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The pet food market is constantly expanding, and more and more attention is paid to the feeding of pets. Dry foods stand out and are often preferred due to their long shelf life, ease of administration, and low cost. In this context, dry foods are formulated from fresh meats, meat meals, or a mix of the two. These raw materials are often meat not fit for human consumption; they might be subject to contamination and proliferation of microorganisms which, by degrading the organic component, can lead to the formation of undesirable by-products such as biogenic amines. These nitrogenous compounds obtained by decarboxylation of amino acids can therefore be found in high-protein foods, and their ingestion in large quantities can cause intoxication and be harmful. This study aims at analyzing the possible presence of biogenic amines in three different formulations of chicken-based kibbles for pets: one obtained from fresh meat, one from meat meal, and one from a mix of the two. This study is also focused on the presence of free amino acids as they represent the key substrate for decarboxylating enzymes. Mass spectrometry (Q-TOF LC/MS) was used to analyze the presence of biogenic amines and free amino acids. The results show that fresh-meat-based products have a lower content of biogenic amines, and at the same time a higher quantity of free amino acids; on the contrary, meat-meal- and mix-based products have a greater quantity of biogenic amines and a lower concentration of free amino acids, suggesting that there has been a higher microbial proliferation as proved by the total aerobic mesophilic bacteria counts. It is therefore clear that fresh-meat-based kibbles are to be preferred when they are used for preparing dry pet food due to the lowest concentration of biogenic amines.

Dry pet food, made of fresh meats and especially meat meals, represents one of the main types of complete food available on the market by virtue of its practicality and long shelf life. The kibble production process includes mixed thermal and mechanical treatments that help to improve the palatability and durability of the final product but may have undesirable effects on nutrient bioavailability and digestibility. An analysis of the protein and lipid content of different dry pet food formulations, together with an in vitro digestibility analysis, can reveal which formulation can provide a more nourishing diet for pets. In this study, a quantitative and qualitative analysis was performed on three different formulations of chicken-based dry pet food, consisting of fresh meats, meat meals, or a mix of these two. The soluble protein concentration was determined by the Bradford assay, while the crude protein content was assessed through the Kjeldahl method. Quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS) was used to analyze the amino acid (AA) and lipid compositions. Finally, a gastric and small intestinal digestion simulation was used to determine the in vitro digestibility. The results show that dry pet food consisting only of chicken fresh meats has the highest content of soluble protein; it also contains more Essential AAs, Branched-Chain AAs, and Taurine, as well as a greater quantity of monounsaturated and polyunsaturated fatty acids. In addition, its in vitro digestibility was the highest, exceeding 90% of its dry weight, in agreement with the soluble protein content. These findings thus make the fresh-meat-based formulation a preferable choice as dry pet food.

The majority of dry pet food currently on the market is produced using fresh meats (FMs) and especially meat meals (MMs) as the main protein source. The transport and storage conditions of the raw materials, together with thermal and mechanical treatments in the case of MMs, may result in undesirable alterations of food products and their protein content. This study was conducted to analyze the protein component of three different kinds of raw materials used for dry pet food production, i.e., chicken, pork, and salmon. The quantitative analysis of the protein component was determined using the traditional Kjeldahl method and near-infrared (NIR) spectroscopy, and an alternative method, i.e., the Bradford assay, while the qualitative analysis was performed through SDS-PAGE, followed by Coomassie Blue staining. The amino acid (AA) profile was also evaluated by quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS). In addition, the digestibility was tested through in vitro gastric and small intestine digestion simulation. Statistical analysis was performed by the Student’s t-test, and data are reported as mean ± SEM, n = 10 (p < 0.05). The results showed that the MMs are lower in quality compared to FMs, both in terms of protein bioavailability and digestibility, having a lower soluble protein (SP) content (chicken MM = 8.6 g SP/100 g dry sample; pork MM = 6.2 g SP/100 g dry sample; salmon MM = 7.9 g SP/100 g dry sample) compared to FMs (chicken FM = 14.6 g SP/100 g dry sample; pork FM = 15.1 g SP/100 g dry sample; salmon FM = 13.7 g SP/100 g dry sample). FMs appear, therefore, to be higher-quality ingredients for pet food production. Moreover, the Bradford assay proved to be a quick and simple method to better estimate protein bioavailability in the raw materials used for dry pet food production, thanks to its correlation with the in vitro digestibility.