Improving functional properties of rice protein isolates by hydrolysis using alcalase enzyme and assessing bioactivities of hydrolysates

Background

Developing value-added products from rice grains is becoming increasingly significant to enhance productivity from excess rice grains. Therefore, the objective of this study was to improve the functional properties of rice protein from four rice varieties, namely, RRF-127, RRF-105, Swarna, and Protezin by enzymatic hydrolysis, and also to evaluate bioactivities like antioxidant, ACE, and DPP-IV inhibitory activities of the hydrolysates.

Results

The alcalase hydrolysis increased protein solubility to >80% in the pH range of 4–10. The foaming capacity and stability of rice protein hydrolysates (RPHs) improved with the increase in pH. The hydrolysis significantly improved the emulsification activity index (EAI) in the pH range of 5–9. The hydrolysates showed antioxidant activity, namely, ABTS^•+radical scavenging, reducing power, and metal ion chelation. RRF-105 was found to possess the most potent antioxidant capacity among the hydrolysates. RPH could alleviate oxidative damage in erythrocytes, and their protective effects were concentration-dependent. The hydrolysates had stronger inhibition of ACE and DPP-IV enzymes. Protezin exhibited the highest ACE inhibition (63%), while Swarna demonstrated the most effective DPP-IV inhibition (66%).

Conclusion

Hydrolysis with alcalase improved the functional and bioactive properties of rice proteins, indicating that RPH could serve as a source of bioactive peptides or as a functional ingredient with potential properties.