l-Theanine improves emulsification stability and antioxidant capacity of diacylglycerol by hydrophobic binding β-lactoglobulin as emulsion surface stabilizer

•l-theanine conjugates β-lactoglobulin by hydrophobic interaction.•Diacylglycerol emulsion stabilized by l-theanine and β-lactoglobulin complex was prepared.•l-theanine and β-lactoglobulin complex was better to be used as stabilizers of diacylglycerol.•l-theanine improves emulsification and antioxidant capacity of diacylglycerol emulsion.