The encapsulation of lycopene with α-lactalbumin nanotubes to enhance their anti-oxidant activity, viscosity and colloidal stability in dairy drink

Nano-encapsulation is promising in improving the stability and biological activity of bioactive compounds. Here, the food-sourced protein nanotubes (NTs) from self-assembly of partially hydrolyzed α-lactalbumin (α-lac) were developed. The α-lac NTs had a dimension of 20 nm in diameter and 200–1000 nm in length. Lycopene (LYC) was loaded into the hydrophobic inner wall of NTs via hydrophobic interaction. Interestingly, we discovered that NTs became nanospheres in gastrointestinal conditions and LYC was mainly released under intestinal condition. The stability of LYC loaded in NTs against temperature and UV light was greatly improved. Besides, LYC showed an improved antioxidant property after NTs loading both by DPPH method and Caco-2 cellular antioxidant activity method. Additionally, the colloidal stability of LYC was greatly enhanced by NTs and therefore lycopene-loaded α-lac nanotubes (NTs/LYC) can be successfully added in the dairy drink, showing an increased viscosity and a long-term stability. α-Lac NTs have shown a promising future in protecting and delivering the hydrophobic compounds in food system.