Generation of Olfactory Compounds in Cat Food Attractants: Chicken Liver-Derived Protein Hydrolysates and Their Contribution to Enhancing Palatability

The present study investigated the impact of four chicken liver protein hydrolysate-based cat food attractants on palatability. Aroma compounds were analyzed in these attractants, which were subsequently sprayed onto four different types of cat foods. Results revealed that CF4 exhibited the highest intake ratio and the first choice ratio, followed by CF2 sample. Orthogonal partial least-squares discriminant analysis (OPLS-DA) demonstrated significant differences among 50 volatile compounds identified from the four cat foods. Using variable importance in projection (VIP) values, we selected 17 key flavor compounds responsible for distinguishing between the four cat foods. Peptides with a molecular mass <180 Da showed correlation with nonanoic acid and cedrol, while those >3000 Da correlated with hexanoic acid ethyl ester. Regression coefficients (RCs) calculated from partial least-squares regression (PLSR) results showed positive correlations between compound content and palatability for six compounds, whereas negative correlations were observed for ten compounds. Validation experiments confirmed that nonanal, 2-propylpyridine, and 3-octen-2-one enhanced palatability and correlated with peptides ranging from 180 to 500 Da; conversely, nonanoic acid ethyl ester and 3-methyl-pentanoic acid reduced palatability and correlated with peptides ranging from 1000 to 3000 Da.