Antioxidative and α-Glucosidase Inhibition Activities of Protein Hydrolysates of White Tea

Objective The enzymatically hydrolyzed protein from white tea was analyzed for antioxidant and α-glucosidase inhibition for the development of a functional ingredient.

Method Protein extracted by alkali solution from Shoumei white tea was acid-precipitated prior to protease hydrolysis using alcalase, papain, neutrase, or protamex. Rates of DPPH and ABTS free radical scavenging as well as total reducing power and α-glucosidase inhibition of the resulting hydrolysates were determined.

Result The extraction applied 0.3 mol·L⁻¹ NaOH to solubilize protein from the white tea and precipitated at pH 3.0 to yield 7.1% of a material containing 46.6% protein for the subsequent enzymatic hydrolysis. The hydrolysate of the 200 μg·mL⁻¹ papain digestion exhibited the highest DPPH radical scavenging rate at 86.8%; The four protease hydrolysates were comparable in their ability to scavenge ABTS free radicals; and that of 1000 μg·mL⁻¹ protamex, the total reducing power was the highest, amounting to 0.930; and that of the 1000 μg·mL⁻¹ neutrase, the most powerful α-glucoglycanase inhibition at 97.8%.

Conclusion It appeared that the application of neturase, protamex, or papain to enzymatically hydrolyze the white tea protein extract could produce peptides with significant antioxidative and α-glucosidase inhibition activities rendering a potential bioactive agent as a functional ingredient.