Maillard reaction impairs the prebiotic properties of 2′-fucosyllactose after conjugation with α-lactalbumin

2′-Fucosyllactose (2′-FL), a human milk oligosaccharide with prebiotic properties, has been incorporated into infant formula. α-Lactalbumin (α-LA), a key milk protein, may undergo the Maillard reaction with 2′-FL upon heating and extended storage. However, the impact of this reaction on the prebiotic activity of 2′-FL remains unclear. This study confirmed the formation of Maillard reaction products (MRPs) through the measurement of furosine and free 2′-FL levels. Mass spectrometry analysis identified that α-LA can conjugate with seven 2′-FL molecules, resulting in high-molecular-weight MRPs. In vitro assays revealed that α-LA-2′-FL complexes significantly reduced the growth and metabolism of Bifidobacterium , as evidenced by a 47 % decrease in Bifidobacterium density and a 62 % decrease in the production of short-chain fatty acids. These findings highlight for the first time the reduced prebiotic properties of 2′-FL upon interaction with α-LA, providing valuable insights for preserving the functional properties of infant formula during formulation and storage.