A Comparative Analysis of Maillard-Derived α-Dicarbonyl Compounds and Advanced Glycation End Products in Fresh, Wet, Kibble, and Freeze-Dried Dog Foods

Abstract

Thermal processing of pet foods can lead to the formation of harmful Maillard reaction products (MRPs), which may compromise nutritional quality and pose health risks to companion animals. This study compared the levels of MRPs in 41 commercial dog foods, including fresh (n = 15), kibble (n = 13), wet (n = 10), freeze-dried (n = 2), and cold-pressed (n = 1) types. Acrylamide was found in only two kibble samples (40 and 76 µg/kg), while 5-hydroxymethyl-2-furfural and 2-furfural were not detected in any sample. Fresh foods had significantly higher lysine content (56 ± 13 g/kg dry matter [DM]) and lower lysine blockage (3.2 ± 0.7%) compared to kibble (23 ± 9 g/kg DM; 4.9 ± 1.2%) and wet foods (42 ± 14 g/kg DM; 3.0 ± 1.5%) (p < 0.05). Advanced glycation end products, Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL), were highest in wet foods (92 ± 36 mg/kg DM and 128 ± 39 mg/kg DM, respectively), indicating a greater thermal input (p < 0.05). α-Dicarbonyl compounds such as glyoxal and methylglyoxal were also significantly higher in wet samples (7.0 ± 2.5 and 15.8 ± 7.5 mg/kg DM, respectively) compared to fresh foods (2.8 ± 0.9 and 2.6 ± 0.8 mg/kg DM) (p < 0.05). This is the first report on the amounts of α-dicarbonyl compounds in commercial dog food. These findings emphasize the importance of carefully balancing food safety, nutritional quality, and processing conditions in pet food manufacturing.