Effect of microwave heating on physicochemical properties, protein composition and structure, and micromorphology of camel and bovine milk samples

This study aimed to investigate the effect of microwave heating (0, 100, 300, 500, and 700 W; 2 min) on the physicochemical properties, protein composition, and structure and micromorphology of camel and bovine milk samples. Results showed that the physicochemical properties, including pH, protein content, ash content, and soluble solids of both milk samples, decreased after 300 W microwave processing (P < 0.05). The serum albumin and immunoglobulin levels of bovine milk decreased after 300 W processing (P < 0.05), and camel milk whey proteins were more heat resistant than bovine milk proteins. The decreased relative content of κ-casein and the absence of β-lactoglobulin were also found in camel milk during 300–700 W processing (P < 0.05). Besides, microwave heating after 300 W induced a conformational transformation and reduced the protein stability of both milk samples. The particle size and scanning electron microscopy images confirmed that the protein structure was changed after 300 W processing. These results indicated that microwave heating at 300 W for 2 min was beneficial to the retention of nutrients (proteins and soluble solids) and the maintenance of protein stability in both milk samples.