The Rapid Preparation of Pet Food for Amino Acid Analysis

Introduction

Protein plays a major role in the manufacturing process of wet and dry pet food commodities. Not only does the quality and amount of protein affect the overall cost of production, it also influences consumer interest in the product. One way to assess the quality of a dietary protein is to examine the total amino acid content of the sample by means of amino acid hydrolysis. Classically, proteins are hydrolyzed under acidic or basic conditions for upwards of 24 hours. This treatment breaks the peptide bonds between amino acid residues in proteins, ultimately allowing for the identification and quantification of each amino acid. Long reaction times are required because of slow volumetric heating, erratic heat gradients, and inconsistent reaction yields, characteristic of conventional heating.

Microwave-assisted reactions have been highlighted as an approach to significantly decrease hydrolysis times and increase reaction yields and reproducibility. CEM’s Discover Prep^TM microwave-based sample preparation system offers an excellent path for the optimization of protein hydrolysis reactions. Herein, wet and dry pet foods were subjected to traditional acid hydrolysis as well as optimized microwave-assisted hydrolysis conditions. The amino acid content of each sample was determined via pre-column derivatization using the Waters AccQ-Tag™ Ultra Derivatization Kit, followed by LC-PDA analysis at 260 nm. Overall, the Discover Prep results were comparable to the traditional hydrolysis with key benefits, including shorter reaction times, cleaner hydrolysates, and quicker time to analysis.