Major whey proteins in donkey's milk: effect of season and lactation stage. Implications for potential dietary interventions in human diseases

According to current literature, donkey's milk has been suggested as a hypoallergenic substitute in children affected by cow's milk protein allergy as well as a promising nutraceutical for aged people. However, the biologically active components of donkey's milk have not yet completely elucidated. In this framework this study is aimed at measuring α-lactalbumin (α-LA), β-lactoglobulin (β-LG), and lysozyme (LYS), the principal whey proteins in donkey's milk, in relation to lactation stage and production season. Analysis were performed by reversed-phase high-performance liquid chromatography. α-LA, β-LG, and LYS resulted to be affected by lactation stage (P < 0.01) and production season (P < 0.01). Overall, the protein content was higher (0.01 > P < 0.05) during the first four lactation's months and decreased until the month 8. The β-LG was the major protein (1.75 mg mL(-1) as mean; peak 2.24 ± 0.09 mg mL(-1)), while the α-LA had a mean concentration of 1.32 mg mL(-1) and peaked at month 1 (1.57 ± 0.09 mg mL(-1)) and LYS (0.66 mg mL(-1) as mean) showed the highest value equal to 0.76 ± 0.03 mg mL(-1). The highest (P < 0.01) concentration of all proteins was recorded at spring (α-LA: 1.69 mL(-1); β-LG: 2.07 mL(-1); LYS: 0.76 mL(-1)).