Effect of Zijuan tea (Camellia sinensis var. assamica cv. Zijuan) on starch digestion properties of bread and its mechanisms

Summary This study investigated the effect of water extract (ZTWE) and ethanol extract (ZTEE) from Zijuan tea on the in vitro starch digestibility of bread, as well as the underlying mechanisms. Results revealed that the ZTWE and ZTEE could reduce the starch digestibility of bread, especially ZTEE, which may be due to the higher polyphenols contains in ZTEE (TPC: 233.11 mg GAE/g) than ZTWE (TPC: 195.94 mg GAE/g). Furthermore, results of enzyme activity experiments and in silico analyses demonstrated that the main four polyphenols enriched in ZTWE and ZTEE could inhibit the activities of starch digestive enzymes. Additionally, scanning electron microscopy and in silico analyses showed that the predominant polyphenols in ZTWE and ZTEE could interact with the starch molecule to alter its structure, thereby reducing the starch digestibility. These findings may offer a theoretical foundation for the development of Zijuan tea‐based functional products aimed at diabetes management.