Chemical profile, energy values, and protein molecular structure characteristics of biofuel/bio-oil co-products (carinata meal) in comparison with canola meal.

To our knowledge, little information exists on nutritive values and molecular structural characteristics associated with protein biopolymers of carinata meal from biofuel and bio-oil processing. The objectives of this study were to investigate (1) chemical compositions; (2) protein and carbohydrate subfractions partitioned by the Cornell Net Carbohydrate and Protein System (CNCPS); (3) truly digestible nutrients and energy values; (4) protein conformation spectral characteristics using the ATR-FT/IR technique; and (5) the correlation between protein intrinsic structural features and nutrient profiles of carinata meal in comparison with conventional canola meal as references. The results showed that carinata meal was higher (p < 0.05) in soluble crude protein (SCP, 55.6% CP) and nonprotein nitrogen (NPN, 38.5% CP) and lower in acid detergent insoluble crude protein (ADICP, 1.3% CP) compared to canola meal. Although no differences were found in CP and carbohydrate (CHO) contents, CNCPS protein and carbohydrate subfractions were different (p < 0.05) between carinata meal and canola meal. Carinata meal has similar contents of total digestible nutrient (TDN) and predicted energy values to canoal meal (p > 0.05). As for protein spectral features, much greater IR absorbance in amide I height and area as well as α-helix and β-sheet height for carinata meal by 20-31% (p < 0.05) was found compared with canola meal; however, results from agglomerative hierarchical cluster analysis (CLA) and principal component analysis (PCA) indicated these two meals could not be distinguished completely within the protein spectrum (ca. 1728-1478 cm(-1)). Additionally, close correlations were observed between protein structural parameters and protein nutrient profiles and subfractions. All the comparisons between carinata meal and canola meal in our study indicated that carinata meal could be used as a potential high-protein supplement source for ruminants. Further study is needed on more information associated with nutrient degradability, utilization, and availability of carinata meal to ruminants for its better and effective application in animal industry.