Soluble protein content assessment in dry pet food raw materials: Comparison between fresh meat and meat meal formulations

Long shelf life and ease of use make dry pet food a popular choice among pet owners, inasmuch as it represents themajority of pet food on the market today. Two kinds of raw materials are commonly employed for the production of drypet food, namely fresh meats (FMs) and particularly meat meals (MMs). These raw materials, before coming onto themarket as dry pet food, undergo production processes, transportation, and, when it comes to MMs, industrialtransformations, which may result in unwanted modifications of such ingredients, especially as far as their proteincontent is concerned. The goal of this study is to analyze the protein content of the raw materials regularly used in theproduction of dry pet food. Different formulations of white, red, and fish FMs and MMs have been prepared andanalyzed. The protein concentration of both FM and MM mixes was assessed by the Bradford assay, with the aim beingto evaluate the soluble protein content, which represent also a convenient digestibility index. Subsequently, the qualityof proteins was evaluated through the characterization of the electrophoretic profile assessed by SDS-PAGE followedby staining with Coomassie Blue dye. The results proved that the formulations made of FMs, compared to the onesbased on MMs, have a higher soluble protein content and a better-defined protein profile, thus making the former thebest choice as raw materials for dry pet food production.