**5. Conclusions**

The present study demonstrated that CTE could inhibit pancreatic α-amylase activity, leading to a reduction of maltose release from flour. The addition of CTE to flour alters in vitro starch digestibility, resulting in a reduction in the amount of glucose released from the various types of flour and a subsequent reduction of HI and pGI. Moreover, the addition of the CTE reduced the starch digestibility rate and pGI of wheat bread. The findings indicate that the addition of CTE into flour can inhibit the starch digestibility of flour through the inhibition of carbohydrate digestive enzymes, including pancreatic α-amylase and intestinal α-glucosidase. We sugges<sup>t</sup> that CTE may be a potent ingredient for the reduced glycemic index of flours.

**Author Contributions:** S.A. and C.J.H. were responsible for the study concept and design, supervising the study, and drafting and revising the content of the manuscript. C.C. conducted the study, data collection and analysis, and interpreted the data and drafted the manuscript. P.C. and V.T. were responsible for drafting the content of the manuscript. All of the authors read and approved the final manuscript.

**Acknowledgments:** We would like to thank the 100th Anniversary Chulalongkorn University Fund for the Doctoral Scholarship, Overseas Research Experience Scholarship for Graduate Student, and the 90th Anniversary Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund), Graduate school, Chulalongkorn University. This research was supported by the Grant for International Research Integration: Chula Research Scholar, and the Grant for Join Funding, Ratchadaphiseksomphot Endowment Fund, Chulalongkorn University. The author gratefully acknowledges Lalana Thiranusornkij and Parichart Thamnarathip from KCG Excellence Center, KCG Corporation Co., Ltd. for providing bread preparation.

**Conflicts of Interest:** The authors have declared no conflict of interest.
