclusion, there was an interaction between protein molecular structure from biodegradation residues and nutritional properties of newly developed cool-climate adapted faba bean seeds with normal and low level of tannin. The cool-climate adapted genotype had an impact on the protein molecular structure, and the protein utilization and metabolism were predictable from protein spectral molecular structures after rumen biodegradation with ATR-Ft/IRS spectroscopy.

Keywords: Biodegradation residues of faba legumes; In situ degradation kinetics; Intestinal protein digestion; Protein molecular structure; Rumen protein degradation; Vibrational molecular spectroscopy.