Quality and glycemic index improvement of steamed bread by incorporating two phenolic acids and its mechanistic insights.

BACKGROUND

There is a notable lack of research focusing on the impact of phenolic acids on the quality of steamed bread and the mechanisms underlying the reduction of the glycemic index (GI) through the inhibition of α-amylase. This study aims to investigate the effects of ferulic acid (FA) and chlorogenic acid (CGA) on the quality and GI of steamed bread. Moreover, molecular docking and spectroscopy were employed to elucidate the mechanisms responsible for GI reduction.

RESULTS

At a concentration of 0.04 g kg-1, FA reduced the hardening rate of steamed bread by 46.1%, while CGA achieved a reduction of 43.8%. Additionally, FA and CGA decreased hardness by 46.0% and 35.5%, chewiness by 51.2% and 38.5% and stickiness by 53.2% and 37.9%, respectively. As the concentration of phenolic acids increased, the GI of the steamed bread progressively decreased. The starch solubility and swelling power achieved their peak values at a phenolic acid concentration of 4 × 10-3 g kg-1. Specifically, FA enhanced solubility to 10.99% (an increase of 3.89%) and increased swelling to 7.69% (an enhancement of 2.5%), while CGA increased solubility from 2.47% to 5.47% and swelling from 3.33% to 4.54%. CGA demonstrated a more potent inhibition of α-amylase, with a binding constant (Ka) of 3.287 × 105 L mol-1, compared to FA, which exhibited a Ka of 3.589 × 103 L mol-1 at 298 K. This inhibitory effect was primarily mediated through hydrophobic interactions, van der Waals forces and hydrogen bonding.

CONCLUSIONS

The data obtained suggest that the incorporation of FA and CGA can not only improve the texture of steamed bread, but also effectively inhibit α-amylase activity, thereby providing insights into the mechanism by which phenolic acids reduce the GI. © 2025 Society of Chemical Industry.