Antioxidative and Anti-α-glucosidase Activities of Enzymatically Hydrolyzed Tea Seed Protein

Objective Antioxidative and anti-α-glucosidase activities of enzymatically hydrolyzed protein extracted from tea seed meal were determined for the development of a functional peptide product.

Method Camellia sinensis seed meal was alkaline-extracted using 0.1 mol·L⁻¹ NaOH and followed by acid precipitation with 1 mol·L⁻¹ HCl at pH 3.5 to obtain crude protein which was subsequently enzymatically hydrolyzed. The hydrolysates produced by applying alcalase, a neutral protease, or papain were tested for DPPH and ABTS free radical scavenging capacities as well as reducing power and α-glucosidase inhibition.

Result The tea seed protein extraction process yielded 7.7% solids that contained 27.6% protein. Among the 3 proteases, alacase delivered a hydrolysate with the highest IC₅₀ of 80.17 μg·mL⁻¹ in scavenging DPPH free radicals and an IC₅₀ of 123.79 μg·mL⁻¹ in scavenging ABTS free radicals. The hydrolysate also showed the greatest total reducing power of 0.458 and α-glucosidase inhibition rate of 93.12% at an applied concentration of 1 mg·mL⁻¹.

Conclusion The alacase-hydrolyzed tea seed protein exhibited significant in vitro free radical scavenging and anti-α-glucosidase activities of a bioactive peptide.