Steam explosion has gained much attention in the food industry. This study aimed to investigate if steam explosion could change the composition of phenolic compounds and antioxidant feature of a Chinese indigenous herb “Hangbaiju” (HBJ). Results showed that the color attributes, microstructure, and composition of phenolic compounds of HBJ were altered after the pretreatment. With the increasing pressure and duration, the contents of 3‐ and 4‐O‐caffeoylquinic acid increased. Meanwhile, some flavone aglycones, such as apigenin, luteolin, and acacetin, showed content increases, whereas apigenin‐7‐O‐glucoside, luteolin‐7‐O‐glucoside, and diosmetin‐7‐O‐glucoside showed content increases and then decreases. Furthermore, 3,5‐O‐caffeoylquinic acid and 5‐O‐caffeoylquinic acid exhibited content reduction. Some caffeoylquinic acids exhibited the structural rearrangement and degradation during the steam explosion, which also hydrolyze flavone glycosides to flavone aglycones. Hence, steam explosion pretreatment is suitable for the extraction of 3‐O‐caffeoylquinic acid, 4‐O‐caffeoylquinic acid, and some flavone aglycones, as well as the modification of HBJ samples. Novelty impact statement Steam explosion altered the appearance of “Hangbaiju” and disrupted its microstructure. Different pressure and duration of steam explosion showed different effect on phenolic compounds composition and antioxidant capacities of “Hangbaiju.” Furthermore, steam explosion pretreatment increased flavone aglycones content in “Hangbaiju.”

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This study investigated the effect of different drying treatments on phenolic composition and antioxidant activity in different fractions of Sedum aizoon L. Results showed that the highest flavonoids content was found in the flower fraction, which also possessed the strongest antioxidant capacity confirmed by DPPH, ABTS, and FRAP assays. Four phenolic compounds were detected in Sedum aizoon L. Myricetrin and quercitrin were the dominant phenolic compounds in all the fractions, whereas the stem fraction did not contain myricetin. Among the drying treatments, each freeze‐dried fraction exhibited the highest antioxidant activities and total flavonoids. The oven‐ and sun‐drying treatments resulted in a loss on the total flavonoids and antioxidant properties. A positive correlation of antioxidant activities in Sedum aizoon L. was found with myricetrin, quercitrin and total flavonoids. This study could provide useful information on the nutritional quality improvement of Sedum aizoon L. through different drying methods. Practical applications Sedum aizoon L. has been generally consumed as a folk medicine with multiple health beneficial features in China. The health beneficial properties of Sedum aizoon L. have been confirmed to be attributed primarily to phytochemicals, such as flavonoids and phenolic acids. The major consumption parts in Sedum aizoon L. in China include stems, leaves, and flowers. Normally, a drying process has been applied to Sedum aizoon L. for a longer shelf life need. The present study investigated the distribution of gallic acid, myricetrin, quercitrin, and myricetin in different parts of Sedum aizoon L., and further assessed if different drying methods could alter the level of these phenolic compounds and antioxidant properties in these parts of Sedum aizoon L. This study provides direct knowledge on the accumulation of phenolic compounds in different parts of Sedum aizoon L., and further bring a practical method on the best preserve functional compounds in Sedum aizoon L.