Feasibility of using free bioactive amines and amino acids for quality assessment and discrimination of animal meals

Abstract

The meat industry generates loads of residues, and its efficient utilization as animal meals is important from the environmental, economic, nutritional and safety points of view. The objective of this study was to investigate free amino acids and amines by ultra-performance liquid chromatography – UPLC™ in different types of animal meals and the feasibility of using them as quality and differentiation indices. Overall, 48 samples were analyzed; four types of meal [Feather meals (FM), meat & bone meals - bovine (MBM), pork/swine meals (SM), and Poultry meal (PM)] from 4 rendering plants; 3 different lots each). FM had higher protein and lower fat, whereas MBM) had higher ash, Ca and P (P < 0.05). Mercury was found in every sample (≤0.2 mg/kg). Total free amino acids were higher in MBM, and FM compared to the others (P < 0.05). FM had higher methionine, aspartic acid, and asparagine; SM had higher histidine (P < 0.05), which was not detected in MBM and FM. Phenylalanine was only found in MBM. Umami amino acids were prevalent in MBM; sweet amino acids in SM and FM; and bitter amino acids in SM and FM, thereby affecting palatability. PM had the widest diversity of amines (8), whereas MBM had the lowest (4). Higher amines levels were found in PM, and SM had the least (P < 0.05). Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) differentiated FM from MBM and from SM+PM, mainly by free amino acids and amines. The rendering plant D did not fit into any of the clusters, suggesting the poorest quality. Free amino acids and amines may be used as authenticity and quality indices for animal meals and rendering plants.